© Semiconductor Components Industries, LLC, 2017
March, 2019 − Rev. 1
1Publication Order Number:
SPSXM002/D
SPSXM002PET
Smart Passive Sensort for
Direct Moisture Sensing
Description
The SPSXM002PET is a battery−free wireless sensor for moisture
level detection on non−metal surfaces. Smart Passive Sensors use the
Magnus−S2® Sensor IC from RF Micron, a UHF RFID chip that is
powered by RF energy harvesting from the UHF reader. The
Magnus−S2 utilizes the patented self−tuning Chameleont engine that
adapts the RF front−end to optimize performance in various
environmental conditions. Changes in antenna detuning due to
moisture contact are digitized by the sensor which can then be read by
a standard EPC Gen 2 compliant reader. These sensor tags function in
either the FCC defined UHF band or the ETSI UHF band.
The small form factor and battery−free capabilities of Smart Passive
Sensors allow them to be designed into applications where size and
accessibility are at a premium.
Features
•Single IC, Smart Passive Sensing
•Small Form Factor Packages
•Direct Moisture Contact Sensing
•On−chip RSSI Sensor
•64 bit TID and 128 bit EPC + 144 Bit User Defined Memory
•EPC Class 1 Gen 2 v.2.0.0 ISO 18 000−6C Compliant
•These Devices are Pb−Free, Halogen Free/BFR Free and are RoHS
Compliant
Applications
•Medical
•Industrial
•Facilities Management
MAXIMUM RATINGS (TA = 25°C unless otherwise noted)
Rating Symbol Max Unit
Human Body Model (Note 1) ESD ±1 kV
Stresses exceeding those listed in the Maximum Ratings table may damage the
device. If any of these limits are exceeded, device functionality should not be
assumed, damage may occur and reliability may be affected.
1. Non−repetitive current pulse at TA = 25°C, per JS−001 waveform.
THERMAL CHARACTERISTICS
Characteristic Symbol Max Unit
Operating and Storage Temperature
Range (Note 2)
TOP
, Tstg −20 to +85 °C
2. Shelf Life − minimum 2 years from date of manufacturing.
www.onsemi.com
RF TAG 101.60x31.75MM
CASE 888AD/AE
See detailed ordering and shipping information on page 5 of
this data sheet.
ORDERING INFORMATION
SPSXM002PET
www.onsemi.com
2
Table 1. ELECTRICAL CHARACTERISTICS (TA = 25°C unless otherwise noted)
Parameter Min Typ Max Units
Operating Frequency (Note 3) FCC 902 928 MHz
ETSI 866 868 MHz
Read Sensitivity (Note 4) −16 dBm
Sensor Code 0 31 codes
RSSI Code 0 31 codes
TID 64 bits
EPC (Note 5) 128 bits
User Memory 144 bits
Product parametric performance is indicated in the Electrical Characteristics for the listed test conditions, unless otherwise noted. Product
performance may not be indicated by the Electrical Characteristics if operated under different conditions.
3. Band specific part numbers can be found in the ordering information table
4. Measured in free space, anechoic chamber with a linearly polarized antenna at 50 cm read distance
5. User Memory can be configured to be an EPC extension, effectively making a 272 bit EPC code
Figure 1. Moisture Contact Test Area
Moisture Sensing
The SPSXM002 generates sensor codes from 0 to 31, with
a free space sensor code average of 18. Figure 1 shows the
moisture sensitive portion of the tag used to collect the data
in Figure 2. The SPSXM002 with a damp cloth over the
sensor yields a sensor value 5 codes lower than the dry test.
For the moisture test seen in Figure 1, the sensor value shifts
approximately 5 codes when water is detected on the surface
of the tag. Due to the Smart Passive Sensors’ self−tuning
capability, the sensor code does shift over frequency as it
tunes itself to maximize reflected power to the reader. This
makes it important to account for the frequency at which the
sensor was read. This factor must be accounted for in the
reader software in order to ensure reliable wet vs. dry reads.
For more information on how Smart Passive Sensors
generate sensor codes, please refer to Application Note
AND9209/D.
Figure 2. Sensor Code for Wet and Dry Conditions
DRY
WET
SPSXM002PET
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3
Table 2. MEMORY MAP
Bank # Bank Name R/W Bit Address Description LSB MSB Default Value
11 USER
N/A A0−AF On−chip RSSI Threshold N/A
READ/WRITE
80−8F User Memory 0
70−7F User Memory 0
60−6F User Memory 0
50−5F User Memory 0
40−4F User Memory 0
30−3F User Memory 0
20−2F User Memory 0
10−1F User Memory 0
00−0F User Memory 0
10 TID READ ONLY
50−5F TID[15:0]
40−4F TID[31:16]
30−3F TID[47:32]
20−2F Extended TID Header
10−1F Tag Model Number
08−13 Manufacturer ID
00−07 Class ID
01 EPC
WRITE ONLY 140−14F EPC Configure 0
READ/WRITE
90−9F EPC#[15:0] 0
80−8F EPC#[31:16] 0
70−7F EPC#[47:32] 0
60−6F EPC#[63:48] 0
50−5F EPC#[79:64] 0
40−4F EPC#[95:80] 0
30−3F EPC#[111:96] 0
20−2F EPC#[127:112] 0
10−1F StoredPC[15:0] 0
READ ONLY 00−0F StoredCRC[15:0] 0
00 RESERVED
READ/WRITE F0−FF Sensor Overwrite 0
READ ONLY
D0−DF On−chip RSSI Code N/A
B0−BF Sensor Code N/A
READ/WRITE
50−5F Analog Overwrite 0
30−3F Access Password[15:0] 0
20−2F Access Password[31:16] 0
10−1F Kill Password[15:0] 0
00−0F Kill Password[31:16] 0
SPSXM002PET
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4
Tag Memory
Memory Configuration
Memory is organized according to the EPCglobal
Generation−2 UHF RFID specification. There are two
possible configurations for the EPC ID:
•8−word EPC code and 9 free words in the USER
memory bank, as shown in the Memory Map
•17−word EPC code and no free USER memory (EPC
lengths above 11 words may not be supported on all
readers.)
The 8−word configuration is the default. To change to the
17−word configuration, write 0001h to the EPC Bank, word
address 14h. The memory can be reset to the default 8−word
EPC configuration by writing 0000h to the same location.
This EPC configuration can be configured and reconfigured
repeatedly as long as the EPC memory bank is not
permanently locked by a LOCK command. Once the EPC
memory bank is permanently locked, it cannot be
reconfigured.
Reserved Memory − Passwords
Reserved Memory contains the ACCESS and KILL
passwords. There is a 32−bit Access Password and a 32−bit
Kill Password. The default for both Kill and Access
Passwords is 0000h.
Access Password
The Access Password is a 32−bit value stored in Reserved
Memory 20h to 3Fh MSB first. The default value is all
zeroes. Tags with a non−zero Access Password will require
a reader to issue this password before transitioning to the
secured state.
Kill Password
The Kill Password is a 32−bit value stored in Reserve
Memory 00h to 1Fh, MSB first. The default value is all
zeroes. A reader shall use a tag’s kill password once to kill
the tag and render it silent thereafter. A tag will not execute
a kill operation if its Kill Password is all zeroes.
EPC Memory − EPC data, Protocol Control Bits, and
CRC16
As required by the Gen−2 specification, EPC memory
contains a 16−bit cyclic−redundancy check word
(StoredCRC) at memory addresses 00h to 0Fh, the 16
protocol−control bits (StoredPC) at memory addresses 10h
to 1Fh, and an EPC value beginning at address 20h.
The protocol control fields include a five−bit EPC length,
a one−bit user−memory indicator (UMI), a one−bit extended
protocol control indicator, and a nine−bit numbering system
identifier (NSI).
On power−up, the IC calculates the StoredCRC over the
stored PC bits and the EPC specified by the EPC length field
in the StoredPC. For more details about the StoredPC field
or the StoredCRC, please see the Gen 2 specification.
The StoredCRC, StoredPC, and EPC are stored MSB first
(i.e. the EPC’s MSB is stored in location 20h).
Tag Identification (TID) Memory
The read−only Tag Identification memory contains the
manufacturer−specific data. The manufacturer Mask
Designer ID (MDID) is 824h (bits 08h to 13h). The logic 1
in the most significant bit of the MDID indicates the
presence of an extended TID consisting of a 16−bit header
and a 48−bit serialization. The Magnus−S2 model number is
in bits 10h to 1Fh and the EPCglobal® Class ID (E2h) is in
00h to 07h.
Sensor Functions
Accessing the Sensor Code
The Magnus−S2 Chameleon engine stores tuning
information in a user−accessible memory register. The
“Sensor Code” register (B0h−BFh in the Reserved memory
bank) contains the current setting and controls the tuning
capacitors that are used to adjust the input impedance.
To get the results of the self−tuning operation, a READ
command may be issued for the Sensor Code (B0h −BFh in
the Reserved memory bank). Because the tuning network
offers 32 different levels of impedance, only the 5 least
significant bits (BBh −BFh) in the register are actually
implemented and used. (The 32 levels represent increasing
amounts of capacitance added to the input impedance, with
the lowest capacitance applied at level 0.) Returned results
will be in the form 0000 0000 000x xxxx, where the 5 LSBs
define the current tuning.
For use in sensing applications, the Sensor Code register
can be monitored for changes over time or at different
locations, or it can be checked for changes to a baseline
reading that is taken when the tag is placed into service.
Depending on the needs of the application, the reference or
baseline value(s) may be written back into regular user
memory or may be stored elsewhere on the user’s network.
The SPSXM002 may require more than its minimum
sensitivity power in order to sense values near the ends of the
code range (0−5 and 27−31). The minimum required power
tends to increase gradually as the Sensor Code moves from
5 to 0 or from 27 to 31.
Overriding Default Chameleon Behavior
By default, the Chameleon engine will self−tune when
Magnus−S2 powers up, and the tuning capacitance chosen
will be held constant until the chip powers down. There are
also two additional modes: Chameleon can tune
continuously – not just at power up – and Chameleon can be
forced to a user−chosen setting.
To cause Chameleon to adjust continuously while
Magnus−S2 is powered up, write 0800h to the Analog
SPSXM002PET
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5
Overwrite word (address 50h−5Fh in the Reserved Bank)
using a standard WRITE command.
To force Chameleon to a desired setting, write 4000h to the
Analog Overwrite word, and the tuning value to the Sensor
Overwrite word (address F0h−FFh in the Reserved Bank)
with standard WRITE commands. The tuning value format
is 0000 0000 000x xxxx, where x_xxxx represents the
desired 5−bit tuning. When the above sequence is executed
correctly, the setting x_xxxx will be transferred into the
Sensor Code register and will be held constant until the next
power−up or until the user writes a different value into the
Sensor Overwrite word.
The Analog Overwrite word is non−volatile: values
written will persist through chip power cycles. The Sensor
Overwrite word is volatile: if a fixed Chameleon setting is
desired, it must be re−written every time Magnus−S2 is
powered up.
On−Chip RSSI Code
Magnus−S2 incorporates circuitry that measures
incoming signal strength and converts it to a digital value:
the On−Chip RSSI (Received Signal Strength Indicator)
Code. This can be communicated to a reader and used for
control purposes. The On−Chip RSSI Code has a 32−level
range, represented by a 5−bit number.
The On−Chip RSSI Code, in word D0h−DFh in the
Reserved Bank, will be returned as the 5 LSBs of a response
to a standard READ command specifying word address Dh.
Magnus−S2 must first receive an On−Chip RSSI Request
before the On−Chip RSSI Code becomes available.
On−Chip RSSI Requests
On−Chip RSSI Request is a tool for a reader to specify that
it wants to hear only from tags that are seeing a desired
amount of received signal strength. It allows a reader to limit
its communications only to nearby tags – or conversely, to
“mute” nearby tags in order to attempt communication with
tags receiving weak signals.
The On−Chip RSSI Threshold “address” (A0h of the User
Bank) is used only by Magnus−S2 to interpret a SELECT
command and is not an actual memory location. It is sent by
the reader using a standard Gen 2 SELECT command. The
6−bits of On−Chip RSSI Threshold Value/Control are
communicated as part of the Mask sent to the tags.
The list below from the Gen 2 version 2.0.0 spec shows the
format of a SELECT command. To send an On−Chip RSSI
Request, the reader issues a SELECT command with:
•MemBank set to 3h (11b)
•The On−Chip RSSI Threshold address (A0h) in the
Pointer field
•Length set to 00001000b (the On−Chip RSSI request
value consists of the lower 6 bits of an 8−bit Mask)
•The On−Chip RSSI request in the lower 6 bits of the
Mask, consisting of a leading bit for control followed
by 5 bits for the On−Chip RSSI Code at which the
reader wants to define the tags’ response/no−response
threshold.
The control bit determines whether the threshold value is
interpreted by Magnus−S2 as a lower or upper threshold.
Specifically, if the control bit is set to 0, it will respond if its
internally generated On−Chip RSSI Code is less than or
equal to the threshold value. If the control bit is 1, it will
respond if its On−Chip RSSI Code is greater than the
threshold.
ORDERING INFORMATION
Device UHF Band Attach Material Package Shipping
SPS1M002PET FCC
902−928 MHz
Non−metal Case 888AD 1000 / Reel
SPS2M002PET ETSI
866−868 MHz
Non−metal Case 888AE 1000 / Reel
SPSXM002PET
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6
PACKAGE DIMENSIONS
RF TAG 91.5x26.5mm
CASE 888AD
ISSUE O
DIM
D
MIN
MILLIMETERS
88.90
E23.90
89.10
24.10
MAX
NOTES:
1. DIMENSIONING AND TOLERANCING PER
ASME Y14.5M, 1994.
2. CONTROLLING DIMENSION: MILLIMETERS.
3. ANTENNA SIZE DETERMINED BY DIMENSIONS
D AND E.
4. LABEL SIZE DETERMINED BY DIMENSIONS D1
AND E1.
5. LABEL IS 0.076 THICK PET TAPE. ANTENNA IS
0.009 THICK ALUMINUM.
D
E1
TOP VIEW
D1 90.50
E1 25.50
91.50
26.50
E
D1
RF TAG 101.60x31.75MM
CASE 888AE
ISSUE A
DIM
D
MIN
MILLIMETERS
93.90
E23.90
94.00
24.00
NOM
NOTES:
1. DIMENSIONING AND TOLERANCING PER
ASME Y14.5M, 1994.
2. CONTROLLING DIMENSION: MILLIMETERS.
3. ANTENNA SIZE DETERMINED BY DIMENSIONS
D AND E.
4. LABEL SIZE DETERMINED BY DIMENSIONS D1
AND E1.
5. LABEL IS 0.076 THICK PET TAPE. ANTENNA IS
0.009 THICK ALUMINUM.
D
E1
TOP VIEW
D1 101.10
E1 31.25
101.60
31.75
E
D1
MAX
94.10
24.10
102.10
32.25
PUBLICATION ORDERING INFORMATION
N. American Technical Support: 800−282−9855 Toll Free
USA/Canada
Europe, Middle East and Africa Technical Support:
Phone: 421 33 790 2910
SPSXM002/D
Smart Passive Sensor is a trademark of RFMicron, Inc.
Magnus−S2 is a registered trademark of RFMicron, Inc.
Chameleon is a trademark of RFMicron, Inc.
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