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1
SX8634
Low Power, Capacitive Button and Slider Touch Controller
(12 sensors) with Enhanced LED Drivers and Proximity Sensing
GENERAL DESCRIPTION
The SX8634 is an ultra low power, fully integrated
12-channel solution for capacitive touch-buttons and
slider applications and proximity detection. Unlike
many capacitive touch solutions, the SX8634
features dedicated capacitive sense inputs (that
requires no external components) in addition to 8
general purpose I/O ports (GPIO). Each GPIO is
typically configured as LED driver with independent
PWM source for enhanced lighting control such as
intensity and fading.
The SX8634 inc lu des a capacitive 10 bit ADC an alog
interface with automatic compensation up to 100pF.
The high resolution capacitive sensing supports a
wide variety of touch pad sizes and shapes and
allows capacitive buttons to be created using thick
overlay materials (up to 5mm) for an extremely
robust and ESD immune system design.
The SX8634 incorporates a versatile firmware that
was specially designed to simplify capacitive touch
solution design and offers reduced time-to-market.
Integrated multi-time programmable memory
provides the ultimate flexibility to modify key firmware
parameters (gain, threshold, scan period, auto offset
compensation… ) in the field without the need for
new firmware development.
The SX8634 supports the 400 kHz I²C serial bus
data protocol and includes a field programmable
slave addr ess. The tin y 5m m x 5mm footpr int makes
it an ideal solution for portable, battery powered
applications where power and density are at a
premium.
TYPICAL APPLIC ATION CIRCUIT
proximity
SX8634
cap2
cap3
cap4
cap5
cap6
cap8
cap7
cap9
gnd
gpio5
gpio4
gpio3
gpio2
gpio1
gnd
gpio0
cap1
cap0
vana
resetb
gnd
gpio7
vdig
gpio6
cap10
cap11
cn
cp
vdd
scl
intb
sda
analog
sensor
interface
micro
processor
RAM
ROM
NVM
I2C
GPIO
controller
power management
clock
generation
RC
PWM
LED
controller
bottom plate
HOST
d1
d0
d2
d3
d4
d5
d6
d7
d0
d1
d2
d3
d4
d5
d6
d7
KEY PRODUCT FEATURES
Complete Twelve Sensors Capacitive Touch Controller for
Buttons and Slider
Pre-configured for 6 Button s and a Slider
8 LED Drivers with Individual Intensity, Fading Control
and Autolight Mode
256 steps PWM Linear and Logarit hm ic contr ol
Proximity Sensing up to several centimetres
High Resolution Capacitive Sensing
Up to 100pF of Offset Capacitance Compensation at
Full Sensitivity
Capable of Sensing through Overlay Materials up to
5mm thick
Extremely Low Power Optimized for Portable Application
8uA (typ) in Sleep Mode
80uA (typ) in Doze Mode (Scanning Period 195ms)
220uA (typ) in Active Mode (Scanning Period 30ms)
Programmable Scanning Period from 15ms to 1500ms
Auto Offset Compensation
Eliminates False Triggers due to Environmental
Factors (Temperature, Humidity)
Initiated on Pow er-up and Configurable Intervals
Multi-Time In-Field Programmable Firmware Parameters
for Ultimate Flexibility
On-chip user programmab le mem ory for fast, sel f
contained start-up
"Smart" Wake-up Sequence for Easy Activation from Doze
No External Components per Sensor Input
Internal Clock Requires No External Components
Differential Sensor Sampling for Reduced EMI
400 KHz Fast-Mode I²C Interface with Interrupt
-40°C to +85°C Operation
APPLICATIONS
Notebook/Netbook/Port abl e/H andhe ld co mput ers
Cell phones, PDAs
Consumer Products, Instrumentation, Automotive
Mechanical Button Replacement
ORDERING INFORMATION
Part Number
Temperature
Range
Package
SX8634I05AWLTRT1
-40°C to +85°C
Lead Free MLPQ-W32
1 3000 Units/reel
* This device is RoHS/WEEE compliant and Halogen Free
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SX8634
Low Power, Capacitive Button and Slider Touch Controller
(12 sensors) with Enhanced LED Drivers and Proximity Sensing
Table of Contents
GENERAL DESCRIPTION ........................................................................................................................ 1
TYPICAL APPLIC ATION CIRCUIT ............................................................................................................ 1
KEY PRODUCT FEATURES..................................................................................................................... 1
APPLICATIONS ....................................................................................................................................... 1
ORDERING INFORMATION...................................................................................................................... 1
1 GENERAL DESCRIPTION ............................................................................................................... 4
1.1 Pin Diagram 4
1.2 Marking information 4
1.3 Pin Description 5
1.4 Simplified Block Diagram 6
1.5 Acronyms 6
2 ELECTRICAL CHARACTERISTICS ................................................................................................. 7
2.1 Absolute Maximum Ratings 7
2.2 Recommended Operating Conditions 7
2.3 Thermal Characteristics 7
2.4 Electrical Specifications 8
3 FUNCTIONAL DESCRIPTION ........................................................................................................ 10
3.1 Qu ickstart Applicatio n 10
3.2 Introduction 10
3.2.1 General 10
3.2.2 GPIOs 11
3.2.3 Parameters 11
3.2.4 Configuration 11
3.3 Scan Period 12
3.4 Operation modes 12
3.5 Sensors on the PCB 14
3.6 Button and Slider I n fo rmation 15
3.6.1 Button Information 15
3.6.2 Slider Information 15
3.7 Analog Sensing In terface 17
3.8 Offset Compensation 18
3.9 Processing 19
3.10 Configuration 19
3.11 Power Management 21
3.12 Clock Circuitry 21
3.13 I2C interface 21
3.14 Reset 22
3.14.1 Power up 22
3.14.2 RESETB 22
3.14.3 Software Reset 23
3.15 Interrupt 24
3.15.1 Power up 24
3.15.2 Assertion 24
3.15.3 Clearing 24
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SX8634
Low Power, Capacitive Button and Slider Touch Controller
(12 sensors) with Enhanced LED Drivers and Proximity Sensing
3.15.4 Example 25
3.16 General Purpose Input and Outputs 25
3.16.1 Introduction and Definitions 25
3.16.2 GPI 26
3.16.3 GPP 26
3.16.4 GPO 27
3.16.5 Intensity index vs PWM pulse width 30
3.17 Smart Wake Up 31
4 PIN DESCRIPTIONS ..................................................................................................................... 32
4.1 Introduction 32
4.2 ASI pins 32
4.3 Host interface pins 33
4.4 Power management pins 36
4.5 General purpose IO pins 37
5 DETAILED CONFIGURATION DESCRIPTIONS .............................................................................. 38
5.1 Introduction 38
5.2 General Parameters 41
5.3 Capacit iv e Sensors Param eters 42
5.4 Button Paramete rs 47
5.5 Slider Parameters 51
5.6 Mapping Parameters 55
5.7 GPIO Parameters 58
6 I2C INTERFACE ........................................................................................................................... 62
6.1 I2C Write 62
6.2 I2C read 63
6.3 I2C Registers Overview 64
6.4 Status Registers 65
6.5 Control Registers 68
6.6 SPM Gateway Registers 70
6.6.1 SPM Write Sequence 71
6.6.2 SPM Read Sequence 72
6.7 NVM burn 73
6.8 Monitor Mode 74
7 APPLICATION INFORMATION ...................................................................................................... 75
7.1 Typical Application Schematic 75
7.2 Example of Touch+Proximity Module 76
7.2.1 Overview 76
7.2.2 Operation 76
7.2.3 Performance 76
7.2.4 Schematics 77
7.2.5 Layout 78
8 REFERENCES ............................................................................................................................. 79
9 PACKAGING INFORMATION ........................................................................................................ 80
9.1 Package Outline Drawing 80
9.2 Land Pattern 80
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SX8634
Low Power, Capacitive Button and Slider Touch Controller
(12 sensors) with Enhanced LED Drivers and Proximity Sensing
1 GENERAL DESCRIPTION
1.1 Pin Diagram
SX8634
Top View
1
2
3
4
5
6
7
8
24
23
22
21
20
19
18
17
9 10 11 12 13 14 15 16
25262728293031
32
bottom ground pad
cap2
cap3
cap4
cap5
cap6
cap8
cap7
cap9
gnd
gpio5
gpio4
gpio3
gpio2
gpio1
gnd
gpio0
cap1
cap0
vana
resetb
gnd
gpio7
vdig
gpio6
cap10
cap11
cn
cp
vdd
scl
intb
sda
Figure 1 Pinout Diagram
1.2 Marking information
FJ24
yyww
xxxxxx
R05
yyww = Date Code
xxxxxx = Semtech lot number
R05 = Semtech Code
Figure 2 Marking I nf ormation
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SX8634
Low Power, Capacitive Button and Slider Touch Controller
(12 sensors) with Enhanced LED Drivers and Proximity Sensing
1.3 Pin Description
Number Name Type Description
1
CAP2
Analog
Capacitive Sensor 2
2
CAP3
Analog
Capacitive Sensor 3
3
CAP4
Analog
Capacitive Sensor 4
4
CAP5
Analog
Capacitive Sensor 5
5
CAP6
Analog
Capacitive Sensor 6
6
CAP7
Analog
Capacitive Sensor 7
7
CAP8
Analog
Capacitive Sensor 8
8
CAP9
Analog
Capacitive Sensor 9
9
CAP10
Analog
Capacitive Sensor 10
10
CAP11
Analog
Capacitive Sensor 11
11
CN
Analog
Integration Capacitor, negative terminal (1nF between CN and CP)
12
CP
Analog
Integration Capacitor, positive terminal (1nF between CN and CP)
13
VDD
Power
Main input power supply
14
INTB
Digital Output
Interrupt, active LOW, requires pull up resistor (on host or external)
15
SCL
Digital Input
I2C Clock, requires pull up resistor (on host or external)
16
SDA
Digital Input/Output
I2C Data, requires pull up resistor (on host or external)
17
GPIO0
Digital Input/Output
General Purpose Input/Output 0
18
GPIO1
Digital Input/Output
General Purpose Input/Output 1
19
GND
Ground
Ground
20
GPIO2
Digital Input/Output
General Purpose Input/Output 2
21
GPIO3
Digital Input/Output
General Purpose Input/Output 3
22
GPIO4
Digital Input/Output
General Purpose Input/Output 4
23
GPIO5
Digital Input/Output
General Purpose Input/Output 5
24
GND
Ground
Ground
25
GPIO6
Digital Input/Output
General Purpose Input/Output 6
26
GPIO7
Digital Input/Output
General Purpose Input/Output 7
27
VDIG
Analog
Digital Core Decoupling, connect to a 100nF decoupling capacitor
28
GND
Ground
Ground
29
RESETB
Digital Input
Active Low Reset. Connect to VDD if not used.
30
VANA
Analog
Analog Core Decoupling, connect to a 100nF decoupling capacitor
31
CAP0
Analog
Capacitive Sensor 0
32
CAP1
Analog
Capacitive Sensor 1
bottom plate
GND
Ground
Exposed pad con nec t to grou n d
Table 1 Pin descr ipt ion
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SX8634
Low Power, Capacitive Button and Slider Touch Controller
(12 sensors) with Enhanced LED Drivers and Proximity Sensing
1.4 Simplified Block Diagram
The simplified block diagram of the SX8634 is illustrated in Figure 3.
SX8634
cap2
cap3
cap4
cap5
cap6
cap8
cap7
cap9
gnd
gpio5
gpio4
gpio3
gpio2
gpio1
gnd
gpio0
cap1
cap0
vana
resetb
gnd
gpio7
vdig
gpio6
cap10
cap11
cn
cp
vdd
scl
intb
sda
analog
sensor
interface
micro
processor
RAM
ROM I2C
GPIO
controller
power management
clock
generation
RC
PWM
LED
controller
bottom plate
NVM
Figure 3 Simplified block diagram of the SX8634
1.5 Acronyms
ASI Analog Sensor Interface
DCV Digital Compensation Value
GPI General Purpose Input
GPO General Purpose Output
GPP General Purpose PWM
MTP Multiple Time Programmable
NVM Non Volatile Memory
PWM Pulse Width Modulation
QSM Quick Start Memory
SPM Shadow Parameter Memory
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SX8634
Low Power, Capacitive Button and Slider Touch Controller
(12 sensors) with Enhanced LED Drivers and Proximity Sensing
2 ELECTRICAL CHARACTERISTICS
2.1 Abs ol ute Maximum Ratings
Stresses above the values listed in “Absolute Maximum Ratings” may cause permanent damage to the device.
This is a stress rating only and functional operation of the device at these, or any other conditions beyond the “Recommended
Operating Conditions”, is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device
reliability.
Parameter Symbol Min. Max. Unit
Supply Voltage
VDD
-0.5
3.9
V
Input voltage (non-supply pins)
V
IN
-0.5
3.9
V
Input current (n on-supply pins)
I
IN
10
mA
Operating Junction Temperature
T
JCT
125
°C
Reflow temperature
T
RE
260
°C
Storage temperature
T
STOR
-50
150
°C
ESD HBM (Human Body model)(i)
ESD
HBM
3
kV
Latchup(ii)
I
LU
± 100
mA
Table 2 Absolute Maximum Ratings
(i) Tested to JEDEC standar d JESD 22-A114
(ii) Tested to JEDEC standar d JES D78
2.2 Recommended Operating Conditions
Parameter Symbol Min. Max. Unit
Supply Voltage
VDD
2.7V
3.6
V
Supply Voltage Drop(iii, iv, v)
VDD
drop
100
mV
Supply Voltage for NVM programming
VDD
3.6
3.7
V
Ambient Temperature Range
T
A
-40
85
°C
Table 3 Recommended Oper at ing Conditions
(iii) Performance for 2.6V < VDD < 2.7V might be degraded.
(iv) Operation is not guaranteed below 2.6V. Should VDD briefly drop below this minimum value, then the SX8634 may
require;
- a hardware reset issued by the host using the RESETB pin
- a software reset issued by the host using the I2C interface
(v) In the event the host processor is reset or undergoes a power OFF/ON c ycle , it is rec ommend ed that t he host also resets
the SX8634 and assures that parameters are re-written into the SPM (should these differ to the parameters held in NVM).
2.3 Thermal Characteristics
Parameter Symbol Min. Max. Unit
Thermal Resistance - Junction to Ambient (vi)
θ
JA
25
°C/W
Table 4 Thermal Charac terist ics
(vi) Static airflow
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SX8634
Low Power, Capacitive Button and Slider Touch Controller
(12 sensors) with Enhanced LED Drivers and Proximity Sensing
2.4 Electrical Specif icat ions
All values are valid within the operating conditions unless otherwise specified.
Parameter
Symbol
Conditions
Min.
Typ.
Max.
Unit
Current consumption
Active mode, average
I
OP,active
30ms scan period,
12 sensors enabled,
minimum sensitivity
220
300
uA
Doze mode, average
I
OP,Doze
195ms scan period,
12 sensors enabled,
minimum sensitivity
80
110
uA
Sleep
I
OP,sleep
I2C and GPI listening,
sensors disabled
8
17
uA
GPIO, set as Input, RESETB, SCL, SDA
Input logic high
V
IH
0.7*VDD
VDD + 0.3V
V
Input logic low
V
IL
VSS applied to GND pins
VSS - 0.3V
0.8
V
Input leakage cur rent
L
I
CMOS input
±1
uA
Pull up resistor
R
PU
when enabled
660
kΩ
Pull down resistor
R
PD
when enabled
660
kΩ
GPIO set as Output, INTB, SDA
Output logic high
V
OH
I
OH
<4mA
VDD-0.4
V
Output logic low
V
OL
I
OL,GPIO
<12mA
IOL,SDA,INTB<4mA
0.4
V
Start-up
Power up time
t
por
time between risi ng edge
VDD and rising INTB
150
ms
RESETB
Pulse width
t
res
50
ns
Recommended External components
Capacitor between VDIG, GND
C
vdig
type 0402, tolerance +/-50%
100
nF
Capacitor between VANA, GND
C
vana
type 0402, tolerance +/-50%
100
nF
Capacitor between CP, CN
C
int
type 0402, COG, tolerance +/-5%
1
nF
Capacitor between VDD, GND
C
vdd
type 0402, tolerance +/-50%
270
nF
Table 5 Electrical Specifications
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SX8634
Low Power, Capacitive Button and Slider Touch Controller
(12 sensors) with Enhanced LED Drivers and Proximity Sensing
Parameter Symbol Conditions Min. Typ. Max. Unit
I2C Timing Specifications (i)
SCL clock frequency
fSCL
400
KHz
SCL low period
tLOW
1.3
us
SCL high period
tHIGH
0.6
us
Data setup time
tSU;DAT
100
ns
Data hold time
tHD;DAT
0
ns
Repeated start setup time
tSU;STA
0.6
us
Start condition hold time
tHD;STA
0.6
us
Stop condition setup time
tSU;STO
0.6
us
Bus free time between stop and start
tBUF
500
us
Input glitch suppr e ssion
tSP
50
ns
Table 6 I2C Timing Specificat ion
Notes:
(i) All timing specifications, Figure 4 and Figure 5, refer to voltage levels (VIL, VIH, VOL) defined in Table 5.
The interface complies with slave F/S mode as described by NXP: “I2C-bus specification, Rev. 03 - 19 June 2007”
SDA
SCL
tSU;STA tHD;STA tSU;STO tBUF
70%
30%
70%
Figure 4 I2C St ar t and Stop timing
SDA
SCL
t
LOW
t
HIGH
t
HD;DAT
t
SU;DAT
t
SP
70%
30%
70%
30%
Figure 5 I 2C Data t iming
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SX8634
Low Power, Capacitive Button and Slider Touch Controller
(12 sensors) with Enhanced LED Drivers and Proximity Sensing
3 FUNCTIONAL DESCRIPTION
3.1 Quickstart Application
The SX8634 is preconfigured (Quickstart Application) for an application with 6 buttons, a slider (consisting of 6
sensors) and 8 LED drivers using logarithmic PWM fading.
Implem enting a sc hem atic based on Figure 6 will be im mediatel y operational af ter powering with out pr ogr am ming
the SX8634 (even without host).
cap2
cap3
cap4
cap5
gnd
gpio5
gpio4
gpio3
gpio2
gpio1
gnd
gpio0
cap1
cap0
vana
resetb
gnd
gpio7
vdig
gpio6
cn
cp
vdd
scl
intb
sda
analog
sensor
interface
micro
processor
RAM
ROM
NVM
I2C
GPIO
controller
power management
clock
generation
RC
PWM
LED
controller
bottom plate
d1
d0
d2
d3
d4
d5
d6
d7
d0
d1
d2
d3
d4
d5
SX8634
HOST
cap6
cap8
cap7
cap9
cap10
cap11
d6
d7
Figure 6 Quickstart Application
Touching the sensor on the CAP0 pin will enable automatically the LED connected to GPIO0. When the CAP0
sensor is released the LED on GPIO0 will slowly fade-out using smooth logarithmic fading.
All other sensors (CAP1 to CAP5) have their own LED associated on a GPIO pin showing a touch or a release.
The sensors on CAP6 to CAP11 are used in a slider configuration. A moving finger on the slider will enable the
LED on GPIO6 or GPIO7 indicating the finger movement.
The sensor detection and the LED fading described above are operational without any host interaction.
This is made possible using the SX8634 Autolight feature described in the following sections.
3.2 Introduction
3.2.1 General
The SX8634 is intended to be used in applications which require capacitive sensors covered by isolating overlay
material and which need to detect the proximity of a finger/hand though the air. A finger approaching the
capacitive sensors will ch ange the charge th at can b e loade d on the s ensors . The SX8634 m easures the change
of char ge and conver ts that into dig ita l val ues (tick s) . The larger the char ge on t he sens ors, the lar ger the n umber
of ticks will be. The charge to ticks conversion is done by the SX8634 Analog Sensor Interface (ASI).
The ticks are further processed by the SX8634 and converted in a high level, easy to use information for the
user’s host.
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SX8634
Low Power, Capacitive Button and Slider Touch Controller
(12 sensors) with Enhanced LED Drivers and Proximity Sensing
The information between SX8634 and the user’s host is passed through the I2C interface with an additional
interrupt signal indicating that the SX8634 has new information. For buttons this information is simply touched or
released.
3.2.2 GPIOs
A second path of feedback to the user is using General Purpose Input Output (GPIO) pins. The SX8634 offers
eight individual configurable GPIO pins. The GPIO can e.g. be set as a LED driver which slowly fade-in when a
finger touches a button and slowly fade-out when the button is released. Fading intensity variations can be
logarithmic or linear. Interval speed and initial and final light intensity can be selected by the user. The fading is
done using a 256 steps PWM. The SX8634 has eight individual PWM generators, one for each GPIO pin.
The LED fading can be initiated automatically by the SX8634 by setting the SX8634 Autolight feature. A simple
touch on a sensor and the corr es ponding LED will fade-in without any host intera c tion ov er the I2C.
In case the Autolight feature is disabl ed the n th e host will dec ide t o start a LE D f ading-in p erio d, sim ply b y setti ng
the GP0 pin to ‘high’ using one I2C command. The SX8634 will then slowly fade-in the LED using the PWM
autonomously.
In case th e hos t needs t o h ave full c ontrol of the L ED i ntensi ty the n the hos t can set the G PIO i n GPP mode. T he
host is then able to set the PWM pulse width freely at the expense of an increased I2C occupation.
The GPIOs can be set further in the digital standard Input mode (GPI).
3.2.3 Parameters
The SX8634 has many low level built-in, fixed algorithms and procedures. To allow a lot of freedom for the user
and adapt the SX8634 for different applications these algorithms and procedures can be configured with a large
set of parameters which will be described in the following sections. Examples of parameters are which sensors
are buttons or which sensors are parts of a slider, which GPIO is used for outputs or LEDs and which GPIO is
mapped to which button.
Sensitivity and detection thresholds of the sensors are part of these parameters. Assuming that overlay material
and sensors areas are identical then the sensitivities and thresholds will be the same for each sensor. In case
sensors are not of the same size then sensitivities or thresholds might be chosen individually per sensor.
So a smaller size sensor can have a larger sensitivity while a big size sensor may have the lower sensitivity.
3.2.4 Configuration
During a development phase the parameters can be determined and fine tuned by the users and downloaded
over the I2C in a dynamic way. The parameter set can be downloaded over the I2C by the host each time the
SX8634 boots up. This allows a flexible way of setting the parameters at the expense of I2C occupation.
In case the parameters are frozen they can be programmed in Multiple Time Programmable (MTP) Non Volatile
Memory (NVM) on the SX8634. The programming needs to be done once (over the I2C). The SX8634 will then
boot up from the NVM and add iti ona l parameters from the host are not required anymore.
In case the host desires to overwrite the boot-up NVM parameters (partly or even com plete) this can be done by
additional I2C communications.
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SX8634
Low Power, Capacitive Button and Slider Touch Controller
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3.3 Scan Period
The basic operation Scan period of the SX8634 sensing interface can be split into three periods over time.
In the first period (Sensing) the SX8634 is sensing all enabled CAP inputs , from CAP0 towards CAP11.
In the sec o nd per iod (Processing) the SX8634 proces s es the sensor d ata, verif ie s and up dat es th e G PI O a n d I2C
status registers.
In the third period (Timer) the SX8634 is set in a low power mode and waits until a new cycle starts.
Figure 7 shows the different SX8634 periods over time.
CAP0
CAP1
CAP11
sensing
data
processing
processing timer
CAP0
CAP1
scan period
time
timer
Figure 7 Scan Period
The sc an period det erm ines the m inim um r eaction time of th e SX8634. T he scan peri od can be co nfigure d b y the
host from 15ms to values larger than a second.
The reaction time is defined as the interval between a touch on the sensor and the moment that the SX8634
generates the interrupt on the INTB pin. The shorter the scan period the faster the reaction time will be.
Very low power consum ption c an be obtained by settin g very long s can p er io ds with the ex pens e of ha ving lo nger
reaction times.
Important: All external e ve nts like GPIO, I 2C a nd INTB are updated in th e pr oc e s sing period, so o nc e e very scan
period. If e.g. a GPI would change sta te directl y after t he processin g period then t his will be r eported with a delay
of one scan period later in time.
3.4 Operation modes
The SX8634 has 3 oper atio n m odes. T he main dif fer ence is found in the re actio n tim e ( corres ponding to the s can
period) and power consumption.
Active mode offers fast scan periods. The typical reaction time is 30ms. All enabled sensors are scanned and
information data is processed within this interval.
Doze mode increases the scan period time which increases the reaction time to 195ms typical and at the same
time reduces the opera tin g cur rent .
Sleep mode turns the SX8634 OFF, except for the I2C and GPI peripheral, minimizing operating current while
maintain ing the po wer supplies . In Sleep mode the SX8634 does not do any sensor scanning.
The user can specify other scan periods for the Active and Doze mode and decide for other compromises
between reaction time and power consumption.
In mos t applications the re action tim e needs to be fas t when fing ers ar e present, but can be s low when no per son
uses the application. In case the SX8634 is not used for a specific time it can go from Active mode into Doze
mode and p ower wi ll be saved . Th is tim e-out is deter mined b y the Pass ive Tim er which c an be c onfigured by the
user or turned OFF if not required.
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To leave Doze mode and enter Active mode this can be done by a simple touch on any button.
For some applications a single button touch might cause undesired wakening up and Active mode would be
entered too often.
The SX8634 offers therefore a smart wake-up sequence feature in which the user needs to touch and release a
correct sequence of button s before Active mode will be ent ered. This is explained in more detail in the Wake-Up
Sequence section.
The host can decide to force the operating mode by issuing commands over the I2C (using register
CompOpMode) and take fully control of the SX8634.
The diagram in Figure 8 shows the available operation modes and the possible transitions.
ACTIVE mode
DOZE mode
SLEEP mode
wake-up
sequence
detected
OR
GPI interrupt
OR
I2C cmd
GPI interrupt
OR
I2C cmd
I2C cmd
I2C cmd I2C cmd
Power On
I2C cmd
passive
timeout
'I2C cmd' - write to CompOpMode[1:0]
Figure 8 Operation modes
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3.5 Sensors on the PCB
The capac itive sens ors ar e relative ly sim ple copper ar eas on the PCB connec ted to the t welve SX8634 capacitive
sensor input pins (CAP0…CAP11).The sensors are covered by isolating overlay material (typically 1mm...3mm).
The area of a sensor is t ypically one s quare centim eter which corr esponds abo ut to the area of a finger t ouching
the overlay material.
The capacitive sensors can be setup as ON/OFF buttons for either touch or proximity sensing (see example
Figure 9) or arranged in a slider configuration (see example Figure 10) for e.g. menu scrolling or volume control
applications.
Figure 9 P CB t op layer of three touch buttons sensors surrounded by a proximity sensor
Figure 10 P CB t op layer of one slider using six sensors (surrounded by ground plane)
Please refer to the layout guidelines application note [1], for more details.
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3.6 Button and Slider Information
3.6.1 Button Information
The touch buttons have two simple states (see Figure 11): ON (touched by finger) and OFF (released and no
finger press).
off on off off
Figure 11 Buttons
A finger is detected as soon as the number of ticks from the ASI reaches a user-defined threshold plus a
hysteresis.
A release is detected if t he ticks from the ASI go below the threshold m inus a hysteresis. The h ysteresis around
the threshold avoids rapid touch and release signaling during transients.
Buttons c an also b e us ed t o do pr ox imity sensing. The princip le of prox imity sensing opera ti on is ex ac tly the same
as for touch buttons except that pr oximit y sensi ng is done several cent imeters ab ove the ov erlay through the air.
ON state means that finger/hand is detected by the sensor and OFF state means the finger/hand is far from the
sensor.
3.6.2 Slider Information
In case sens ors ar e arr anged i n a slider configurat ion the ON, OF F inf orm ation rem ains available as if it would be
a single sensor button.
ON OFF
Figure 12 Slider ON, OFF
Wherever the slider is touched the information will be set to ON. If no finger is present the slider information will be
OFF.
Due to the 2 dimensional character of the slider more information can be derived b y processing the ticks.
During a touch a finger will influence most of the time the charge on one or two sensors but never all of the
sensors at the same time. Some sensor ticks will be larger than others based on the finger position.
The processing algorithms can therefore determine where the finger is positioned on the slider.
Interpolation between sensors increases the resolution beyond the number of sensors in the slider.
The interpo lation can b e done a lready on the PCB s ensor st ructures (analog, lik e the chevron slider in Figure 10)
and as well by SX8634 digital processing of the ticks using center of gravity calculations.
The position of the finger on the PCB structures varies between the m inimum zero and a user defined m aximum
(Figure 13).
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....x...
position
min max
Figure 13 Slider Position
The positi on belonging to the minim um and ass ociated to a sensor is defined arbitrarily. The SX8634 defines the
minimum position to the se nsor with the lowes t CAP pin index . E.g. if CA P0 is a butto n (or d isabled) and C AP1 to
CAP7 are the sensors of the slider then the position ‘zero’ starts at CAP1 and the maximum is found at CAP7.
In addition to the slider position, the SX8634 allows to detect finger movements. The movement occurs if the
finger pos ition changes a certain step size between t wo succeeding scan periods. A very slow m oving finger will
not be considered as a movement as the changing position will be minor. The SX8634 allows detecting a move
low (direction max to min) (see Figure 14) and a move high (direction min to max) (see Figure 15).
min max
Figure 14 Slider Move Low
min max
Figure 15 Slider Move High
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3.7 Ana l og Sensing Interface
The Analog Sensing Interface (ASI) converts the charge on the sensors into ticks which will be further digitally
processed. The basic princ iple of the ASI will be expla i ned in this sec ti on.
The ASI cons ists of a m ultiplexer select ing the sensor , analog sw itches, a refer ence voltage, a n ADC sigma delt a
converter, an offset compensation DAC and an external integration capacitor (see Figure 16).
switches
cap2
cap9
cap10
cap11
cap1
cap0
cn
cp
analog
multi-
plexor
Offset
compensation
DAC
ADC
ticks (raw)
compensation DCV
ASI processing
Cint
voltage
reference
low pass
ticks-diff
ticks-ave
Figure 16 Analog Sensor Interface
To get the ticks representing the charge on a specific sensor the ASI will execute several steps.
The charge on a sensor ca p (e.g. CAP 0) will b e accu mulated m ultiple tim es on t he externa l integrati on cap acitor,
Cint.
This results in an increasing voltage on Cint proportional to the capacitance on CAP0.
At this stage the offset compensation DAC is enabled. The compensation DAC generates a voltage proportional
to an estimation of the external capacitance. The estimation is obtained by the offset compensation procedure
executed e.g. at power-up.
The difference between the DAC output and the charge on Cint is the desired signal. In the ideal case the
differ ence of charge will be convert ed to zero tic ks if no finger is pres ent and the num ber of ticks becom es high in
case a finger is present.
The difference of charge on Cint and the DAC output will be transferred to the ADC (Sigma Delta Integrator).
After the charge transfer to the ADC the steps above will be repeated.
The larger the number the cycles are repeated the larger the signal out of the ADC with improved SNR. The
sensitivity is therefore directly related to the number of cycles.
The SX8643 allows setting the sensitivity for each sensor individually in applications which have a variety of
sensors sizes or dif fer ent overla ys or for f ine-tuning pe rf ormanc es. The optim al s ensitivity is depe nding he avil y on
the final app lication. If the sensit ivity is too lo w the ticks will n ot pass the thres holds and touc h/proxim ity detection
will not be possible. In case the sensitivity is set too large, some power will be wasted and false touch/proximity
information may be output (ie for touch buttons => finger not touching yet, for proximity sensors => finger/hand not
close enough).
Once the ASI has finished the first sensor, the ticks are stored and the ASI will start measuring the next sensor
until all (enabled) sensors pins have been treated.
In case some sensors are disabled then these result in lower power consumption simply because the ASI is active
for a shorter period and the following processing period will be shorter.
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The ticks from the ASI will then be handled by the digital processing.
3.8 Offset Compensation
The capacitance at the CAP pins is determined by an intrinsic capacitance of the integrated circuit, the PCB
traces, gr ound c ou pl ing and the sensor pl anes . This capacit anc e is r el ati vely large and m ight bec ome easil y some
tens of pF. This parasitic capacitance will vary only slowly over time due to environmental changes.
A finger touch is in the order of one pF. If the finger approaches the sensor this occurs typically fast.
The ASI has the difficult task to detect and distinguish a small, fast changing capacitance, from a large, slow
varying c apacitance. T his would re quire a ver y pr ecise, high r esolution AD C and com plicated, power consum ing,
digital processing.
The SX8634 featur es a 16 bit DAC which c ompensat es for the large, s low var ying cap acitanc e alread y in fr ont of
the ADC. In other words the ADC converts only the desired small signal. In the ideal world the ADC will put out
zero ticks even if the external capacitance is as high as 100pF.
At each power-up of the SX8634 the Di gital Com pensation Values (DCV) are estim ated by the digital processing
algorithms. The algorithm will adjust the compensation values such that zero ticks will be generated by the ADC.
Once the correct compensation values are found these will be stored and used to compensate each CAP pin.
If the SX8634 is shut d own the com pensation values w ill be lost. At a next po wer -up the proced ure starts all over
again. T his assures th at the SX8634 will o perate under any condition . Powering up at e.g. diff erent temperatur es
will not change the performance of the SX8634 and the host does not have to do anything special.
The DCVs do not need to be updated if the external conditions remain stable.
However if e.g. temperature changes this will influence the external capacitance. The ADC ticks will drift then
slowly around zero values basically because of the mismatch of the compensation circuitry and the external
capacitance.
In case the average value of the ticks become higher than the positive noise threshold (configurable by user) or
lower than the negative threshold (configurable by user) then the SX8634 will initiate a compensation procedure
and find a new set of DCVs.
Compensation procedures can as well be initiated by the SX8634 on periodic intervals. Even if the ticks remain
within the positive and negative noise thresholds the compensation procedure will then estimate new sets of
DCVs.
Finall y the host can initiate a com pensation proc edur e by using the I2C inter face ( in Acti ve or D o ze mode). T h is is
e.g. required after the host changed the sensitivity of sensors.
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3.9 Processing
The firs t process ing step of the r aw tick s, c oming out o f the ASI, is low pas s f iltering to o btain an estim ation of t h e
average capacitance: tick-ave (see Figure 17).
This slowly vary ing average is important in the detection of slowly changing environmental changes.
ticks (raw)
compensation DCV
ASI processing
low pass
tick-diff
tick-ave
processing
GPIO
controller
PWM LED
controller
I2C
SPM
Figure 17 Processing
The difference of the tick average and the raw ticks, tick-diff, is a good estimation of rapid changing input
capacitances.
The tick-diff, tick-ave an d t he c onf ig urat ion par ameters in t he SP M are then proc es sed and determines the s ensor
information, I2C registers status and PWM control.
3.10 Configuration
Figure 18 shows the building blocks used for configuring the SX8634.
micro
processor
MTP
NVM
I2C
SX8634
HOST
SPM QSM
Figure 18 Configuration
The default configuration parameters of the SX8634 are stored in the Quick Start Memory (QSM). This
configurat ion data is setup to a very comm on application f or the SX8634 with 6 buttons and a slider. Without any
programming or host interaction the SX8634 will startup in the Quick Start Application.
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The QSM settings are fixed and can not be changed by the user.
In case the application needs different settings than the QSM settings then the SX8634 can be setup and/or
programmed over the I2C interface.
The configuration parameters of the SX8634 can be stored in the Multiple Time Programmable (MTP) Non
Volatile Memory (NVM). The NVM contains all those parameters that are defined and stable for the application.
Examples are the number of sensors enabled, sensitivity, active and Doze scan period. The details of these
parameters are described in the next chapters.
At power up the SX8634 checks if the NVM contains valid data. In that case the configuration parameter source
becom es the NV M. If the N VM is em pt y or non-va lid t hen t he co nfigurat ion s ource becom es t he QSM. In t he nex t
step the SX8634 copies the configuration param eter source (QSM or NVM) into the Shadow Parameter M emory
(SPM). The SX8634 is operational and uses the configuration parameters of the SPM.
During p o wer do wn or res e t e vent th e SP M l os es a ll c onte nt. I t w ill a utomatical ly be r e loa ded (f r om Q SM or NVM)
following power up or at the end of the reset event.
The host will interface with the SX8634 through the I2C bus.
The I2C of the SX8634 consists of 16 registers. Some of these I2C registers are used to read the status and
inform ation of the button an d the slider. Other I2 C regis ters allo w the host to t ak e control of the SX8634. T he host
can e.g. decide to change the operation mode from Active mode to Doze mode or go into Sleep (according to
Figure 8).
Two additional modes allow the host to have an access to the SPM or indirect access to the NVM.
These modes are required during development, can be used in real time or in-field programming.
Figure 19 shows the Host SPM mode. In this mode the host can decide to overwrite the SPM. This is useful
during the d evelo pment phases of the applic ati on whe re the c onf iguration parameters ar e not yet ful ly def ine d and
as well during the operation of the application if some parameters need to be changed d ynamicall y.
micro
processor
MTP
NVM
I2C
SX8634
HOST
SPM
Figure 19 Host SPM mode
The cont ent of the S PM re mains valid as long as the SX8634 is powered a nd no r eset is performed. Af ter a po wer
down or reset the host needs to re-write the SPM if relevant for the application.
Figure 20 shows the Host NVM mode. In this mode the host will be able to write the NVM.
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micro
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MTP
NVM
I2C
SX8634
HOST
SPM
1
2
Figure 20 Host NVM mode
The writing of the host towards the NV M is not done directly but done in 2 steps (Figure 20).
In the first step the host writes to the SPM (as in Figure 19). In the second step the host signals the SX8634 to
copy the SPM content into the NVM.
Initially the NVM memory is empty and it is required to determine a valid parameter set for the application. This
can be done during the development phase using dedicated evaluation hardware representing the final
application. This development phase uses probably initially the host SPM mode which allows faster iterations.
Once the p arameter set is determ ined this c an be written t o the NVM over the I2C us ing the 2 steps approa ch by
the host or a dedicated programmer for large volumes production (as described in the paragraphs 6.6 and 6.7).
3.11 Power Management
The SX8634 uses on-chip voltage regulators which are controlled by the on-chip microprocessor. The regulators
need to be stabilized with an external capacitor between VANA and ground and between VDIG and ground (see
Table 5). Both regulators are designed to only drive the SX8634 internal circuitry and must not be loaded
externally.
3.12 Clock Circuitry
The SX8634 has its own internal clock generation circuitry that does not require any external components. The
clock circuitry is optimized for low power operation and is controlled by the on-chip microprocessor. The typical
operating frequency of the oscillating core is 16.7MHz from which all other lower frequencies are derived.
3.13 I2C interface
The I2C interface allows the communication between the host and the SX8634.
The I2C slave implemented on the SX8634 is compliant with the standard (100kb/s) and fast mode (400kb/s)
The default SX8634 I2C address equals 0b010 1011.
A different I2C address can be programmed by the user in the NVM.
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3.14 Reset
The reset can be performed by 3 sources:
- power up,
- RESETB pin,
- software reset.
3.14.1 Power up
During power up the INTB is kept low. Once the power up sequence is terminated the INTB is released
autonomously. The SX8634 is then ready for operation.
VDD
INTB
time
VDD
t por
supply
voltage
VDDmin
time
SX8634 ready
Figure 21 Pow er Up vs. INTB
During the po wer on p er iod t he SX8634 stabi lizes th e i nternal regula tors , RC clocks and the f ir mware in itiali z es a ll
registers.
During the power up the SX8634 is not accessible and I2C communications are forbidden.
As soon as the INTB rises the SX8634 will be ready for I2C communication.
3.14.2 RESETB
When RESETB is driven low the SX8634 will reset and start the power up sequence as soon as RESETB is
driven high or pulled high.
In case the user does not require a hardware reset control pin then the RESETB pin can be connected to VDD.
VDD
t res
RESETB
time
SX8634 startup
VDD
INTB
time
t por
SX8634 ready
Figure 22 Hardware Reset
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3.14.3 Software Reset
To perform a software reset the host needs to write 0xDE followed by 0x00 at the SoftReset register at address
0xB1.
SoftReset
register
time
SX8634 startup
VDD
INTB
time
t
por
SX8634 ready
0xDE 0x00
Figure 23 Sof t ware Reset
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3.15 Interrupt
3.15.1 Power up
During power up the INTB is kept low. Once the power up sequence is terminated the INTB is released
autonomously. The SX8634 is then ready for operation.
VDD
INTB
time
VDD
t por
supply
voltage
VDDmin
time
SX8634 ready
Figure 24 Pow er Up vs. INTB
During the po wer on p er iod t he SX8634 st a bili zes the interna l reg ula tor s, RC c loc k s and the f irmware init iali z es all
registers.
During the power up the SX8634 is not accessible and I2C communications are forbidden.
As soon as the INTB rises the SX8634 will be ready for I2C communication.
3.15.2 Assertion
INTB is updated in Active or Doze mode once every scan period.
The INTB will be asserted: at the following events:
• if a Button e vent oc curred ( touch or r elease if enab led). I 2C regis ters CapStat Msb and Ca pStatLsb s ho w the
detailed status of the Buttons,
• if a Slider event occurred (touch, release, move high, move low or position change). I2C registers
CapStatMsb, SldPosMsb and SldPosLsb show the detailed status of the Slider,
• if a GPI edge occ urred (rising or falling if enab led). I2C register GpiStat s hows the det ailed status of the GPI
pins,
• when actually entering Active or Doze mode either through automatic wakeup or via host request (may be
delayed by 1 scan period). I2C register CompOpmode shows the current operation mode,
• once compensation procedure is completed either through automatic trigger or via host request (may be
delayed by 1 scan period),
• once SPM write is effective (may be delayed by 1 scan period),
• once NVM burn procedure is completed (may be delayed by 1 scan period),
• during reset (power up, hardware RESETB, software reset).
3.15.3 Clearing
INTB is updated in Active or Doze mode once every scan period.
The clearing of the INTB is done as soon as the host performs a read to the IrqSrc I2C register or reset is
completed
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3.15.4 Example
A typical example of the assertion and clearing of the INTB and the I2C communication is shown in Figure 25.
off on on off
INTB
time
I2C
1
2
3
4
read read
Figure 25 I nt errupt and I2C
When a button is touched the SX8634 will assert the interrupt (1). The host will read the IrqSrc information over
the I2C and this clears the interrupt (2).
If the f inger r eleases the bu tton the inter ru pt will be as s er ted ( 3). The host reading the Ir qSrc inf orm ation wil l clear
the interrupt (4).
In case the host does not react to an interrupt this results in a missing touch.
3.16 General Purpose Input and Outputs
3.16.1 Introduction and Definitions
The SX8634 off ers eight General P urpos e Inp ut a nd O utputs ( GPIO ) p ins whic h can be c o nf igur e d i n any of these
modes:
- GPI (General Purpose Input)
- GPP (General Pur p ose P WM)
- GPO (General Purpose Output)
Each of these modes is described in more details in the following sections.
The polarit y of the GPP and GPO pins is defined as in figure below, driving an L ED as example. It has to be set
accordingly in SPM parameter GpioPolarity.
gpio
gpio
vdd
(a) (b)
Figure 26 Po lar it y definition, (a) normal, (b) inverted
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The PWM blocks used in GPP and GPO modes are 8-bits based and clocked at 2MHz typ. hence offering 256
selectable pulse width values with a granularity of 128us typ.
time
VDD
(a)
period
width
time
VDD
(b)
period
width
Figure 27 PWM definition, (a) small pulse width, (b) large pulse width
3.16.2 GPI
GPIOs configured as GPI will operate as digital inputs with standard low and high logic levels.
Optional pull-up/down and debounce can be enabled. Each GPI is individually edge programmable for INTB
generation which will also exit Sleep/Doze mode if relevant.
SPM/I2C parameters applicable in GPI mode are listed in table below. Please refer to the relevant SPM/I2C
parameters sections for more details.
GPI
SPM
GpioMode
X
GpioPullUpDown
X
GpioInterrupt
X
GpioDebounce
X
I2C
IrqSrc[4]
X
GpiStat
X
Table 7 SPM/I2C Param eters Applicable in GPI Mode
3.16.3 GPP
GPIOs configured as GPP will operate as PWM outputs directly controlled by the host. A typical application is
LED dimm ing.
Typical GPP operation is illustrated in figure below.
I2C
0% 50% 100%
SX8634HOST SX8634HOST
GppIntensity = 0x7F
I2C
GppIntensity = 0xFF
Figure 28 LED control in GPP mode
SPM/I2C parameters applicable in GPP mode are listed in table below. Please refer to the relevant SPM/I2C
parameters sections for more details.
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GPP
SPM
GpioMode
X
GpioOutPwrUp
X1
GpioPolarity
X
GpioIntensityOn
X1
GpioIntensityOff
X1
GpioFunction
X
I2C
GppPinId
X
GppIntensity
X1
1 At power up, GppIntensity of each GPP pin is initialized with GpioIntensityOn or Gpi oIntensityOff depending on GpioOutPwrUp
corresponding bits value.
Table 8 SPM/I2C Param eters Applicable in GPP Mode
3.16.4 GPO
GPIOs configured as GPO will operate as digital outputs which can generate both standard low/high logic levels
and PWM low/high duty cycles levels. Typical application is LED ON/OFF control.
Transitions between ON and OFF states can be triggered either automatically in Autolight mode or manually by
the host. This is illustrated in figures below.
I2C
OFF ON OFF
SX8634HOST SX8634HOST
GpoCtrl = 1
I2C
GpoCtrl = 0
Figure 29 LED Control in GPO mode, Autolight O FF
OFF ON OFF
Figure 30 LED Control in GPO mode, Autolight ON (mapped to Button)
Addition ally these tra nsitions c an be configured to be done with or without fadin g following a logarithm ic or linear
function. This is illustrated in figures below.
time
PWM pulse width
intensity ON
intensity OFF
fading steps
inc. time
time
intensity ON
intensity OFF
fading steps
inc. time
(a) (b)
trigger trigger
PWM pulse width
Figure 31 G PO O N transition (LED fade in), normal polarity, (a) linear, (b) logarithmic
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time
intensity ON
intensity OFF
fading steps
inc. time
time
intensity ON
intensity OFF
fading steps
inc. time
(a) (b)
trigger trigger
PWM pulse width
PWM pulse width
Figure 32 G PO O N transition (LED fade in), inverted polarity, (a) linear, (b) logarithmic
The fading o ut (e.g. af ter a button is release d) is ident ical to the f ading in bu t an addit ional off delay can b e added
before the fading starts (Figure 33 and Figure 34).
intensity OFF
intensity ON
fading steps
dec. time
trigger time time
intensity OFF
intensity ON
fading steps
(b)
trigger
off delay
dec. time
off delay
PWM pulse width
PWM pulse width
Figure 33 G PO O FF transition (LED fade out), normal polarity, (a) linear, (b) logarithmic
time
intensity OFF
intensity ON
fading steps
dec. time
(a)
trigger time
intensity OFF
intensity ON
fading steps
dec. time
(b)
trigger
off delay
off delay
PWM pulse width
PWM pulse width
Figure 34 G PO O FF transition (LED fade out), inverted polarity, (a) linear, (b) logarit hmic
Please n ote tha t stan dard high/l ow log ic sig nals are ju st a spec ific c ase of G PO m ode and c an a lso be g ener ated
simply by setting inc/dec time to 0 (ie OFF) and programming intensity OFF/ON to 0x00 and 0xFF.
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SPM/I2C parameters applicable in GPO mode are listed in table below.
GPO
SPM
GpioMode
X
GpioOutPwrUp
X1
GpioAutoligth
X
GpioPolarity
X
GpioIntensityOn
X
GpioIntensityOff
X
GpioFunction
X
GpioIncFactor
X
GpioDecFactor
X
GpioIncTime
X
GpioDecTime
X
GpioOffDelay
X
I2C
GpoCtrl
X2
1 Only if Autolight is OFF, else must be left to 0 (default value)
2 Only if Autolight is OFF, else ignored
Table 9 SPM/I2C Parameters Applicable in GPO Mode
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3.16.5 Intensity index vs PWM pulse width
Tables below are used to convert all intensity indexes parameters GpioIntensityOff, GpioIntensityOn and
GppIntensity but also to generate fading in GPO mode
During fading in(out), the index is automatically incremented(decremented) at every Inc(Dec)Time x
Inc(Dec)Factor until it reaches the programmed GpioIntensityOn(Off) value.
Index
Lin/Log
Index
Lin/Log
Index
Lin/Log
Index
Lin/Log
Index
Lin/Log
Index
Lin/Log
Index
Lin/Log
Index
Lin/Log
0
0/0
32
33/5
64
65/12
96
97/26
128
129/48
160
161/81
192
193/125
224
225/184
1
2/0
33
34/5
65
66/13
97
98/27
129
130/49
161
162/82
193
194/127
225
226/186
2
3/0
34
35/5
66
67/13
98
99/27
130
131/50
162
163/83
194
195/129
226
227/188
3
4/0
35
36/5
67
68/13
99
100/28
131
132/51
163
164/84
195
196/130
227
228/190
4
5/0
36
37/5
68
69/14
100
101/29
132
133/52
164
165/86
196
197/132
228
229/192
5
6/2
37
38/6
69
70/14
101
102/29
133
134/53
165
166/87
197
198/133
229
230/194
6
7/2
38
39/6
70
71/14
102
103/30
134
135/54
166
167/88
198
199/135
230
231/197
7
8/2
39
40/6
71
72/15
103
104/30
135
136/55
167
168/89
199
200/137
231
232/199
8
9/2
40
41/6
72
73/15
104
105/31
136
137/55
168
169/91
200
201/139
232
233/201
9
10/2
41
42/6
73
74/15
105
106/32
137
138/56
169
170/92
201
202/140
233
234/203
10
11/2
42
43/7
74
75/16
106
107/32
138
139/57
170
171/93
202
203/142
234
235/205
11
12/2
43
44/7
75
76/16
107
108/33
139
140/58
171
172/95
203
204/144
235
236/208
12
13/2
44
45/7
76
77/16
108
109/33
140
141/59
172
173/96
204
205/146
236
237/210
13
14/2
45
46/7
77
78/17
109
110/34
141
142/60
173
174/97
205
206/147
237
238/212
14
15/3
46
47/7
78
79/17
110
111/35
142
143/61
174
175/99
206
207/149
238
239/215
15
16/3
47
48/8
79
80/18
111
112/35
143
144/62
175
176/100
207
208/151
239
240/217
16
17/3
48
49/8
80
81/18
112
113/36
144
145/63
176
177/101
208
209/153
240
241/219
17
18/3
49
50/8
81
82/19
113
114/37
145
146/64
177
178/103
209
210/155
241
242/221
18
19/3
50
51/8
82
83/19
114
115/38
146
147/65
178
179/104
210
211/156
242
243/224
19
20/3
51
52/9
83
84/20
115
116/38
147
148/66
179
180/106
211
212/158
243
244/226
20
21/3
52
53/9
84
85/20
116
117/39
148
149/67
180
181/107
212
213/160
244
245/229
21
22/3
53
54/9
85
86/21
117
118/40
149
150/68
181
182/109
213
214/162
245
246/231
22
23/3
54
55/9
86
87/21
118
119/40
150
151/69
182
183/110
214
215/164
246
247/233
23
24/4
55
56/10
87
88/22
119
120/41
151
152/71
183
184/111
215
216/166
247
248/236
24
25/4
56
57/10
88
89/22
120
121/42
152
153/72
184
185/113
216
217/168
248
249/238
25
26/4
57
58/10
89
90/23
121
122/43
153
154/73
185
186/114
217
218/170
249
250/241
26
27/4
58
59/10
90
91/23
122
123/44
154
155/74
186
187/116
218
219/172
250
251/243
27
28/4
59
60/11
91
92/24
123
124/44
155
156/75
187
188/117
219
220/174
251
252/246
28
29/4
60
61/11
92
93/24
124
125/45
156
157/76
188
189/119
220
221/176
252
253/248
29
30/4
61
62/11
93
94/25
125
126/46
157
158/77
189
190/121
221
222/178
253
254/251
30
31/4
62
63/12
94
95/25
126
127/47
158
159/78
190
191/122
222
223/180
254
255/253
31
32/5
63
64/12
95
96/26
127
128/48
159
160/80
191
192/124
223
224/182
255
256/256
Table 10 Intensity index vs. PWM pulse width (normal polarity)
Index
Lin/Log
Index
Lin/Log
Index
Lin/Log
Index
Lin/Log
Index
Lin/Log
Index
Lin/Log
Index
Lin/Log
Index
Lin/Log
0
256/256
32
224/251
64
192/244
96
160/230
128
128/208
160
96/175
192
64/131
224
32/72
1
255/256
33
223/251
65
191/243
97
159/229
129
127/207
161
95/174
193
63/129
225
31/70
2
254/256
34
222/251
66
190/243
98
158/229
130
126/206
162
94/173
194
62/127
226
30/68
3
253/256
35
221/251
67
189/243
99
157/228
131
125/205
163
93/172
195
61/126
227
29/66
4
252/256
36
220/251
68
188/242
100
156/227
132
124/204
164
92/170
196
60/124
228
28/64
5
251/254
37
219/250
69
187/242
101
155/227
133
123/203
165
91/169
197
59/123
229
27/62
6
250/254
38
218/250
70
186/242
102
154/226
134
122/202
166
90/168
198
58/121
230
26/59
7
249/254
39
217/250
71
185/241
103
153/226
135
121/201
167
89/167
199
57/119
231
25/57
8
248/254
40
216/250
72
184/241
104
152/225
136
120/201
168
88/165
200
56/117
232
24/55
9
247/254
41
215/250
73
183/241
105
151/224
137
119/200
169
87/164
201
55/116
233
23/53
10
246/254
42
214/249
74
182/240
106
150/224
138
118/199
170
86/163
202
54/114
234
22/50
11
245/254
43
213/249
75
181/240
107
149/223
139
117/198
171
85/161
203
53/112
235
21/48
12
244/254
44
212/249
76
180/240
108
148/223
140
116/197
172
84/160
204
52/110
236
20/46
13
243/254
45
211/249
77
179/239
109
147/222
141
115/196
173
83/159
205
51/109
237
19/44
14
242/253
46
210/249
78
178/239
110
146/221
142
114/195
174
82/157
206
50/107
238
18/41
15
241/253
47
209/248
79
177/238
111
145/221
143
113/194
175
81/156
207
49/105
239
17/39
16
240/253
48
208/248
80
176/238
112
144/220
144
112/193
176
80/155
208
48/103
240
16/37
17
239/253
49
207/248
81
175/237
113
143/219
145
111/192
177
79/153
209
47/101
241
15/35
18
238/253
50
206/248
82
174/237
114
142/218
146
110/191
178
78/152
210
46/100
242
14/32
19
237/253
51
205/247
83
173/236
115
141/218
147
109/190
179
77/150
211
45/98
243
13/30
20
236/253
52
204/247
84
172/236
116
140/217
148
108/189
180
76/149
212
44/96
244
12/27
21
235/253
53
203/247
85
171/235
117
139/216
149
107/188
181
75/147
213
43/94
245
11/25
22
234/253
54
202/247
86
170/235
118
138/216
150
106/187
182
74/146
214
42/92
246
10/23
23
233/252
55
201/246
87
169/234
119
137/215
151
105/185
183
73/145
215
41/90
247
9/20
24
232/252
56
200/246
88
168/234
120
136/214
152
104/184
184
72/143
216
40/88
248
8/18
25
231/252
57
199/246
89
167/233
121
135/213
153
103/183
185
71/142
217
39/86
249
7/15
26
230/252
58
198/246
90
166/233
122
134/212
154
102/182
186
70/140
218
38/84
250
6/13
27
229/252
59
197/245
91
165/232
123
133/212
155
101/181
187
69/139
219
37/82
251
5/10
28
228/252
60
196/245
92
164/232
124
132/211
156
100/180
188
68/137
220
36/80
252
4/8
29
227/252
61
195/245
93
163/231
125
131/210
157
99/179
189
67/135
221
35/78
253
3/5
30
226/252
62
194/244
94
162/231
126
130/209
158
98/178
190
66/134
222
34/76
254
2/3
31
225/251
63
193/244
95
161/230
127
129/208
159
97/176
191
65/132
223
33/74
255
0/0
Table 11 Int ens ity index vs. PWM pulse width (inverted polarity)
Recommended/default settings are inverted polarity (to take advantage from high sink current capability) and
logarithmic mode (due to the non-linear response of the human eye).
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3.17 Smart Wake Up
The SX8634 off ers a sm art wake up m echanism (up t o 6 ke ys) which al lows wak ing-up from the Do ze low po wer
mode to the Active mode in a secure/controlled way and not by any unintentional sensor activation.
Until the f ull correct wak e-up sequence is enter ed, the SX8634 will rem ain in Doze m ode. Any wrong k ey im plies
the whole sequence to be entered again.
Please note that each key touch must be followed by a release to be validated.
Hence if a proximity sensor and a touch button part of the wake-up sequence are interleaved on the PCB (ie if you
cannot touch the button without triggering proximity detection) the smart wake up feature cannot be used since
the proximity sensor is not “released” before the buttons are touched. In this case the smart wakeup sequence
must be turned OFF.
The smart wake-up mechanism can also be disabled which implies that Doze mode can hence only be exited
from GPI or I2C command.
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4 PIN DESCRIPTIONS
4.1 Introduction
This chapter describes briefly the pins of the SX8634, the way the pins are protected, if the pins are analog,
digital, require pull up or pull down resistors and show control signals if these are available.
4.2 ASI pins
CAP0, CAP1, ..., CAP11
The capac itance sens or pins (CAP0, CA P1, ..., CA P11) are c onnected directly to the ASI c ircuitr y which con verts
the sensed capacitance into digital values.
The capacitance sensor pins which are not used should be left open.
The enabled CAP pins need be connected directly to the sensors without significant resistance (typical below
some ohms, connection vias are allowed).
The capacitance sensor pins are protected to VANA and GROUND.
Figure 35 shows the simplified diagram of the CAP0, CAP1, ..., CAP11 pins.
SX8634
sensor
ASI
CAPx
CAP_INx
VANA
Note : x = 0, 1,2,…11
Figure 35 S im plified diagram of CAP0, CAP1, ..., CAP11
CN, CP
The CN and the C P pins are connec ted to th e ASI circuitr y. A 1nF sam pling c apac itor betw een CP an d CN needs
to be placed as close as possible to the SX8634.
The CN and CP are protected to VANA and GROUND.
Figure 36 shows the simplified diagram of the CN and CP pins.
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SX8634
ASI
CP
VANA
CN
VANA
Figure 36 S im plified diagram of CN and CP
4.3 Host interface pins
The host interface consists of the interrupt pin INTB, a reset pin RESETB and the standard I2C pins: SCL and
SDA.
INTB
The INTB pin is an open drain output that requires an external pull-up resistor (1..10 kOhm). The INTB pin is
protected to VDD using dedicated devices. The INTB pin has diode protected to GROUND.
Figure 37 shows a simplified diagram of the INTB pin.
VDD
R_INT
INTB
SX8634
INT
to host
Figure 37 S im plified diagram of INTB
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SCL
The SCL pi n is a h igh impedance in put p in. T he SCL pin is pr o tec ted to V DD , us in g de dica ted de v ic es , in ord er to
conform to standard I2C slave specifications. The SCL pin has diode protected to GROUND.
An external pull-up resistor (1..10 kOhm) is required on this pin.
Figure 38 shows the simplified diagram of the SCL pin.
VDD
R_SCL
SCL
SX8634
from host
SCL_IN
Figure 38 S im plified diagram of SCL
SDA
SDA is an IO pin that can be used as an open drain output pin with external pull-up resistor or as a high
impedance input pin. The SDA IO pin is protected to VDD, using dedicated devices, in order to conform to
standard I2C slave specifications. The SDA pin has diode protected to GROUND.
An external pull-up resistor (1..10 kOhm) is required on this pin.
Figure 39 shows the simplified diagram of the SDA pin.
VDD
R_SDA
SDA
SX8634
SDA_OUT
from/to host
SDA_IN
Figure 39 S im plified diagram of SDA
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RESETB
The RESETB pin is a high impedance input pin. The RESETB pin is protected to VDD using dedicated devices.
The RESETB pin has diode protected to GROUND.
Figure 40 shows the simplified diagram of the RESETB pin controlled by the host.
VDD
R_RESETB
RESETB
SX8634
from host
RESETB_IN
Figure 40 S im plified diagram of RESETB controlled by host
Figure 41 shows the RESETB without host control.
VDD
RESETB
SX8634
RESETB_IN
Figure 41 S im plified diagram of RESETB without host control
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4.4 Power management pins
The power management pins consist of the Power, Ground and Regulator pins.
VDD
VDD is a power pin and is the main power supply for the SX8634.
VDD has protection to GROUND.
Figure 42 shows a simplified diagram of the VDD pin.
VDD
SX8634
VDD
Figure 42 S im plified diagram of VDD
GND
The SX8634 has four ground pins all nam ed GND . These pins and the package c enter pa d need to b e connec ted
to ground pot ent ial .
The GND has protection to VDD.
Figure 43 shows a simplified diagram of the GND pin.
VDD
SX8634
GND
GND
Figure 43 S im plified diagram of GND
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VANA, VDIG
The SX8634 has on-chip regulators for internal use (pins VA NA a nd VDI G ).
VANA and VDIG have protection to VDD and to GND.
The output of the regulators needs to be de-coupled with a small 100nF capacitor to ground.
Figure 44 shows a simplified diagram of the VANA and VDIG pin.
VDD
SX8634
GND
VDIG
VDD
GND
VANA
VANA
VDIG
Cvdig
Cvana
Figure 44 S im plified diagram of VANA and VDIG
4.5 General purpose IO pins
The SX8634 has 8 General purpose input/output (GPIO) pins.
All the GPIO pins ha ve pr ot ec tion to VDD and GND.
The GPIO pins can be configured as GPI, GPO or GPP.
Figure 45 shows a simplified diagram of the GPIO pins.
SX8634
VDD Rup
ctrl
Rdown
GPIO7...0
ctrl
GPO,
GPP
VDD
PWM
GPI
GPO,
GPP
VDD
Figure 45 S im plified diagram of GPIO pin s
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5 DETAILED CONFIGURATION DESCRIPTIONS
5.1 Introduction
The SX8634 configuration parameters are tak en fr om the QSM or the N VM and l oade d i nto th e S PM as explained
in the chapter ‘functional description’.
This chapter describes the details of the configuration parameters of the SX8634.
.
The SPM is split by functionality into 6 configuration sections:
• General section: operating modes,
• Capaciti ve Sens or s section: related to lower level capacitive sensing,
• Button: related to the conversion from sensor data towards button information,
• Slider: related to the conversion from sensor data towards slider information,
• Mapping: related to mapping of button and slider information towards wake-up and GPIO pins,
• GPIO: related to the setup of the GPIO pins.
The total address space of the SPM and the NVM is 128 bytes, from address 0x00 to address 0x7F.
Two types of memory addresses, data are accessible to the user.
• ‘application data’: Application dependent data that need to be configured by the user.
• ‘reserved’: Data that need to be maintained by the user to the QSM default values (i.e. when NVM is burned).
The Table 12 and Table 13 resume the complete SPM address space and show the ‘application data’ and
‘reserved’ addresses, the functional split and the default values (loaded from the QSM).
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Address Name default QSM
value Address Name default QSM
value
0x00
Reserved
0xxx
0x20
Reserved
0x00
0x01 Reserved 0xxx 0x21
Button
BtnCfg 0x30
0x02 Reserved 0x11 0x22 BtnAvgThresh 0x50
0x03 Reserved 0xxx 0x23 BtnCompNegThresh 0x50
0x04
General
I2CAddress
0x2B
0x24
BtnCompNegCntMax
0x01
0x05
ActiveScanPeriod
0x02
0x25
BtnHysteresis
0x0A
0x06 DozeScanPeriod 0x0D 0x26 BtnStuckAtTimeout 0x00
0x07 PassiveTimer 0x00 0x27
Slider
SldCfg 0x00
0x08 Reserved 0x00 0x28 SldStuckAtTimeout 0x00
0x09
Capacitive Sensors
CapModeMisc 0x01 0x29 SldHysteresis 0x03
0x0A
CapMode11_8
0xAA
0x2A
Reserved
0xFF
0x0B CapMode7_4 0xA5 0x2B SldNormMsb 0x01
0x0C CapMode3_0 0x55 0x2C SldNormLsb 0x80
0x0D CapSensitivity0_1 0x00 0x2D SldAvgThresh 0x50
0x0E CapSensitivity2_3 0x00 0x2E SldCompNegThresh 0x50
0x0F
CapSensitivity4_5
0x00
0x2F
SldCompNegCntMax
0x01
0x10 CapSensitivity6_7 0x00 0x30 SldMoveThresh 0x02
0x11 CapSensitivity8_9 0x00 0x31 Reserved 0x00
0x12 CapSensitivity10_11 0x00 0x32 Reserved 0x00
0x13
CapThresh0
0xA0
0x33
Mapping
MapWakeupSize
0x00
0x14
CapThresh1
0xA0
0x34
MapWakeupValue0
0x00
0x15
CapThresh2
0xA0
0x35
MapWakeupValue1
0x00
0x16 CapThresh3 0xA0 0x36 MapWakeupValue2 0x00
0x17 CapThresh4 0xA0 0x37 MapAutoLight0 0xFE
0x18 CapThresh5 0xA0 0x38 MapAutoLight1 0x54
0x19
CapThresh6
0xA0
0x39
MapAutoLight2
0x32
0x1A CapThresh7 0xA0 0x3A MapAutoLight3 0x10
0x1B CapThresh8 0xA0 0x3B MapAutoLightGrp0Msb 0x00
0x1C CapThresh9 0xA0 0x3C MapAutoLightGrp0Lsb 0x00
0x1D CapThresh10 0xA0 0x3D MapAutoLightGrp1Msb 0x00
0x1E
CapThresh11
0xA0
0x3E
MapAutoLightGrp1Lsb
0x00
0x1F CapPerComp 0x00 0x3F MapSegmentHysteresis 0x02
Table 12 SPM address map: 0x00…0x3F
Note
• ‘0xxx’: write protected data
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Address Name default QSM
value Address Name
default QSM
value
0x40
Gpio
GpioMode7_4
0x00
0x60
Gpio
GpioDecTime1_0
0x44
0x41 GpioMode3_0 0x00 0x61 GpioOffDelay7_6 0x00
0x42 GpioOutPwrUp 0x00 0x62 GpioOffDelay5_4 0x00
0x43 GpioAutoLight 0xFF 0x63 GpioOffDelay3_2 0x00
0x44 GpioPolarity 0x00 0x64 GpioOffDelay1_0 0x00
0x45
GpioIntensityOn0
0xFF
0x65
GpioPullUpDown7_4
0x00
0x46 GpioIntensityOn1 0xFF 0x66 GpioPullUpDown3_0 0x00
0x47 GpioIntensityOn2 0xFF 0x67 GpioInterrupt7_4 0x00
0x48 GpioIntensityOn3 0xFF 0x68 GpioInterrupt3_0 0x00
0x49
GpioIntensityOn4
0xFF
0x69
GpioDebounce
0x00
0x4A
GpioIntensityOn5
0xFF
0x6A
Reserved
0x00
0x4B
GpioIntensityOn6
0xFF
0x6B
Reserved
0x00
0x4C GpioIntensityOn7 0xFF 0x6C Reserved 0x00
0x4D GpioIntensityOff0 0x00 0x6D Reserved 0x00
0x4E GpioIntensityOff1 0x00 0x6E Reserved 0x00
0x4F
GpioIntensityOff2
0x00
0x6F
Reserved
0x50
0x50 GpioIntensityOff3 0x00 0x70 CapProxEnable 0x46
0x51 GpioIntensityOff4 0x00 0x71 Reserved 0x10
0x52 GpioIntensityOff5 0x00 0x72 Reserved 0x45
0x53 GpioIntensityOff6 0x00 0x73 Reserved 0x02
0x54
GpioIntensityOff7
0x00
0x74
Reserved
0xFF
0x55 Reserved 0xFF 0x75 Reserved 0xFF
0x56 GpioFunction 0x00 0x76 Reserved 0xFF
0x57 GpioIncFactor 0x00 0x77 Reserved 0xD5
0x58 GpioDecFactor 0x00 0x78 Reserved 0x55
0x59
GpioIncTime7_6
0x00
0x79
Reserved
0x55
0x5A
GpioIncTime5_4
0x00
0x7A
Reserved
0x7F
0x5B GpioIncTime3_2 0x00 0x7B Reserved 0x23
0x5C GpioIncTime1_0 0x00 0x7C Reserved 0x22
0x5D GpioDecTime7_6 0x44 0x7D Reserved 0x41
0x5E
GpioDecTime5_4
0x44
0x7E
Reserved
0xFF
0x5F GpioDecTime3_2 0x44 0x7F SpmCrc* 0x6F
Table 13 SPM address map: 0x40…0x7F
Note*
• SpmCrc: CRC depending on SPM content, updated in Active or Doze mode.
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5.2 General Parameters
General Parameters
Address Name Bits Description
0x04
I2CAddress
7
Reserved
6:0
Defines the I2C address (default 0x2B).
The I2C address will be active after a reset.
0x05
ActiveScanPeriod
7:0
Active Mode Scan Period (Figure 7)
0x00: Reserved
0x01: 15ms
0x02: 30ms (default)
…
0xFF: 255 x 15ms
0x06
DozeScanPeriod
7:0
Doze Mode Scan Period (Figure 7)
0x00: Reserved
0x01: 15ms
…
0x0D: 195ms (default)
…
0xFF: 255 x 15ms
0x07
PassiveTimer
7:0
Passive Timer on Button and Slider Information (Figure 8)
0x00: OFF (default)
0x01: 1 second
…
0xFF: 255 seconds
Table 14 Gener al Param eter s
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5.3 Capacitive Sensors Parameters
Capacitive Sensors Parameters
Address Name Bits Description
0x09
CapModeMisc
7:3
Reserved
2:0
IndividualSensitivity
Defines common sensitivity for all sensors or individual
sensor sen si tiv i ty .
001: Common settings (CapSensitivity0_1[7:4])
100: Individual CAP sensitivity settings (CapSensitivityx_x)
Else : Reserved
0x0A
CapMode11_8
7:6
CAP11 Mode
Defines the mode of
the CAP pin.
00: Disabled
01: Button
10: Slider
11: Reserved
Default
Slider
5:4
CAP10 Mode
Slider
3:2
CAP9 Mode
Slider
1:0
CAP8 Mode
Slider
0x0B
CapMode7_4
7:6
CAP7 Mode
Slider
5:4
CAP6 Mode
Slider
3:2
CAP5 Mode
Button
1:0
CAP4 Mode
Button
0x0C
CapMode3_0
7:6
CAP3 Mode
Button
5:4
CAP2 Mode
Button
3:2
CAP1 Mode
Button
1:0
CAP0 Mode
Button
0x0D
CapSensitivity0_1
7:4
CAP0 Sensitivity - Common Sensitivity
Defines the sensitivity.
0x0: Minimum (default)
0x7: Maximum
0x8…0xF: Reserved
3:0
CAP1 Sensitivity
0x0E
CapSensitivity2_3
7:4
CAP2 Sensitivity
3:0
CAP3 Sensitivity
0x0F
CapSensitivity4_5
7:4
CAP4 Sensitivity
3:0
CAP5 Sensitivity
0x10
CapSensitivity6_7
7:4
CAP6 Sensitivity
3:0
CAP7 Sensitivity
0x11
CapSensitivity8_9
7:4
CAP8 Sensitivity
3:0
CAP9 Sensitivity
0x12
CapSensitivity10_11
7:4
CAP10 Sensitivity
3:0
CAP11 Sensitivity
0x13
CapThresh0
7:0
CAP0 Touch Threshold
Defines the Touch Threshold ticks.
0x00: 0,
0x01: 4,
…
0xA0: 640 (default),
…
0xFF: 1020
0x14
CapThresh1
7:0
CAP1 Touch Threshold
0x15
CapThresh2
7:0
CAP2 Touch Threshold
0x16
CapThresh3
7:0
CAP3 Touch Threshold
0x17
CapThresh4
7:0
CAP4 Touch Threshold
0x18
CapThresh5
7:0
CAP5 Touch Threshold
0x19
CapThresh6
7:0
CAP6 Touch Threshold
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Capacitive Sensors Parameters
Address Name Bits Description
0x1A
CapThresh7
7:0
CAP7 Touch Threshold
0x1B
CapThresh8
7:0
CAP8 Touch Threshold
0x1C
CapThresh9
7:0
CAP9 Touch Threshold
0x1D
CapThresh10
7:0
CAP10 Touch Threshold
0x1E
CapThresh11
7:0
CAP11 Touch Threshold
0x1F
CapPerComp
7:4
Reserved
3:0
Periodic Offset Compensation
Defines the periodic offs et co mpen sat ion.
0x0: OFF (default)
0x1: 1 second
0x2: 2 seconds
…
0x7: 7 seconds
0x8: 16 seconds
0x9: 18 seconds
…
0xE: 28 seconds
0xF: 60 seconds
0x70
CapProxEnable
7:0
Enables proximity sensing:
0x46: OFF
0x74: ON
Table 15 Capacitive Sensors Parameters
CapModeMisc
By default th e A SI is us in g a c om m on s ensitiv ity f or al l c apaciti ve sens or s as in t h e us ual cas e o verl a y m ateri al
and sensors sizes are about equal. The register bits CapSensitivity0_1[7:4] determine the sensitivity for all
sensors in common sensitivity mode.
It might be required to have a different, individual, sensitivity for each CAP pin (for example proximity sensor
set to max sensitivity while touch sensors are set to a lower one). This can be obtained by setting
CapModeMisc[2:0] to “100” The individual sensitivity mode results in longer sensing periods than required in
common sensitivity mode.
CapMode11_8, CapMode7_4, CapMode3_0:
The CAP pins can be set as a button, part of a slider or disabled depending on the application.
minimum default maximum
buttons zero six eight
slider one
(of four sensors) one
(of six sensors) one
(of twelve sensors)
Table 16 Possible CAP pin modes
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Buttons and disabled CAP pins can be attributed freely (examples in Figure 46). All buttons can be used for
touch or proximity sensing, in the latter case register CapProxEnable needs to be set accordingly .
SX8634
cap1 (button1)
cap4 (disabled)
cap2 (button2)
cap3 (button3)
cap5 (disabled)
cap6 (disabled)
SX8634
cap1 (button1)
cap6 (button6)
cap3 (button3)
cap2 (disabled)
cap4 (disabled)
cap5 (disabled)
Figure 46 Button examples
Disabled CAP pins inside the slider sensor attribution sequence are allowed, but CAP buttons inside a slider
are not allowed (see example Figure 47 with CAP3 in a correct and a not allowed configuration).
SX8634
cap1 (button1)
cap2 (sld0)
cap3 (disabled)
cap4 (sld1)
cap5 (sld2)
cap6 (sld3)
SX8634
cap2 (sld0)
cap3 (button3)
cap4 (sld1)
cap5 (sld2)
cap6 (sld3)
min
max
Figure 47 But t on and Slider good/bad configuration examples (I)
The physical order of the slider sensors on the PCB should cor res pon d to the incr emental CAP pin numbers.
Crossing slider PCB sensors and CAP number is not allowed. Figure 48 sh o ws a valid conf ig urat ion and a
wrong configuration where CAP5 andCAP6 are not routed correctly on the PCB.
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SX8634
cap2 (sld0)
cap3 (disabled)
cap4 (sld1)
cap5 (sld2)
cap6 (sld3)
SX8634
cap2 (sld0)
cap3 (disabled)
cap4 (sld1)
cap5 (sld2)
cap6 (sld3)
min
max
Figure 48 But t on and Slider good/bad configuration examples (II)
The m inimum position of the slider is associated to the CAP pin, attributed to the slider, with the lowest index
(in Figure 48 this is CAP2).
The maximum position of the slider is ass ociated t o th e CAP pin, at trib uted to th e slider, with the hig hest index
(in Figure 48 this is CAP6).
CapSensitivity0_1, CapSensitivity2_3, CapSensitivity4_5,
CapSensitivity6_7, CapSensitivity8_9, CapSensitivity10_11, CapProxEnable:
The sens itivity of the sens ors c an be set between 8 values . The higher the s ensit iv it y is set t he larg er t he val u e
of the ticks will be.
The minimum sensitivity can be used for thin overlay materials and large sensors, while the maximum
sensitivity is required for thicker overlay and smaller sensors or proximity sensing.
The required sensitivity needs to be determined during a product development phase. Too low sensitivity
settings result in missing touches. Too high sensitivity settings will result in fault detection of fingers hovering
above the touch sensors.
The sens itivit y is ident ical f or al l sensor s in c omm on sensit ivit y mode us ing the bit s CapSens iti vity0_1[7 :4] a nd
can be set individually using register CapModeMisc[2:0].
The maximum number of ticks that can be obtained depends on the selected sensitivity and if proximity
sensing is enabled. This is illustrated in Table 17.
Sensitivity Approximate
Maximum Tick Level
(CapPr o xEnable = OFF)
Approximate
Maximum Tick Level
(CapPr o xEnable = ON)
0
1000
4000
1
2000
8000
2
3000
12000
3
4000
16000
4
5000
20000
5
6000
24000
6
7000
28000
7
8000
32000
Table 17 ASI Maximum Tick Levels
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CapThresh0, CapThresh1, CapThresh2, CapThresh3, CapThresh4, CapThresh5, CapThresh6, CapThresh7,
CapThresh8, CapThresh9, CapThresh10, CapThresh11:
For each CAP pin a threshold level can be set individually.
The threshold levels are used by the SX8634 for making touch and release decisions on e.g. touch or no-
touch.
The details are explained in the sections for buttons and slider.
CapPerComp:
The SX8634 offers a periodic offset compensation for applications which are subject to substantial
environmental changes. The periodic offset compensation is done at a defined interval and only if slider and
buttons are released.
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5.4 Button Parameters
Button Parameters
Address Name Bits Description
0x21
BtnCfg
7:6
Defines the buttons events reporting method.
00: Multiple reporting of all touches and releases (default)
01: Single reporting of the first button touch. Next button touches and releases are
ignored until release of the first button.
10: Reserved
11: Reserved
5:4
Defines the buttons interrupt (for all buttons)
00 : Interrupts masked
01 : Triggered on Touch
10 : Triggered on Release
11 : Triggered on Touch and Release (default)
3:2
Defines the number of samples at the scan period for determining a release
00: OFF, use incoming sample (defau lt)
01: 2 samples debounce
10: 3 samples debounce
11: 4 samples debounce
1:0
Defines the number of samples at the scan period for determining a touch
00: OFF, use incoming sample (defau lt)
01: 2 samples debounce
10: 3 samples debounce
11: 4 samples debounce
0x22
BtnAvgThresh
7:0
Defines the positive threshold for disabling the processing filter averaging.
If ticks are above the threshold, then the averaging is suspended
0x00: 0
0x01: 4
…
0x50: 320 (default)
…
0xFF: 1020
0x23
BtnCompNegThresh
7:0
Defines the negativ e offs et co mpen sat ion thr e sho ld.
0x00: 0
0x01: 4
…
0x50: 320 (default)
…
0xFF: 1020
0x24
BtnCompNegCntMax
7:0
Defines the number of ticks (below the negative offset compensation threshold)
which will initiate an offset compensation.
0x00: Reserved
0x01: 1 sample (def ault )
…
0xFF-> samples
0x25
BtnHysteresis
7:0
Defines the button hysteresis corresponding to a percentage of the CAP thresholds
(defined in Table 18).
0x00: 0%
…
0x0A: 10% (default)
…
0x64: 100%
All buttons use the same hysteresis
0x26
BtnStuckAtTimeout
7:0
Defines the stuck at timeout.
0x00: OFF (default)
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Button Parameters
Address Name Bits Description
0x01: 1 second
…
0xFF: 255 seconds
Table 18 Butt on Conf iguration Parameters
Please not e that proxim it y sensors are conf igured as buttons and oper ate exactly the sam e wa y as touch buttons .
All the parameters and procedures described below apply similarly .
A reliable button operation requires a coherent setting of the registers.
Figure 49 shows an example of a touch and a release. The ticks will vary slightly around the zero idle state.
When the touch occurs the ticks will rise sharply. At the release of the button the ticks will go down rapidly and
converge to the idle zero value.
time
0
ticks_diff
BtnHysteresis
BtnHysteresis
= no-touch
Touch
(touch debounce = 1)
= touch
(release debounce = 0)
Release
CapThreshold
= scan events @ scan period
Figure 49 Touc h and Release Example
As soon as the ticks become larger than the CAP thresholds (see registers of the previous section) plus the
hysteresis (defined in register BtnHysteresis) the debounce counter starts.
In the example of Figure 49 the touch is validated after 2 samples (BtnCfg [1: 0] = 01).
The releas e is detec ted im m ediatel y (BtnCfg [3:2] = 00) at the firs t sample which is below th e thresh old m inus t he
hysteresis.
BtnCfg
The SX8634 can re port a ll t ouc hes of multiple finger s o r the SX8634 can be s et to r epor t on l y the fir st det ect e d
touch. In the later case all succeeding touches are ignored. The very first touch should be released before a
next touch will be detected.
The user can select to have the interrupt signal on touching a button, releasing a button or both
In noisy environments it may be required to debounce the touch and release detection decision.
In case the debounce is enabled the SX8634 will count up to the number of debounce sam ples BtnCfg [1:0],
BtnCfg [3:2] before taking a touch or release decision. The sample period is identical to the scan period.
BtnAvgThresh
Small environmental and system noise cause the ticks to vary slowly around the zero idle mode value.
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In case the ticks get slightly positive this is considered as normal operation. Very large positive tick values
indicate a valid touch. The averaging filter is disabled as soon as the average reaches the value defined by
BtnAvgThresh. This mechanism avoids that a valid touch will be averaged and finally the tick difference
becomes zero.
In case three or more sensors reach the BtnAvgThresh value simultaneously then the SX8634 will start an
offset compensation procedure.
Small environmental and system noise cause the ticks to vary slowly around the zero idle mode value.
In case the ticks get slightly negative this is considered as normal operation. However large negative values will
trigger an offset compensation phase and a new set of DCVs will be obtained.
The decision to trigger a compensation phase based on negative ticks is determined by the value in the register
BtnCompNegThresh and by the number of ticks below the negative thresholds defined in register
BtnCompNegCntMax. An example is shown in Figure 50.
time
0
ticks_diff
CompNegCnt = 1, 2,...
CompNegThreshold
= ticks < CompNegThreshold
= ticks, no-touch
offset
compensation
CompNegCnt > CompNegCntMax
Figure 50 Negative Ticks O ff set Compensation Trigger
BtnCompNegThresh
Small negative ticks are considered as normal operation and will occur very often.
Larger negative ticks however need to be avoided and a convenient method is to trigger an offset
compensation phase. The new set of DCV will assure the idle ticks will be close to zero again.
A trade-off has to be found for the value of this register. A negative threshold too close to zero will trigger a
compensation phase very often. A very negative threshold will never trigger.
BtnCompNegCntMax
As soon as the ticks get smaller than the Negative Threshold the Negative Counter starts to count.
If the counter goes beyond the Negative Counter Max then the offset compensation phase is triggered.
The rec omm ended valu e for this regis ter is ‘ 1’ which m eans that th e off set c ompens ation star ts on the firs t tick
below the negative threshold.
BtnHysteresis
The hysteresis percentage is identical for all buttons.
A touch is detected if the ticks are getting larger as the value defined by:
CapThreshold + CapThreshold * hysteresis.
A release is detected if the ticks are getting smaller as the value defined by:
CapThreshold - CapThreshold * hysteresis.
BtnStuckAtTimeout
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The stuckat timer can avoid sticky buttons.
If the stuckat timer is set to one second then the touch of a finger will last only for one second and then a
compensation will be performed and button hence considered released, even if the finger remains on the
button f or a l ong er time. After the ac tua l f inger r e le as e the b utto n c an be t ouc he d aga in a nd wil l b e rep or ted as
usual.
In case the stuckat timer is not required it can be set to zero.
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5.5 Slider Parameters
Slider Parameters
Address Name Bits Description
0x27
SldCfg
7:4
Reserved
3:2
Defines the number of samples at the scan period for determining a release
00: OFF, use incoming sample (default)
01: 2 samples debounce
10: 3 samples debounce
11: 4 samples debounce
1:0
Defines the number of samples at the scan period for determining a touch
00: OFF, use incoming sample (defau lt)
01: 2 samples debounce
10: 3 samples debounce
11: 4 samples debounce
0x28
SldStuckAtTimeout
7:0
Defines the stuck at timeout.
0x00: OFF (default)
0x01: 1 second
…
0xFF: 255 seconds
0x29
SldHysteresis
7:0
Defines the Slider Touch/Release Hysteresis.
0x00: 0
0x01: 4
…
0x03: 12 (default)
…
0xFF: 1020
0x2B
SldNormMsb
7:0
Slider Norm Msb
Defines the 16 bits slider norm (default 0x0180)
0x2C
SldNormLsb
7:0
Slider Norm Lsb
0x2D
SldAvgThresh
7:0
Defines the positive threshold for disabling the processing filter averaging.
If ticks are above the threshold, then the averaging is suspended
0x00: 0
0x01: 4
…
0x50: 320 (default)
…
0xFF: 1020
0x2E
SldCompNegThresh
7:0
Defines the negativ e offs et co mpen sat ion thr e sho ld.
0x00: 0
0x01: 4
…
0x50: 320 (default)
…
0xFF: 1020
0x2F
SldCompNegCntMax
7:0
Defines the number of ticks (below the negative offset compensation threshold)
which will initiate an offset compensation.
0x00: Reserved
0x01: 1 sample (def ault )
…
0xFF: 255 samples
0x30
SldMoveThresh
7:0
Defines the threshold for detecting a move high or mov e low.
The threshold is a percentage of the maximum slider position.
0x00: 0%
…
0x02: 2% (default)
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Slider Parameters
Address Name Bits Description
…
0x64: 100%
A succeeding position difference, at the scan period, above the threshold is
considered as a move high or move low.
Table 19 Slider Parameters
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The pressure represents the finger touch on the sensors of the slider and it used to determine if a slider is
touched or released.
∑
−
=
−=
1
0
))
(
)(
_(
N
i
i
CapThreshi
diffticks
e
SldPressur
- N is the number of sensors,
- A sensor with ticks smaller than the CapThreshold is not taken into account for calculating the pressure
In case the pressure equals zero the slider status is released.
In case the pressure is larger as the Slider Hysteresis the slider status is touched.
The position of a finger on a slider is calculated by the centre of gravity algorithm.
∑
∑
−
=
−
=
−
−
∗= 1
0
1
0
))()(_(
))()(_(*
32 N
i
N
i
iCapThreshidiffticks
iCapThreshidiffticksi
SldNorm
SldPos
- N is the number of sensors,
- A sensor with ticks smaller than the CapThreshold is not taken into account for calculating the position,
- SldNorm[15:0] is a 16 bit number determined by SldNormMsb[15:8] and SldNormLsb[7:0].
- SldPos is the slider position (16 bits) which can be read by the host over the I2C registers SldPosMsb and
SldPosLsb
....x...
position
CAP0CAP1 CAP5
CAP4
CAP3
CAP2
Figure 51 Slider Position
Figure 51 shows an example of a slider composed of 6 sensors (CAP0, CAP1… CAP5).
The default slider norm value 12 (SldNormMsb = 0x01, SldNormLsb = 0x80), is taken for the example.
A touch on CAP0 gives the s lider pos it ion: 0.
A touch on CAP1 gives the slider position: 12.
A touch on CAP5 gives the slider position: 60.
If a touch occurs on CAP0 and CAP1 the centre of gravity algorithm will interpolate.
Assuming the touch is identically distributed on CAP0 and CAP1 then the position will be: 6
Assuming the touch is identically distributed on CAP1 and CAP2 then the position will be: 18
Assuming the touch is identically distributed on CAP4 and CAP5 then the position will be: 54
The maximum slider position (for this example) that can be obtained is 60.
The minimum position of a slider equals 0.
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The maximum position (SldPosMax) is defined by:
( )
1
32 −×= N
SldNorm
SldPosMax
with:
N is the number of sensors in the slider
Slow varying slider ticks due to environmental changes are handled as buttons in the previous section.
If the ticks pass below the slider negative threshold for more than the compensation negative max counter then an
offset compensation phase will be triggered.
If the ticks pass above the slider average positive threshold then the averaging filters will be held.
A finger that m oves ver y slowl y over the slider is not c onsid ered as a movement. T he status move low and m ove
high will not be set.
A finger that moves faster on the slider will change the movement status.
A movement is detected if the difference of the position for two succeeding samples at the scanning rate goes
beyond the movement threshold (SldMoveThresh). A large movement threshold requires very rapid finger
movements, while a small movement threshold detects more easily movements but gets sensitive to noise
variations as well.
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5.6 Mapping Parameters
Mapping Parameters
Address Name Bits Description
0x33
MapWakeupSize
7:3
Reserved
2:0
Doze -> Active wake up seque nce size.
0: Any sensor event (default)
1: key0
2: key0, key1
…
6: key0, key1, … key 5
7: No sensor event, only GPI or I2C cmd can exit Doze mode
Each key must be followed by a release to be validated.
Any other sensor event before the release is ignored.
Any wrong key implies the whole sequence to be entered again.
0x34
MapWakeupValue0
7:4
key5
Defines the sensor event associated to each key.
0x00: Btn0 (default)
0x01: Btn1
…
0x0B: Btn11
0x0C: Slider Touch
0x0D: Move Low
0x0E: Move High
0x0F: Reserved
3:0
key4
0x35
MapWakeupValue1
7:4
key3
3:0
key2
0x36
MapWakeupValue2
7:4
key1
3:0
key0
0x37
MapAutoLight0
7:4
GPIO[7]
Defines the mapping between GPOs (with
Autolight ON) and sensor events.
0x00: Btn0 (default)
0x01: Btn1
…
0x0B: Btn11
0x0C: Group0 as defined by MapAutoLightGrp0
0x0D: Group1 as defined by MapAutoLightGrp1
0x0E: Move Low
0x0F: Move High
Several GPOs can be mapped to the same
sensor
event and will be controlled simultaneously.
3:0
GPIO[6]
0x38
MapAutoLight1
7:4
GPIO[5]
3:0
GPIO[4]
0x39
MapAutoLight2
7:4
GPIO[3]
3:0
GPIO[2]
0x3A
MapAutoLight3
7:4
GPIO[1]
3:0
GPIO[0]
0x3B
MapAutoLightGrp0Msb
7
Reserved
6
Segment
Defines Group0 sensor events:
0: OFF (default)
1: ON
If any of the enabled sensor events occurs the
Group0 event will occur as well.
All sensors events within the group can be
independently set except slider event Segment
which is exclusive (ie must be the only one
enabled to be used)
5
Move High
4
Move Low
3
Btn11
2
Btn10
1
Btn9
0
Btn8
0x3C
MapAutoLightGrp0Lsb
7
Btn7
6
Btn6
5
Btn5
4
Btn4
3
Btn3
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Mapping Parameters
Address Name Bits Description
2
Btn2
1
Btn1
0
Btn0
0x3D
MapAutoLightGrp1Msb
7
Reserved
6
Slider Touch
Defines Group1 sensor events:
0: OFF (default)
1: ON
If any of the enabled sensor events occurs the
Group0 event will occur as well.
All sensors events within the group can be
independently set.
5
Move High
4
Move Low
3
Btn11
2
Btn10
1
Btn9
0
Btn8
0x3E
MapAutoLightGrp1Lsb
7
Btn7
6
Btn6
5
Btn5
4
Btn4
3
Btn3
2
Btn2
1
Btn1
0
Btn0
0x3F
MapSegmentHysteresis
7:0
Defines the position hysteresis for detecting a segment change.
The hysteresis is defined as a percentage of the maximum slider position.
0x00: 0%
…
0x02: 2% (default)
…
0x64: 100%
This hysteresis applies to all segments of the slider.
Table 20 Mapping Parameters
MapWakeupSize
The number of keys defining the wakeup sequence can be set from 1 to 6.
If the size is set to 0 then wakeup is done on any sensor event.
if the size is set to 6 then wakeup is done onl y b y GPI or an I2C c om m and (m a y be require d if prox im it y sensi ng is
enable, see §3.17 for more details).
MapWakeupValue0, MapWakeupValue1, MapWakeupValue2
For the wakeup sequence Btn2 -> Btn5 -> Btn6 ->Btn0 the required register settings are:
- MapWakeupSize set to 0x04,
- key0 = 0x2
- key1 = 0x5
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=> MapWakeupValue2 set to 0x52
- key2 = 0x6
- key3 = 0x0
=> MapWakeupValue2 set to 0x06
MapAutoLight0, MapAutoLight1, MapAutoLight2, MapAutoLight3
MapAutoLightGrp0Msb, MapAutoLightGrp0Lsb, MapAutoLightGrp1Msb, MapAutoLightGrp1Lsb
These r egist ers d ef ine the mapping bet ween the GPO pins (with Autolight ON) and the sensor information whic h
will control its ON/OFF state.
The mapping can be done to a specific sensor event but also on groups (in this case any sensor event in the
group will control the GPO).
Table 21 defines for each selectable sensor event, which action will trigger corresponding GPO to switch ON
or OFF.
MapAutoLight GPO ON GP O OFF
BtnX
Touch
Release
Slider Touch
Touch
Release
Slider Move High
Move High
Move Low or Release
Slider Move Low
Move Low
Move High or Release
Slider Segment
Segment Touched
Segment Released
Table 21 Autolight Mapping, Sensor Information
Examples:
- If GPO[0] should change state ac c ordi ng l y to Btn4 then MapAutoLight3[3:0] should be set to 0x04.
- If GPO[0] should change state accordingly to Btn0 or Btn1 then Group0 can be used as following:
- MapAutoLight3[3:0] should be set to 0x0C (ie Group0).
- MapAutoLightGrp0 should be set to 0x0003 (ie Btn0 or Btn1)
W hen the Sli der S egment even t is mapped, the num ber of G POs mapped t o it determ ines the number of s lider
segments. The GPO with the lowest pin index is mapped on the segment with the smallest positions.
E.g. if two GPOs (e.g.GPO[0] and GPO[1]) are mapped to the Slider Segment event then the slider is split in
two segments. G PO[0] will tur n O N for a t ouc h on the s lider s egment [0, SldPosMax/2] and GPO[1] for a touc h
on the slider segment [SldPosMax/2, SldPosMax].
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5.7 GPIO Parameters
GPIO Parameters
Address Name Bits Description
0x40
GpioMode7_4
7:6
GPIO[7] Mode
Defines the GPIO mode.
00: GPO (default)
01: GPP
10: GPI
11: Reserved
5:4
GPIO[6] Mode
3:2
GPIO[5] Mode
1:0
GPIO[4] Mode
0x41
GpioMode3_0
7:6
GPIO[3] Mode
5:4
GPIO[2] Mode
3:2
GPIO[1] Mode
1:0
GPIO[0] Mode
0x42
GpioOutPwrUp
7:0
GPIO[7] Output Value at Power Up
Defines the values of GPO and GPP pins
after power up ie default values of I2C
parameters GpoCtrl and GppIntensity
respectively.
0: OFF(GPO) / IntensityOff (GPP) (default)
1: ON (GPO) / IntensityOn (GPP)
Bits corresponding to GPO pins with
Autolight ON should be left to 0.
Before being actually initialized GPIOs are
set as inputs with pull up.
GPIO[6] Output Value at Power Up
GPIO[5] Output Value at Power Up
GPIO[4] Output Value at Power Up
GPIO[3] Output Value at Power Up
GPIO[2] Output Value at Power Up
GPIO[1] Output Value at Power Up
GPIO[0] Output Value at Power Up
0x43
GpioAutoLight
7:0
GPIO[7] AutoLight
Enables Autolight in GPO mode
0 : OFF
1 : ON (default)
GPIO[6] AutoLight
GPIO[5] AutoLight
GPIO[4] AutoLight
GPIO[3] AutoLight
GPIO[2] AutoLight
GPIO[1] AutoLight
GPIO[0] AutoLight
0x44
GpioPolarity
7:0
GPIO[7] Output Polarity
Defines the polarity of the GPO and GPP
pins.
0: Inverted (default)
1: Normal
GPIO[6] Output Polarity
GPIO[5] Output Polarity
GPIO[4] Output Polarity
GPIO[3] Output Polarity
GPIO[2] Output Polarity
GPIO[1] Output Polarity
GPIO[0] Output Polarity
0x45
GpioIntensityOn0
7:0
ON Intensity Index
Defines the ON intensity index
0x00: 0
0x01: 1
0x46
GpioIntensityOn1
0x47
GpioIntensityOn2
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GPIO Parameters
Address Name Bits Description
0x48
GpioIntensityOn3
…
0xFF: 255 (default)
0x49
GpioIntensityOn4
0x4A
GpioIntensityOn5
0x4B
GpioIntensityOn6
0x4C
GpioIntensityOn7
0x4D
GpioIntensityOff0
7:0
OFF Intensity Index
Defines the OFF intensity index
0x00: 0 (default)
0x01: 1
…
0xFF: 255
0x4E
GpioIntensityOff1
0x4F
GpioIntensityOff2
0x50
GpioIntensityOff3
0x51
GpioIntensityOff4
0x52
GpioIntensityOff5
0x53
GpioIntensityOff6
0x54
GpioIntensityOff7
0x56
GpioFunction
7:0
GPIO[7] Function
Defines the intensity index vs PWM pulse
width function.
0: Logarithmic (default)
1: Linear
GPIO[6] Function
GPIO[5] Function
GPIO[4] Function
GPIO[3] Function
GPIO[2] Function
GPIO[1] Function
GPIO[0] Function
0x57
GpioIncFactor
7:0
GPIO[7] Fading Increment Factor
Defines the fading increment f actor .
0: 1, intensity index incremented every
increm ent time (default)
1: 16, intensity index incremented every 16
increm ent times
GPIO[6] Fading Increment Factor
GPIO[5] Fading Increment Factor
GPIO[4] Fading Increment Factor
GPIO[3] Fading Increment Factor
GPIO[2] Fading Increment Factor
GPIO[1] Fading Increment Factor
GPIO[0] Fading Increment Factor
0x58
GpioDecFactor
7:0
GPIO[7] Fading Decrement Factor
Defines the fading decrement factor.
0: 1, intensity index decremented every
decrement time (default)
1: 16, intensity index decremented every 16
decrem ent times
GPIO[6] Fading Decrement Factor
GPIO[5] Fading De crem ent Fa ctor
GPIO[4] Fading Decrement Factor
GPIO[3] Fading Decrement Factor
GPIO[2] Fading Decrement Factor
GPIO[1] Fading Decrement Factor
GPIO[0] Fading Decrement Factor
0x59
GpioIncTime7_6
7:4
GPIO[7] Fading Incr ement Time
Defines the fading increment time.
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GPIO Parameters
Address Name Bits Description
3:0
GPIO[6] Fading Increment Time
0x0: OFF (default)
0x1: 0.5ms
0x2: 1ms
…
0xF: 7.5ms
The total fading in time will be:
GpioIncTime*GpioIncFactor*
(GpioIntensityOn – GpioIntensityOff)
0x5A
GpioIncTime5_4
7:4
GPIO[5] Fading Increment Time
3:0
GPIO[4] Fading Increment Time
0x5B
GpioIncTime3_2
7:4
GPIO[3] Fading Increment Time
3:0
GPIO[2] Fading Increment Time
0x5C
GpioIncTime1_0
7:4
GPIO[1] Fading Increment Time
3:0
GPIO[0] Fading Increment Time
0x5D
GpioDecTime7_6
7:4
GPIO[7] Fading Decrement Time
Defines the fading decrement time.
0x0: OFF
0x1: 0.5ms
0x2: 1ms
…
0x4: 2.0ms (default)
…
0xF: 7.5ms
The total fading out time will be:
GpioDecTime*GpioDecFactor*
(GpioIntensityOn – GpioIntensityOff)
3:0
GPIO[6] Fading Decrement Time
0x5E
GpioDecTime5_4
7:4
GPIO[5] Fading Decrement Time
3:0
GPIO[4] Fading Decrement Time
0x5F
GpioDecTime3_2
7:4
GPIO[3] Fading Decrement Time
3:0
GPIO[2] Fading Decrement Time
0x60
GpioDecTime1_0
7:4
GPIO[1] Fading Decrement Time
3:0
GPIO[0] Fading Decrement Time
0x61
GpioOffDelay7_6
7:4
GPIO[7] OFF Delay
Defines the delay after GPO OFF trigger
before fading out starts.
0x0: OFF (default)
0x1: 200ms
0x2: 400ms
…
0xF: 3000ms
3:0
GPIO[6] OFF Delay
0x62
GpioOffDelay5_4
7:4
GPIO[5] OFF Delay
3:0
GPIO[4] OFF Delay
0x63
GpioOffDelay3_2
7:4
GPIO[3] OFF Delay
3:0
GPIO[2] OFF Delay
0x64
GpioOffDelay1_0
7:4
GPIO[1] OFF Delay
3:0
GPIO[0] OFF Delay
0x65
GpioPullUpDown7_4
7:6
GPIO[7] Pullup/down
Enables pullup/down resistors for GPI pins.
00 : None (default)
01 : Pullup
10 : Pulldown
11 : Reserved
5:4
GPIO[6] Pullup/down
3:2
GPIO[5] Pullup/down
1:0
GPIO[4] Pullup/down
0x66
GpioPullUpDown3_0
7:6
GPIO[3] Pullup/down
5:4
GPIO[2] Pullup/down
3:2
GPIO[1] Pullup/down
1:0
GPIO[0] Pullup/down
0x67
GpioInterrupt7_4
7:6
GPI[7] Interrupt
Defines the GPI edge which will trigger INTB
falling edge and exit Sleep/Doze modes if
relevant.
00 : None (default)
01 : Rising
10 : Falling
11 : Both
5:4
GPI[6] Interrupt
3:2
GPI[5] Interrupt
1:0
GPI[4] Interrupt
0x68
GpioInterrupt3_0
7:6
GPI[3] Interrupt
5:4
GPI[2] Interrupt
3:2
GPI[1] Interrupt
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GPIO Parameters
Address Name Bits Description
1:0
GPI[0] Interrupt
0x69
GpioDebounce
7:0
GPI[7] Debounce
Enables the GPI debounce (done on 10
consecutiv e sample s at 1ms).
0 : OFF (default)
1 : ON
GPI[6] Debounce
GPI[5] Debounce
GPI[4] Debounce
GPI[3] Debounce
GPI[2] Debounce
GPI[1] Debounce
GPI[0] Debounce
Table 22 GPIO Parameters
Table 23 resumes the applicable SPM and I2C parameters for each GPIO mode.
GPI
GPP
GPO
SPM
GpioMode
X
X
X
GpioOutPwrUp
X1
X2
GpioAutoligth
X
GpioPolarity
X
X
GpioIntensityOn
X1
X
GpioIntensityOff
X1
X
GpioFunction
X
X
GpioIncFactor
X
GpioDecFactor
X
GpioIncTime
X
GpioDecTime
X
GpioOffDelay
X
GpioPullUpDown
X
GpioInterrupt
X
GpioDebounce
X
I2C
IrqSrc[4]
X
GpiStat
X
GpoCtrl
X3
GppPinId
X
GppIntensity
X1
1 At power up, GppIntensity of each GPP pin is initialized with GpioIntensityOn or GpioIntensityOff depending on GpioOutPwrUp
corresponding bits value.
2 Only if Autolight is OFF, e lse must be left to 0 (default value)
3 Only if Autolight is OFF, else ignored
Table 23 Applicable SPM/I2C Parameters vs. GPIO Mode
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6 I2C INTERFACE
The I2C implemented on the SX8634 is compliant with:
- standard (100kb/s), fast mode (400kb/s)
- slave mode
- 7 bit address (default 0x2B). The default address can be changed in the NVM at address 0x04.
The host can use the I2C to read and write data at any time. The effective changes will be applied at the next
processing phase (section 3.3).
Three types of registers are considered:
- status ( read). Thes e register s give information about the s tatus of the capaciti ve buttons , slider, GPIs , operation
modes etc…
- control (read/write). These registers control the soft reset, operating modes, GPIOs and offset compensation.
- SPM gateway (read/write). These registers are used for the communication between host and the SPM. The
SPM gateway communication is done typically at power up and is not supposed to be changed when the
application is running. The SPM needs to be re-stored each time the SX8634 is powered down.
The SPM c an be stored pe rmanentl y in the NVM m emory of the SX8634. The SPM gate way comm unication over
the I2C at power up is then not required.
The I2C will be able to read and write from a start address and then perform read or writes sequentially, and the
address increments automatically.
The supported I2C access formats are described in the next sections.
6.1 I2C Write
The format of the I2C write is given in Figure 52.
After the start condition [S], the slave address (SA) is sent, followed by an eighth bit (‘0’) indicating a W rite. The
SX8634 the n Acknowledge s [A] that it is being a ddressed, and the M aster sends an 8 bit D ata Byte consist ing of
the SX8634 Regis ter Ad dre s s (RA) . T he Sla ve Acknowled ges [ A] a nd t he master sends th e a ppr opriate 8 bit Data
Byte (W D0). Again the Slave Ack nowledges [A]. In c ase the m aster needs to write m ore data, a succeedin g 8 bit
Data Byte will follow (WD1), acknowledged by the slave [A]. This sequence will be repeated until the master
terminates the transfer with the Stop condition [P].
SSA 0 RA
A A WD0 A WD1 A WDn A P
optional optional
S: Start condition
SA: Slave Address
A: Acknowledge
RA: Register Address
WDn: Write Data byte (0...n)
P: Stop condition
from master to slave
from slave to master
Figure 52 I2C write
The regis ter addres s is incr emented aut omaticall y when s uccessive re gister data (W D1...W Dn) is suppl ied by th e
master.
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6.2 I2C read
The format of the I2C read is given in Figure 53.
After the start condition [S], the slave address (SA) is sent, followed by an eighth bit (‘0’) indicating a Write. The
SX8634 t hen Ack nowledges [A] that i t is be ing addres sed, a nd the M aster respo nds with an 8 bit Data consisting
of the Register Address (RA). The Slave Acknowledges [A] and the master sends the Repeated Start Condition
[Sr]. Once again, the slave address (SA) is sent, followed by an eighth bit (‘1’) indicating a Read.
The SX8634 resp onds with an Ack nowledge [A] and the read Dat a byte (RD0). If the master needs to read m ore
data it will acknowledge [A] and the SX8634 will send the next read byte (RD1). T his sequence can be rep eated
until the master terminates with a NACK [N] followed by a stop [P].
S SA 0 RA
A A Sr N
S: Start condition
SA: Slave Address
Sr: Repeated Start condition
A: Acknowledge
N: Not Acknowledge (terminating read stream)
RA: Register Address
RDn: Read Data byte (0...n)
P: Stop condition
from master to slave
from slave to master
RD0 A
optional
SA 1 A RD1
optional
RDnA P
Figure 53 I 2C r ead
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6.3 I2C Registers Overview
Address Name R/W Description
0x00 IrqSrc read Interrupt Source
0x01 CapStatMsb read Slider/Button Status MSB
0x02 CapStatLsb read Button Status LSB
0x03 SldPosMsb read Slider Position MSB
0x04 SldPosLsb read Slider Position LSB
0x05 Reserved
0x06 Reserved
0x07 GpiStat read GPI Status
0x08 SpmStat read SPM Status
0x09 CompOpMode read/write
Compensation and
Operating Mode
0x0A GpoCtrl read/write GPO Control
0x0B GppPinId read/write GPP Pin Selection
0x0C GppIntensity read/write GPP Intensity
0x0D SpmCfg read/write SPM Configuration
0x0E SpmBaseAddr read/write SPM Base Address
0x0F Reserved
0xAC SpmKeyMsb read/write SPM Key MSB
0xAD SpmkeyLsb read/write SPM Key LSB
0xB1 SoftReset read/write Software Reset
Table 24 I2 C Re gis ters Overview
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6.4 Status Registers
Address Name Bits Description
0x00 IrqSrc
7 Reserved
Interrupt source flags
0: Inactive (default)
1: Active
INTB goes low if any of
these bits is set.
More than one bit can be
set.
Reading IrqSrc clears it
together with INTB.
6 NVM burn interrupt flag
5
SPM write interrupt flag
4 GPI interrupt flag
3 Slider interrupt flag
2 Buttons interrupt flag
1 Compensation interrupt flag
0 Operating Mode interrupt flag
Table 25 Int er rupt Source
The delay between the actual event and the flags indicating the interrupt source may be one scan period.
IrqSrc[6] is set once NVM burn procedure is completed.
IrqSrc[5] is set once SPM write is effective.
IrqSrc[4] is set if a GPI edge as programmed in GpioInterrupt occurred. GpiStat shows the detailed status of the
GPI pins.
IrqSrc[3] is s et if a Slider event occurr ed (touc h, r elea se, m ove h igh, m ove lo w or position cha nge) . C ap StatMsb,
SldPosMsb and SldPosLsb show the detailed status of the Slider.
IrqSrc[2] is set if a Button event occurred (touch or release if enabled). CapStatMsb and CapStatLsb show the
detailed status of the Buttons.
IrqSrc[1] is set once compensation procedure is completed either through automatic trigger or via host request.
IrqSrc[0] is set when actually e ntering Active or Doze mode either throu gh automatic wak eup or via host request .
CompOpmode shows the current operation mode.
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Address Name Bits Description
0x01 CapStatMsb
7
Reserved
6 Slider Move High Slider Move status
0: No move (default)
1: Move
The status remains high as long as the slider is
touched and no opposite move has occurred.
5 Slider Move Low
4 Slider Touched
Slider Touch status
0: Released (default)
1: Touched
3 Button 11 Touched
Button Touch statu s
0: Released (default)
1: Touched
2 Button 10 Touched
1 Button 9 Touched
0 Button 8 Touched
0x02 CapStatLsb
7 Button 7 Touched
6 Button 6 Touched
5 Button 5 Touched
4 Button 4 Touched
3 Button 3 Touched
2 Button 2 Touched
1 Button 1 Touched
0 Button 0 Touched
Table 26 Slider, Butt on s t atus MSB/LSB
Address Name Bits Description
0x03
SldPosMsb
7:0
Slider Position[15:8]
Shows the current (touched) or last (released)
slider position[15:0] unsigned (default 0x00)
0x04
SldPosLsb
7:0
Slider Position[7:0]
Table 27 Slider position MSB/LSB
Address Name Bits Description
0x07 GpiStat 7:0 GPI[7:0]
Status
Status of each individual GPI pin
0: Low
1: High
Bits of non-GPI pins are set to 0.
Table 28 I2C GPI status
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Address Name Bits Description
0x08 SpmStat
7:4 reserved
3 NvmValid
Indicates if the current NVM is valid.
0: No – QSM is used
1: Yes – NVM is used
2:0 NvmCount
Indicates the number of times NVM has been burned:
0: None – QSM is used (default)
1: Once – NVM is used if NvmValid = 1, else QSM.
2: Twice – NVM is used if NvmValid = 1, else QSM.
3: Three times – NVM is used if NvmValid = 1, else QSM.
4: More than three times – QSM is used
Table 29 I2C SPM status
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6.5 Control Registers
Address Name Bits Description
0x09 CompOpMode
7:3
Reserved*, write only ‘00000’
2 Compensation Indicate s/tr i gger s com pen sati o n pro cedur e
0: Compensation completed (default)
1: read -> compensation running ; write -> trigger
compensation
1:0 Operating Mode
Indicates/programs** operating mode
00: Active mode (default)
01: Doze mode
10: Sleep mode
11: Reserved
Table 30 I2C compensation, operation modes
* The reading of these reserved bits will return varying values.
** After the operating mode change (Active/Doze) the host should wait for INTB or 300ms before
performing any I2C read access.
Address Name Bits Description
0x0A GpoCtrl 7:0 GpoCtrl[7:0]
Triggers ON/OFF state of GPOs when Autolight is
OFF
0: OFF (ie go to IntensityOff)
1: ON (ie go to IntensityOn)
Default is set by SPM parameter GpioOutPwrUp
Bits of non-GPO pins are ignor ed.
Table 31 I2C GPO Control
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Address Name Bits Description
0x0B GppPinId
7:3 Reserved, write only ‘00000’
2:0 GPP Pin Identifier
Defines the GPP pin to which the GppIntensity is
assigned for the following read/write operations
0x0 = GPP0 (default)
0x1 = GPP1
...
0x7 = GPP7
GPPx refers to pin GPIOx configured as GPP
Table 32 I2C GPP Pin Identifier
Address Name Bits Description
0x0C GppIntensity 7:0
Defines the intensity index of the GPP pin selected in GppPinId
0x00: 0
0x01: 1
…
0xFF: 255
Reading returns the intensity index of the GPP pin selected in GppPinId.
Default value is IntensityOn or IntensityOff depending on GpioOutPwrUp.
Table 33 I2C GPP Intensity
Address Name Bits Description
0xB1 SoftReset 7:0 Writing 0xDE followed by 0x00 will reset the chip.
Table 34 I2C Soft Reset
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6.6 SPM Gateway Registers
The SX8634 I 2C int erf ac e offers two registers for exchanging the SPM data with the host.
• SpmCfg
• SpmBaseAddr
Address Name Bits Description
0x0D SpmCfg
7:6 00: Reserved
5:4
Enables I2C SPM mode
00: OFF (default)
01: ON
10: Reserved
11: Reserved
3
Defines r/w direction of SPM
0: SPM write access (default)
1: SPM read access
2:0 000: Reserved
Table 35 SPM access configuration
Address Name Bits Description
0x0E SpmBaseAddr 7:0 SPM Base Address (modulo 8).
The lowest address is 0x00 (default).
The highest address is 0x78.
Table 36 SP M Base Ad dre s s
The exchange of data, read and write, between the host and the SPM is always done in bursts of eight bytes.
The base address of each burst of eight bytes is a modulo 8 number, starting at 0x00 and ending at 0x78.
The registers SpmKeyMsb and SpmKeyLsb are required for NVM programming as described in section 6.7.
Address Name Bits Description
0xAC SpmKeyMsb 7:0 SPM to NVM burn Key MSB Unlock requires writing data: 0x62
Table 37 SPM Key MSB
Address Name Bits Description
0xAD SpmKeyLsb 7:0 SPM to NVM burn Key LSB Unlock requires writing data: 0x9D
Table 38 SPM Key LSB
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6.6.1 SPM Write Sequence
The SPM write can be done in any mode (Active, Doze, Sleep). Writing the SPM in Sleep is useful to avoid
potential transient behaviors.
The SPM must always be written in blocks of 8 bytes. The sequence is described below:
1. Set the I2C in SPM mode by writing “01” to SpmCfg[5:4] and SPM write access by writing ‘0’ to SpmCfg[3].
2. Write the SPM base address to SpmBaseAddr (The base address needs to be a value modulo 8).
3. Write the eight consecutive bytes to I2C address 0, 1, 2, …7
4. Terminate by writing “000” to SpmCfg[5:3].
SSA 00x0D
A0x10
AP
A
S : Start condition
SA : Slave address
A : Slave acknowledge
BA : NVM Base Address
WDn : Write Data byte n, n = 0 to 7
P : Stop condition
...
From master to slave
From slave to master
SSA 0 0x0EA BAA P
A
SSA 00x00
AWD0
AP
A
WD7
SSA 00x0D
A0x00A P
A
1)
2)
3)
4)
Figure 54: SPM Write Sequence
The complete SPM can be written by repeating 16 times the cycles shown in Figure 54 using base addresses
0x00, 0x08, 0x10, …, 0x70, 0x78. Between each sequence the host should wait for INT B (Active/Doze) or 30ms
in Sleep.
In Active or Doze mode, once the SPM write sequence is actually applied, the INTB pin will be asserted and
IrqSrc[5] set. In Sleep mode the SPM write can be actually applied with a delay of 30ms.
The host clears the interrupt and IrqSrc[5] by reading the IrqSrc register.
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6.6.2 SPM Read Sequence
The SPM read can be done in any mode (Active, Doze, Sleep).
The SPM must always be read in blocks of 8 bytes. The sequence is described below:
1. Set the I2C in SPM mode by writing “01” to SpmCfg[5:4] and SPM read access by writing ‘1’ to SpmCfg[3].
2. Write the SPM base address to SpmBaseAddr (The base address needs to be a value modulo 8).
3. Read the eight consecutive bytes from I2C address 0, 1, 2, …7
4. Terminate by writing “000” to SpmCfg[5:3].
S SA 0 0x0D
A0x18
AP
A
S, Sr : Start condition
SA : Slave address
A : Slave acknowledge
N : Not Acknowledge (terminates read stream)
BA : NVM Base Address
RDn : Read Data byte n, n = 0 to 7
P : Stop condition
From master to slave
From slave to master
S SA 0 0x0E
A BA
AP
A
S SA 0 0x0D
A0x00A P
A
S
SA
SSA 0 A0x00 ASr SA 1 A RD0 A
...
RD7 NP
1)
2)
3)
4)
Figure 55: SPM Read Sequenc e
The com plete SPM c an be read b y repeating 1 6 tim es the c ycles sho wn in Figure 55 usin g base addresses 0x00,
0x08, 0x10, …, 0x70, 0x78.
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6.7 NVM burn
The content of the SPM can be copied permanently (burned) into the NVM to be used as the new default
parameters. The burning of the NVM can be done up to three times and must be done only when the SPM is
complete l y written with the des ired dat a. The NVM burn must be done in Active or Doze mode.
Once the NVM burn process is terminated IrqSrc[6] will be set and INTB asserted.
After a reset the burned NVM parameters will be copied into the SPM.
The number of times the NVM has been burned can be monitored by reading NvmCount from the I2C register
SpmStat[2:0].
NVM
SPM
SpmStat[2:0] 1 2 3
0 4
QSM
Figure 56 Simplified Diagram NvmCount
Figure 56 shows the simplified diagram of the NVM counter. The SX8634 is delivered with empty NVM and
NvmCount set to zero. The SPM points to the QSM.
Each NVM burn will increase the NvmCount. At the fourth NVM burn the SX8634 switches definitely to the QSM.
The burning of the SPM into the NVM is done by executing a special sequence of four I2C commands.
1. Write the data 0x62 to the I2C register I2CKeyMsb. Terminate the I2C write by a STOP.
2. Write the data 0x9D to the I2C register I2CKeyLsb. Terminate the I2C write by a STOP.
3. Write the data 0xA5 to the I2C register I2CSpmBaseAddr. Terminate the I2C write by a STOP.
4. Write the data 0x5A to the I2C register I2CSpmBaseAddr. Terminate the I2C write by a STOP.
This is illustrated in Figure 57.
S SA 0 0x0E
A0xA5A P
A
S : Start condition
SA : Slave address
A : Slave acknowledge
P : Stop condition
From master to slave
From slave to master
S SA 0 0x0E
A 0x5A
AP
A
3)
4)
S SA 0 0xAC
A0x62A P
A
SSA 0 0xADA 0x9D
AP
A
1)
2)
Figure 57: NVM burn procedure
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6.8 Monitor Mode
Monitor mode allows the host to read “real-time” sensor information (CAPxRaw, CAPxAvg, CAPxDiff).
It is enabled by setting bit 2 of I2C register SpmCfg (address 0x0D).
W hen enabled, it uses a specific m onitor scan period (Cf below) and generates an interrupt e ver y tim e a new full
set of data is available (hence every scan period).
Address
Name
Bits
Description
0xF9
MonitorScanPeriod
7:0
Monitor Mode Scan Period
0x00: Reserved
0x01: 15ms
…
0x0D: 195ms (default)
…
0xFF: 255 x 15ms
Monitor mode scan period is located at address 0xF9 can be written similarly as SPM data (Cf. 6.6.1)
Interrupt is cleared normally by reading I2C register IrqSrc (address 0x00) but no specific flag is set.
CAPxRaw/Avg/Diff data can be read similarly as SPM data (Cf. 6.6.2)
Base address BA = 0xB4 is the beginning of the CAPxDiff data location and data are organized this way:
0xB4: CAP0Diff, MSB
0xB5: CAP0Diff, LSB
0xB6: CAP1Diff, MSB
etc...
Values are coded 16bits signed 2's complement format and updated at each scan period.
Base address BA = 0x80 is the beginning of the CAPxRaw data location .
Base address BA = 0x9A is the beginning of the CAPxAvg dat a locat ion.
Data should be read before the next interrupt occurs (i.e. within one scan period).
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7 APPLICATION INFORMATION
7.1 Typical Application Schematic
proximity
SX8634
cap2
cap3
cap4
cap5
cap6
cap8
cap7
cap9
gnd
gpio5
gpio4
gpio3
gpio2
gpio1
gnd
gpio0
cap1
cap0
vana
resetb
gnd
gpio7
vdig
gpio6
cap10
cap11
cn
cp
vdd
scl
intb
sda
analog
sensor
interface
micro
processor
RAM
ROM
NVM
I2C
GPIO
controller
power management
clock
generation
RC
PWM
LED
controller
bottom plate
HOST
d1
d0
d2
d3
d4
d5
d6
d7
d0
d1
d2
d3
d4
d5
d6
d7
Figure 58 Ty p ic al Application
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7.2 Example of Touch+Proximity Module
7.2.1 Overview
To demonstrate the proximity sensing feature of the SX863x family, a module has been designed and is illustrated
in figure below.
Touch Buttons
(1.5cm pitch) Proximity Sensor
Module Size (white area) :
sensors area + SX8633 + connector (min.) Bicolor LEDs
(blue, orange) Overlay
(2mm acrylic glass)
Figure 59 Touch+Proximity Module Overview
The touch button controller is running in stand-alone (ie without host) and uses the Autolight mode to turn LEDs
ON/OFF accordingly to the touch buttons and proximity sensing status.
7.2.2 Operation
Module operation can be seen as 5 steps which are described in figure below
1. No finger
=> No proximity detected
=> All LEDs OFF
2. Finger approaches
=> Proximity detect ed
=> Blue LEDs turned ON
3. Button touch
=> Orange LED turned ON
(blue+orange = pink)
4. Button release
=> Or
ange LED turned
OFF
5. Finger removed
=> No proximity detected
=> Blue LEDs turned OFF
Figure 60 Touch+Proximity Module Oper ation
Notes:
- For better user experience, bicolor LEDs have been used here but one could decide to design a module with
normal unicolor LEDs. In this case, step 3 above would simply consist in a higher (blue) intensity for the LED of
the button touched.
- For obvious demonstration purposes the overlay used here is transparent but in typical applications (TV,
Monitor, Set-top box, etc) the overlay would be opaque enough so that when LEDs are OFF (ie no proximity
detected) the PCB is not visible to the user.
7.2.3 Performance
The proximity sensing distance of detection has been measured in these conditions:
- CapProxEnable = ON
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- CapSensitivity = 7 (Max)
- CapThr es hold = 300
- Board main supplied and placed vertically ie same orientation as hand/finger
- Finger pointing center button
The results obtained are provided in table below:
Distance of Detection
Palm
~10cm
Finger (natural position)
~6cm
Orthogonal finger (worst case)
~4cm
Table 39 Proximity Sensing Distance of Detection
7.2.4 Schematics
Figure 61 Touch+Proximity Module Schemat ics
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7.2.5 Layout
Figure 62 Touch+Proximity Module Layout - Top
Figure 63 Touch+Proximity Module Layout - Mid1
Figure 64 Touch+Proximity Module Layout - Mid2
Figure 65 Touch+Proximity Module Layout - Bottom
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8 REFERENCES
[1] Capacitive Touch Sensing Layout guidelines on www.semtech.com
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9 PACKAGING INFORMATION
9.1 Packag e Ou tl in e Dra wing
SX8634 is ass embled in a MLPQ-W32 package as shown in Figure 66.
Figure 66 Package O utline Drawing
9.2 Land Pattern
The land pattern of MLPQ-W32 package, 5 mm x 5 mm is shown in Figure 67.
Figure 67 Land Pattern
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Contact Inf ormation
© Semtech 2010
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