0330.SBO.354 - Bosch Sensortec

BMP280: Data sheet

Document revision

1.12

Document release date

July 11th, 2014

Document number

BST-BMP280-DS001-10

Technical reference code(s)

0 273 300 354

Notes

Data in this document are subject to change without notice. Product

photos and pictures are for illustration purposes only and may differ from

the real product’s appearance.

Data sheet

BMP280

Digital Pressure Sensor

Bosch Sensortec

Datasheet

BMP280 Digital Pressure Sensor

Page 2

BST-BMP280-DS001-10 | Revision 1.12 | July 2014 Bosch Sensortec

third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.

Note: Specifications within this document are subject to change without notice. Not intended for publication.

BMP280

DIGITAL PRESSURE SENSOR

Key parameters

 Pressure range 300 … 1100 hPa

(equiv. to +9000…-500 m above/below sea level)

 Package 8-pin LGA metal-lid

Footprint : 2.0 × 2.5 mm², height: 0.95 mm

 Relative accuracy ±0.12 hPa, equiv. to ±1 m

(950 … 1050hPa @25°C)

 Absolute accuracy typ. ±1 hPa

(950 ...1050 hPa, 0 ...+40 °C)

 Temperature coefficient offset 1.5 Pa/K, equiv. to 12.6 cm/K

(25 ... 40°C @900hPa)

 Digital interfaces I²C (up to 3.4 MHz)

SPI (3 and 4 wire, up to 10 MHz)

 Current consumption 2.7µA @ 1 Hz sampling rate

 Temperature range -40 … +85 °C

 RoHS compliant, halogen-free

 MSL 1

Typical applications

 Enhancement of GPS navigation

(e.g. time-to-first-fix improvement, dead-reckoning, slope detection)

 Indoor navigation (floor detection, elevator detection)

 Outdoor navigation, leisure and sports applications

 Weather forecast

 Health care applications (e.g. spirometry)

 Vertical velocity indication (e.g. rise/sink speed)

Target devices

 Handsets such as mobile phones, tablet PCs, GPS devices

 Navigation systems

 Portable health care devices

 Home weather stations

 Flying toys

 Watches

Datasheet

BMP280 Digital Pressure Sensor

Page 3

BST-BMP280-DS001-10 | Revision 1.12 | July 2014 Bosch Sensortec

third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.

Note: Specifications within this document are subject to change without notice. Not intended for publication.

General Description

Robert Bosch is the world market leader for pressure sensors in automotive and consumer

applications. Bosch’s proprietary APSM (Advanced Porous Silicon Membrane) MEMS

manufacturing process is fully CMOS compatible and allows a hermetic sealing of the cavity in

an all silicon process. The BMP280 is based on Bosch’s proven Piezo-resistive pressure sensor

technology featuring high EMC robustness, high accuracy and linearity and long term stability.

The BMP280 is an absolute barometric pressure sensor especially designed for mobile

applications. The sensor module is housed in an extremely compact 8-pin metal-lid LGA

package with a footprint of only 2.0 × 2.5 mm2 and 0.95 mm package height. Its small

dimensions and its low power consumption of 2.7 µA @1Hz allow the implementation in battery

driven devices such as mobile phones, GPS modules or watches.

As the successor to the widely adopted BMP180, the BMP280 delivers high performance in all

applications that require precise pressure measurement. The BMP280 operates at lower noise,

supports new filter modes and an SPI interface within a footprint 63% smaller than the BMP180.

The emerging applications of in-door navigation, health care as well as GPS refinement require

a high relative accuracy and a low TCO at the same time. BMP180 and BMP280 are perfectly

suitable for applications like floor detection since both sensors feature excellent relative

accuracy is ±0.12 hPa, which is equivalent to ±1 m difference in altitude. The very low offset

temperature coefficient (TCO) of 1.5 Pa/K translates to a temperature drift of only 12.6 cm/K.

Please contact your regional Bosch Sensortec partner for more information about software

packages enhancing the calculation of the altitude given by the BMP280 pressure reading.

Table 1: Comparison between BMP180 and BMP280

Parameter

BMP180

BMP280

Footprint

3.6 × 3.8 mm

2.0 × 2.5 mm

Minimum VDD

1.80 V

1.71 V

Minimum VDDIO

1.62 V

1.20 V

Current consumption @3 Pa RMS noise

12 µA

2.7 µA

RMS Noise

3 Pa

1.3 Pa

Pressure resolution

1 Pa

0.18 Pa

Temperature resolution

0.1°C

0.01°C

Interfaces

I²C

I²C & SPI (3 and 4 wire,

mode ‘00’ and ‘11’)

Measurement modes

Only P or T, forced

P&T, forced or periodic

Measurement rate

up to 120 Hz

up to 157 Hz

Filter options

None

Five bandwidths

Datasheet

BMP280 Digital Pressure Sensor

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BST-BMP280-DS001-10 | Revision 1.12 | July 2014 Bosch Sensortec

third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.

Note: Specifications within this document are subject to change without notice. Not intended for publication.

Index of Contents

1. SPECIFICATION ........................................................................................................................ 7

2. ABSOLUTE MAXIMUM RATINGS ............................................................................................ 9

3. FUNCTIONAL DESCRIPTION ................................................................................................. 10

3.1 BLOCK DIAGRAM ............................................................................................................... 11

3.2 POWER MANAGEMENT ....................................................................................................... 11

3.3 MEASUREMENT FLOW ....................................................................................................... 11

3.3.1 PRESSURE MEASUREMENT ........................................................................................................... 12

3.3.2 TEMPERATURE MEASUREMENT ..................................................................................................... 13

3.3.3 IIR FILTER .................................................................................................................................... 13

3.4 FILTER SELECTION ............................................................................................................ 14

3.5 NOISE .............................................................................................................................. 15

3.6 POWER MODES ................................................................................................................. 15

3.6.1 SLEEP MODE ................................................................................................................................ 16

3.6.2 FORCED MODE ............................................................................................................................. 16

3.6.3 NORMAL MODE ............................................................................................................................. 16

3.6.4 MODE TRANSITION DIAGRAM ......................................................................................................... 17

3.7 CURRENT CONSUMPTION................................................................................................... 18

3.8 MEASUREMENT TIMINGS .................................................................................................... 18

3.8.1 MEASUREMENT TIME .................................................................................................................... 18

3.8.2 MEASUREMENT RATE IN NORMAL MODE ......................................................................................... 19

3.9 DATA READOUT ................................................................................................................ 19

3.10 DATA REGISTER SHADOWING ........................................................................................... 20

3.11 OUTPUT COMPENSATION ................................................................................................. 20

3.11.1 COMPUTATIONAL REQUIREMENTS ............................................................................................... 20

3.11.2 TRIMMING PARAMETER READOUT ................................................................................................ 21

3.11.3 COMPENSATION FORMULA .......................................................................................................... 21

3.12 CALCULATING PRESSURE AND TEMPERATURE ................................................................... 22

4. GLOBAL MEMORY MAP AND REGISTER DESCRIPTION .................................................. 24

4.1 GENERAL REMARKS .......................................................................................................... 24

4.2 MEMORY MAP ................................................................................................................... 24

4.3 REGISTER DESCRIPTION .................................................................................................... 24

4.3.1 REGISTER 0XD0 “ID” .................................................................................................................... 24

4.3.2 REGISTER 0XE0 “RESET” .............................................................................................................. 24

4.3.3 REGISTER 0XF3 “STATUS” ............................................................................................................ 25

4.3.4 REGISTER 0XF4 “CTRL_MEAS” ...................................................................................................... 25

4.3.5 REGISTER 0XF5 “CONFIG” ............................................................................................................ 26

4.3.6 REGISTER 0XF7…0XF9 “PRESS” (_MSB, _LSB, _XLSB) .................................................................. 26

4.3.7 REGISTER 0XFA…0XFC “TEMP” (_MSB, _LSB, _XLSB)................................................................... 27

Datasheet

BMP280 Digital Pressure Sensor

Page 5

BST-BMP280-DS001-10 | Revision 1.12 | July 2014 Bosch Sensortec

third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.

Note: Specifications within this document are subject to change without notice. Not intended for publication.

5. DIGITAL INTERFACES ............................................................................................................ 28

5.1 INTERFACE SELECTION ...................................................................................................... 28

5.2 I²C INTERFACE.................................................................................................................. 28

5.2.1 I²C WRITE .................................................................................................................................... 29

5.2.2 I²C READ ..................................................................................................................................... 29

5.3 SPI INTERFACE ................................................................................................................. 30

5.3.1 SPI WRITE ................................................................................................................................... 31

5.3.2 SPI READ .................................................................................................................................... 31

5.4 INTERFACE PARAMETER SPECIFICATION ............................................................................. 32

5.4.1 GENERAL INTERFACE PARAMETERS ............................................................................................... 32

5.4.2 I²C TIMINGS ................................................................................................................................. 32

5.4.3 SPI TIMINGS ................................................................................................................................ 33

6. PIN-OUT AND CONNECTION DIAGRAM ............................................................................... 35

6.1 PIN-OUT ........................................................................................................................... 35

6.2 CONNECTION DIAGRAM 4-WIRE SPI ................................................................................... 36

6.3 CONNECTION DIAGRAM 3-WIRE SPI ................................................................................... 37

6.4 CONNECTION DIAGRAM I2C ................................................................................................ 38

7. PACKAGE, REEL AND ENVIRONMENT ................................................................................ 39

7.1 OUTLINE DIMENSIONS ....................................................................................................... 39

7.2 LANDING PATTERN RECOMMENDATION ............................................................................... 40

7.3 MARKING .......................................................................................................................... 41

7.3.1 MASS PRODUCTION DEVICES ........................................................................................................ 41

7.3.2 ENGINEERING SAMPLES ................................................................................................................ 41

7.4 SOLDERING GUIDELINES .................................................................................................... 42

7.5 TAPE AND REEL SPECIFICATION ......................................................................................... 43

7.5.1 DIMENSIONS ................................................................................................................................ 43

7.5.2 ORIENTATION WITHIN THE REEL ..................................................................................................... 43

7.6 MOUNTING AND ASSEMBLY RECOMMENDATIONS ................................................................. 44

7.7 ENVIRONMENTAL SAFETY .................................................................................................. 44

7.7.1 ROHS ......................................................................................................................................... 44

7.7.2 HALOGEN CONTENT ..................................................................................................................... 44

7.7.3 INTERNAL PACKAGE STRUCTURE ................................................................................................... 44

8. APPENDIX 1: COMPUTATION FORMULAE FOR 32 BIT SYSTEMS .................................. 44

8.1 COMPENSATION FORMULA IN FLOATING POINT .................................................................... 44

8.2 COMPENSATION FORMULA IN 32 BIT FIXED POINT ................................................................ 45

9. LEGAL DISCLAIMER ............................................................................................................... 47

9.1 ENGINEERING SAMPLES .................................................................................................... 47

Datasheet

BMP280 Digital Pressure Sensor

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BST-BMP280-DS001-10 | Revision 1.12 | July 2014 Bosch Sensortec

third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.

Note: Specifications within this document are subject to change without notice. Not intended for publication.

9.2 PRODUCT USE .................................................................................................................. 47

9.3 APPLICATION EXAMPLES AND HINTS ................................................................................... 47

10. DOCUMENT HISTORY AND MODIFICATION ..................................................................... 48

Datasheet

BMP280 Digital Pressure Sensor

Page 7

BST-BMP280-DS001-10 | Revision 1.12 | July 2014 Bosch Sensortec

third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.

Note: Specifications within this document are subject to change without notice. Not intended for publication.

1. Specification

If not stated otherwise,

 All values are valid over the full voltage range

 All minimum/maximum values are given for the full accuracy temperature range

 Minimum/maximum values of drifts, offsets and temperature coefficients are ±3 values

over lifetime

 Typical values of currents and state machine timings are determined at 25 °C

 Minimum/maximum values of currents are determined using corner lots over complete

temperature range

 Minimum/maximum values of state machine timings are determined using corner lots

over 0…+65 °C temperature range

The specification tables are split into pressure and temperature part of BMP280

Table 2: Parameter specification

Parameter

Symbol

Condition

Min

Typ

Max

Units

Operating temperature

range

operational

-40

+85

°C

full accuracy

+65

Operating pressure

range

full accuracy

300

1100

hPa

Sensor supply voltage

VDD

ripple max. 50mVpp

1.71

1.8

3.6

Interface supply voltage

VDDIO

1.2

1.8

3.6

Supply current

IDD,LP

1 Hz forced mode,

pressure and

temperature, lowest

power

2.8

4.2

µA

Peak current

Ipeak

during pressure

measurement

720

1120

µA

Current at temperature

measurement

IDDT

325

µA

Sleep current1

IDDSL

25 °C

0.1

0.3

µA

Standby current

(inactive period of

normal mode) 2

IDDSB

25 °C

0.2

0.5

µA

Relative accuracy

pressure3

VDD = 3.3V

Arel

700 … 900hPa

25 . . . 40 °C

±0.12

hPa

±1.0

Typical value at VDD = VDDIO = 1.8 V, maximal value at VDD = VDDIO = 3.6 V.

Target values

Datasheet

BMP280 Digital Pressure Sensor

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BST-BMP280-DS001-10 | Revision 1.12 | July 2014 Bosch Sensortec

third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.

Note: Specifications within this document are subject to change without notice. Not intended for publication.

Offset temperature

coefficient3

TCO

900hPa

25 . . . 40 °C

±1.5

Pa/K

12.6

cm/K

Absolute accuracy

pressure

ext

300 . . . 1100 hPa

-20 . . . 0 °C

±1.7

hPa

full

300 . . . 1100 hPa

0 . . . 65 °C

±1.0

hPa

Resolution of

output data in ultra high

resolution mode4

Pressure

0.0016

hPa

Temperature

0.01

°C

Noise in pressure

Vp,full

Full bandwidth, ultra

high resolution

See chapter 3.5

1.3

Vp,filtered

Lowest bandwidth,

ultra high resolution

See chapter 3.5

0.2

1.7

Absolute accuracy

temperature5

@ 25 °C

±0.5

°C

0 . . . +65 °C

±1.0

°C

PSRR (DC)

PSRR

full VDD range

±0.005

Pa/

Long term stability6

Pstab

12 months

±1.0

hPa

Solder drifts



Minimum solder

height 50 µm

-0.5

hPa

Start-up time

tstartup

Time to first

communication after

both VDD > 1.58V and

VDDIO > 0.65V

Possible sampling rate

fsample

osrs_t = osrs_p = 1;

See chapter 3.8

157

182

tbd7

Standby time accuracy

tstandby

±5

±25

Using double precision or 64 bit integer compensation formula, 16×oversampling

Temperature measured by the internal temperature sensor. This temperature value depends on the PCB temperature, sensor

element self-heating and ambient temperature and is typically above ambient temperature.

Long term stability is specified in the full accuracy operating pressure range 0 … 65°C

Depends on application case, please contact Application Engineer for further questions

Datasheet

BMP280 Digital Pressure Sensor

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BST-BMP280-DS001-10 | Revision 1.12 | July 2014 Bosch Sensortec

third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.

Note: Specifications within this document are subject to change without notice. Not intended for publication.

2. Absolute maximum ratings

The absolute maximum ratings are provided in Table 3.

Table 3: Absolute maximum ratings

Parameter

Condition

Min

Max

Unit

Voltage at any supply pin

VDD and VDDIO Pin

-0.3

4.25

Voltage at any interface pin

-0.3

VDDIO + 0.3

Storage Temperature

≤ 65% rel. H.

-45

+85

°C

Pressure

20 000

hPa

ESD

HBM, at any Pin

±2

CDM

±500

Machine model

±200

Datasheet

BMP280 Digital Pressure Sensor

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BST-BMP280-DS001-10 | Revision 1.12 | July 2014 Bosch Sensortec

third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.

Note: Specifications within this document are subject to change without notice. Not intended for publication.

3. Functional description

The BMP280 consists of a Piezo-resistive pressure sensing element and a mixed-signal ASIC.

The ASIC performs A/D conversions and provides the conversion results and sensor specific

compensation data through a digital interface.

BMP280 provides highest flexibility to the designer and can be adapted to the requirements

regarding accuracy, measurement time and power consumption by selecting from a high

number of possible combinations of the sensor settings.

BMP280 can be operated in three power modes (see chapter 3.6):

 sleep mode

 normal mode

 forced mode

In sleep mode, no measurements are performed. Normal mode comprises an automated

perpetual cycling between an active measurement period and an inactive standby period. In

forced mode, a single measurement is performed. When the measurement is finished, the

sensor returns to sleep mode.

A set of oversampling settings is available ranging from ultra low power to ultra high resolution

setting in order to adapt the sensor to the target application. The settings are predefined

combinations of pressure measurement oversampling and temperature measurement

oversampling. Pressure and temperature measurement oversampling can be selected

independently from 0 to 16 times oversampling (see chapter 3.3.1 and 3.3.2):

 Temperature measurement

 Ultra low power

 Low power

 Standard resolution

 High resolution

 Ultra high resolution

BMP280 is equipped with a built-in IIR filter in order to minimize short-term disturbances in the

output data caused by the slamming of a door or window. The filter coefficient ranges from 0

(off) to 16.

In order to simplify the device usage and reduce the high number of possible combinations of

power modes, oversampling rates and filter settings, Bosch Sensortec provides a proven set of

recommendations for common use-cases in smart-phones, mobile weather stations or flying

toys (see chapter 3.4):

 Handheld device low-power (e.g. smart phones running Android)

 Handheld device dynamic (e.g. smart phones running Android)

 Weather monitoring (setting with lowest power consumption)

 Elevator / floor change detection

 Drop detection

 Indoor navigation

Datasheet

BMP280 Digital Pressure Sensor

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BST-BMP280-DS001-10 | Revision 1.12 | July 2014 Bosch Sensortec

third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.

Note: Specifications within this document are subject to change without notice. Not intended for publication.

3.1 Block diagram

Figure 1 shows a simplified block diagram of the BMP280:

Figure 1: Block diagram of BMP280

3.2 Power management

The BMP280 has two separate power supply pins

 VDD is the main power supply for all internal analog and digital functional blocks

 VDDIO is a separate power supply pin, used for the supply of the digital interface

A power-on reset generator is built in which resets the logic circuitry and the register values

after the power-on sequence. There are no limitations on slope and sequence of raising the VDD

and VDDIO levels. After powering up, the sensor settles in sleep mode (see 3.6.1).

Warning. Holding any interface pin (SDI, SDO, SCK or CSB) at a logical high level when VDDIO is

switched off can permanently damage the device due caused by excessive current flow through

the ESD protection diodes.

If VDDIO is supplied, but VDD is not, the interface pins are kept at a high-Z level. The bus can

therefore already be used freely before the BMP280 VDD supply is established.

3.3 Measurement flow

The BMP280 measurement period consists of a temperature and pressure measurement with

selectable oversampling. After the measurement period, the data are passed through an

optional IIR filter, which removes short-term fluctuations in pressure (e.g. caused by slamming a

door). The flow is depicted in the diagram below.

Logic

OSC NVM

ADC

Pressure/

temperature

sensing

element

Voltage

reference

Voltage

regulator

(analog &

digital)

VDDIO

GND

SDI

SDO

SCK

CSB

VDD

POR

Analog

front-end

Datasheet

BMP280 Digital Pressure Sensor

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Measure temperature

(oversampling set by osrs_t;

skip if osrs_t = 0)

Start

measurement cycle

Measure pressure

(oversampling set by osrs_p;

skip if osrs_p = 0)

IIR filter enabled?

End

measurement cycle

IIR filter initialised? Copy ADC values

to filter memory

(initalises IIR filter)

Update filter memory using

filter memory, ADC value

and filter coefficient

Yes

Copy filter memory

to output registers

Figure 2: BMP280 measurement cycle

The individual blocks of the diagram above will be detailed in the following subchapters.

3.3.1 Pressure measurement

Pressure measurement can be enabled or skipped. Skipping the measurement could be useful

if BMP280 is used as temperature sensor. When enabled, several oversampling options exist.

Each oversampling step reduces noise and increases the output resolution by one bit, which is

stored in the XLSB data register 0xF9. Enabling/disabling the measurement and oversampling

settings are selected through the osrs_p[2:0] bits in control register 0xF4.

Table 4: osrs_p settings

Oversampling setting

Pressure

oversampling

Typical pressure

resolution

Recommended

temperature

oversampling

Pressure measurement

skipped

Skipped

(output set to

0x80000)

–

As needed

Ultra low power

×1

16 bit / 2.62 Pa

×1

Low power

×2

17 bit / 1.31 Pa

×1

Standard resolution

×4

18 bit / 0.66 Pa

×1

High resolution

×8

19 bit / 0.33 Pa

×1

Ultra high resolution

×16

20 bit / 0.16 Pa

×2

In order to find a suitable setting for osrs_p, please consult chapter 3.4.

Datasheet

BMP280 Digital Pressure Sensor

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third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.

Note: Specifications within this document are subject to change without notice. Not intended for publication.

3.3.2 Temperature measurement

Temperature measurement can be enabled or skipped. Skipping the measurement could be

useful to measure pressure extremely rapidly. When enabled, several oversampling options

exist. Each oversampling step reduces noise and increases the output resolution by one bit,

which is stored in the XLSB data register 0xFC. Enabling/disabling the temperature

measurement and oversampling setting are selected through the osrs_t[2:0] bits in control

Table 5: osrs_t settings

osrs_t[2:0]

Temperature oversampling

Typical temperature

resolution

000

Skipped

(output set to 0x80000)

–

001

×1

16 bit / 0.0050 °C

010

×2

17 bit / 0.0025 °C

011

×4

18 bit / 0.0012 °C

100

×8

19 bit / 0.0006 °C

101, 110, 111

×16

20 bit / 0.0003 °C

It is recommended to base the value of osrs_t on the selected value of osrs_p as per Table 4.

Temperature oversampling above ×2 is possible, but will not significantly improve the accuracy

of the pressure output any further. The reason for this is that the noise of the compensated

pressure value depends more on the raw pressure than on the raw temperature noise.

Following the recommended setting will result in an optimal noise-to-power ratio.

3.3.3 IIR filter

The environmental pressure is subject to many short-term changes, caused e.g. by slamming of

a door or window, or wind blowing into the sensor. To suppress these disturbances in the output

data without causing additional interface traffic and processor work load, the BMP280 features

an internal IIR filter. It effectively reduces the bandwidth of the output signals

. The output of a

next measurement step is filter using the following formula:

tcoefficienfilter ADCdatatcoefficienfilteroldfiltereddata

filtereddata __)1_(__

_



where data_filtered_old is the data coming from the previous acquisition, and data_ADC is the

data coming from the ADC before IIR filtering.

The IIR filter can be configured using the filter[2:0] bits in control register 0xF5 with the following

options:

Since most pressure sensors do not sample continuously, filtering can suffer from signals with a frequency higher than the

sampling rate of the sensor. E.g. environmental fluctuations caused by windows being opened and closed might have a frequency

<5 Hz. Consequently, a sampling rate of ODR = 10 Hz is sufficient to obey the Nyquist theorem.

Datasheet

BMP280 Digital Pressure Sensor

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BST-BMP280-DS001-10 | Revision 1.12 | July 2014 Bosch Sensortec

third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.

Note: Specifications within this document are subject to change without notice. Not intended for publication.

Table 6: filter settings

filter[2:0]

Filter coefficient

Bandwidth

(ODR calculation see Table 14)

000

Filter off

Full

001

0.223 × ODR

010

0.092 × ODR

011

0.042 × ODR

100, others

0.021 × ODR

In order to find a suitable setting for filter, please consult chapter 3.4.

When writing to the register filter, the filter is reset. The next value will pass through the filter

and be the initial memory value for the filter. If temperature or pressure measurement is

skipped, the corresponding filter memory will be kept unchanged even though the output

registers are set to 0x80000. When the previously skipped measurement is re-enabled, the

output will be filtered using the filter memory from the last time when the measurement was not

skipped.

3.4 Filter selection

In order to select optimal settings, the following use cases are suggested:

Table 7: Recommended filter settings based on use cases

Use case

Mode

Over-

sampling

setting

osrs_p

osrs_t

IIR

filter

coeff.

(see

3.3.3)

IDD

[µA]

(see

3.7)

ODR

[Hz]

(see

3.8.2)

RMS

Noise

[cm]

(see

3.5)

handheld device

low-power

(e.g. Android)

Normal

Ultra high

resolution

×16

×2

247

10.0

4.0

handheld device

dynamic

(e.g. Android)

Normal

Standard

resolution

×4

×1

577

83.3

2.4

Weather

monitoring

(lowest power)

Forced

Ultra low

power

×1

Off

0.14

1/60

26.4

Elevator / floor

change detection

Normal

Standard

resolution

×4

×1

50.9

7.3

6.4

Drop detection

Normal

Low

power

×2

×1

Off

509

125

20.8

Indoor navigation

Normal

Ultra high

resolution

×16

×2

650

26.3

1.6

Datasheet

BMP280 Digital Pressure Sensor

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3.5 Noise

Noise depends on the oversampling and filter settings selected. The stated values were

determined in a controlled pressure environment and are based on the average standard

deviation of 32 consecutive measurement points taken at highest sampling speed. This is

needed in order to exclude long term drifts from the noise measurement.

Table 8: Noise in pressure

Typical RMS noise in pressure [Pa]

Oversampling setting

IIR filter coefficient

off

Ultra low power

3.3

1.9

1.2

0.9

0.4

Low power

2.6

1.5

1.0

0.6

0.4

Standard resolution

2.1

1.2

0.8

0.5

0.3

High resolution

1.6

1.0

0.6

0.4

0.2

Ultra high resolution

1.3

0.8

0.5

0.4

0.2

Table 9: Noise in temperature

Typical RMS noise in temperature [°C]

Temperature oversampling

IIR filter off

oversampling ×1

0.005

oversampling ×2

0.004

oversampling ×4

0.003

oversampling ×8

0.003

oversampling ×16

0.002

3.6 Power modes

The BMP280 offers three power modes: sleep mode, forced mode and normal mode. These

can be selected using the mode[1:0] bits in control register 0xF4.

Table 10: mode settings

mode[1:0]

Mode

Sleep mode

01 and 10

Forced mode

Normal mode

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3.6.1 Sleep mode

Sleep mode is set by default after power on reset. In sleep mode, no measurements are

performed and power consumption (IDDSM) is at a minimum. All registers are accessible; Chip-ID

and compensation coefficients can be read.

3.6.2 Forced mode

In forced mode, a single measurement is performed according to selected measurement and

filter options. When the measurement is finished, the sensor returns to sleep mode and the

measurement results can be obtained from the data registers. For a next measurement, forced

mode needs to be selected again. This is similar to BMP180 operation. Forced mode is

recommended for applications which require low sampling rate or host-based synchronization.

time

current

IDDSL

IDDSB

IDDP

IDDT

POR Mode[1:0] = 01

Measurement T

Measurement P

Measurement T

Measurement P

Measurement T

Data readout

osrs_t osrs_p

Write

settings Mode[1:0] = 01

Figure 3: Forced mode timing diagram

3.6.3 Normal mode

Normal mode continuosly cycles between an (active) measurement period and an (inactive)

standby period, whose time is defined by tstandby. The current in the standby period (IDDSB) is

slightly higher than in sleep mode. After setting the mode,measurement and filter options, the

last measurement results can be obtained from the data registers without the need of further

write accesses. Normal mode is recommended when using the IIR filter, and useful for

applications in which short-term disturbances (e.g. blowing into the sensor) should be filtered.

time

current

IDDSL

IDDSB

IDDP

IDDT

POR Mode[1:0] = 11

Measurement T

Measurement P

Measurement T

Measurement P

Measurement T

Data readout

when needed

osrs_t osrs_p

Write

settings

tstandby

Figure 4: Normal mode timing diagram

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The standby time is determined by the contents of the t_sb[2:0] bits in control register 0xF5

according to the table below:

Table 11: t_sb settings

t_sb[1:0]

tstandby [ms]

000

0.5

001

62.5

010

125

011

250

100

500

101

1000

110

2000

111

4000

3.6.4 Mode transition diagram

The supported mode transitions are displayed below. If the device is currently performing a

measurement, execution of mode switching commands is delayed until the end of the currently

running measurement period. Further mode change commands are ignored until the last mode

change command is executed. Mode transitions other than the ones shown below are tested for

stability but do not represent recommended use of the device.

Power OFF

(VDD or VDDIO = 0)

VDD and VDDIO

supplied

Mode[1:0] = 00

Mode[1:0] = 01

Sleep

Normal

(cyclic standby and

measurement periods)

Mode[1:0] = 11

Forced

(one measurement

period)

Mode[1:0] = 01

Figure 5: Mode transition diagram

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3.7 Current consumption

The current consumption depends on ODR and oversampling setting. The values given below

are normalized to an ODR of 1 Hz. The actual consumption at a given ODR can be calculated

by multiplying the consumption in Table 12 with the ODR used. The actual ODR is defined

either by the frequency at which the user sets forced measurements or by oversampling and

tstandby settings in normal mode in Table 14.

Table 12: Current consumption

Oversampling setting

Pressure

oversampling

Temperature

oversampling

IDD [µA] @ 1 Hz forced mode

Typ

Max

Ultra low power

×1

2.74

4.16

Low power

×2

×1

4.17

6.27

Standard resolution

×4

×1

7.02

10.50

High resolution

×8

×1

12.7

18.95

Ultra high resolution

×16

×2

24.8

36.85

3.8 Measurement timings

The rate at which measurements can be performed in forced mode depends on the

oversampling settings osrs_t and osrs_p. The rate at which they are performed in normal mode

depends on the oversampling setting settings osrs_t and osrs_p and the standby time tstandby. In

the following table the resulting ODRs are given only for the suggested osrs combinations.

3.8.1 Measurement time

The following table explains the typical and maximum measurement time based on selected

oversampling setting. The minimum achievable frequency is determined by the maximum

measurement time.

Table 13: measurement time

Oversampling

setting

Pressure

oversampling

Temperature

oversampling

Measurement

time [ms]

Measurement

rate [Hz]

Typ

Max

Typ

Min

Ultra low power

×1

5.5

6.4

181.8

155.6

Low power

×2

×1

7.5

8.7

133.3

114.6

Standard resolution

×4

×1

11.5

13.3

87.0

75.0

High resolution

×8

×1

19.5

22.5

51.3

44.4

Ultra high resolution

×16

×2

37.5

43.2

26.7

23.1

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3.8.2 Measurement rate in normal mode

The following table explains which measurement rates can be expected in normal mode based

on oversampling setting and tstandby.

Table 14: typical output data Rate (ODR) in normal mode [Hz]

Oversampling

setting

tstandby [ms]

0.5

62.5

125

250

500

1000

2000

4000

Ultra low power

166.67

14.71

7.66

3.91

1.98

0.99

0.50

0.25

Low power

125.00

14.29

7.55

3.88

1.97

0.99

0.50

0.25

Standard

resolution

83.33

13.51

7.33

3.82

1.96

0.99

0.50

0.25

High resolution

50.00

12.20

6.92

3.71

1.92

0.98

0.50

0.25

Ultra high

resolution

26.32

10.00

6.15

3.48

1.86

0.96

0.49

0.25

Table 15: Sensor timing according to recommended settings (based on use cases)

Use case

Mode

Over-

sampling

setting

osrs_p

osrs_t

IIR

filter

coeff.

(see

3.3.3)

Timing

ODR

[Hz]

(see

3.8.2)

[Hz]

(see

3.3.3)

handheld device

low-power (e.g.

Android)

Normal

Ultra high

resolution

×16

×2

tstandby =

62.5 ms

10.0

0.92

handheld device

dynamic (e.g.

Android)

Normal

Standard

resolution

×4

×1

tstandby =

0.5 ms

83.3

1.75

Weather

monitoring

(lowest power)

Forced

Ultra low

power

×1

Off

1/min

1/60

full

Elevator / floor

change

detection

Normal

Standard

resolution

×4

×1

tstandby =

125 ms

7.3

0.67

Drop detection

Normal

Low

power

×2

×1

Off

tstandby =

0.5 ms

125

full

Indoor

navigation

Normal

Ultra high

resolution

×16

×2

tstandby =

0.5 ms

26.3

0.55

3.9 Data readout

To read out data after a conversion, it is strongly recommended to use a burst read and not

address every register individually. This will prevent a possible mix-up of bytes belonging to

different measurements and reduce interface traffic. Data readout is done by starting a burst

read from 0xF7 to 0xFC. The data are read out in an unsigned 20-bit format both for pressure

and for temperature. It is strongly recommended to use the BMP280 API, available from Bosch

Sensortec, for readout and compensation. For details on memory map and interfaces, please

consult chapters 3.12 and 5 respectively.

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The timing for data readout in forced mode should be done so that the maximum measurement

times (see chapter 3.8.1) are respected. In normal mode, readout can be done at a speed

similar to the expected data output rate (see chapter 3.8.2). After the values of ‘ut’ and ‘up’ have

been read, the actual pressure and temperature need to be calculated using the compensation

parameters stored in the device. The procedure is elaborated in chapter 3.11.

3.10 Data register shadowing

In normal mode, measurement timing is not necessarily synchronized to readout. This means

that new measurement results may become available while the user is reading the results from

the previous measurement. In this case, shadowing is performed in order to guarantee data

consistency. Shadowing will only work if all data registers are read in a single burst read.

Therefore, the user must use burst reads if he does not synchronize data readout with the

measurement cycle. Using several independent read commands may result in inconsistent data.

If a new measurement is finished and the data registers are still being read, the new

measurement results are transferred into shadow data registers. The content of shadow

registers is transferred into data registers as soon as the user ends the burst read, even if not all

data registers were read. Reading across several data registers can therefore only be

guaranteed to be consistent within one measurement cycle if a single burst read command is

used. The end of the burst read is marked by the rising edge of CSB pin in SPI case or by the

recognition of a stop condition in I2C case. After the end of the burst read, all user data

registers are updated at once.

3.11 Output compensation

The BMP280 output consists of the ADC output values. However, each sensing element

behaves differently, and actual pressure and temperature must be calculated using a set of

calibration parameters. The recommended calculation in chapter 3.11.3 uses fixed point

arithmetic. In high-level languages like Matlab™ or LabVIEW™, fixed-point code may not be

well supported. In this case the floating-point code in appendix 8.1 can be used as an

alternative. For 8-bit micro controllers, the variable size may be limited. In this case a simplified

32 bit integer code with reduced accuracy is given in appendix 8.2.

3.11.1 Computational requirements

The table below shows the number of clock cycles needed for compensation calculations on a

32 bit Cortex-M3 micro controller with GCC optimization level -O2. This controller does not

contain a floating point unit, so all floating-point calculations are emulated. Floating point is only

recommended for PC applications where an FPU is present.

Table 16: Computational requirements for compensation formulas

Compensation of

Number of clock cycles (ARM Cortex-M3)

32 bit integer

64 bit integer

Double precision

Temperature

~46

–

~2400 9

Pressure

~112 10

~1400

~5400 9

Use only recommended for high-level programming languages like Matlab™ or LabVIEW™

Use only recommended for 8-bit micro controllers

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3.11.2 Trimming parameter readout

The trimming parameters are programmed into the devices’ non-volatile memory (NVM) during

production and cannot be altered by the customer. Each compensation word is a 16-bit signed

or unsigned integer value stored in two’s complement. As the memory is organized into 8-bit

words, two words must always be combined in order to represent the compensation word. The

8-bit registers are named calib00…calib25 and are stored at memory addresses 0x88…0xA1.

The corresponding compensation words are named dig_T# for temperature compensation

related values and dig_P# for pressure compensation related values. The mapping is shown in

Table 17.

Table 17: Compensation parameter storage, naming and data type

Address

LSB / MSB

content

Data type

0x88 / 0x89

dig_T1

unsigned short

0x8A / 0x8B

dig_T2

signed short

0x8C / 0x8D

dig_T3

signed short

0x8E / 0x8F

dig_P1

unsigned short

0x90 / 0x91

dig_P2

signed short

0x92 / 0x93

dig_P3

signed short

0x94 / 0x95

dig_P4

signed short

0x96 / 0x97

dig_P5

signed short

0x98 / 0x99

dig_P6

signed short

0x9A / 0x9B

dig_P7

signed short

0x9C / 0x9D

dig_P8

signed short

0x9E / 0x9F

dig_P9

signed short

0xA0 / 0xA1

reserved

3.11.3 Compensation formula

Please note that it is strongly advised to use the API available from Bosch Sensortec to perform

readout and compensation. If this is not wanted, the code below can be applied at the user’s

risk. Both pressure and temperature values are expected to be received in 20 bit format,

positive, stored in a 32 bit signed integer.

The variable t_fine (signed 32 bit) carries a fine resolution temperature value over to the

pressure compensation formula and could be implemented as a global variable.

The data type “BMP280_S32_t” should define a 32 bit signed integer variable type and can

usually be defined as “long signed int”.

The data type “BMP280_U32_t” should define a 32 bit unsigned integer variable type and can

usually be defined as “long unsigned int”.

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For best possible calculation accuracy, 64 bit integer support is needed. If this is not possible on

your platform, please see appendix 8.2 for a 32 bit alternative.

The data type “BMP280_S64_t” should define a 64 bit signed integer variable type, which on

most supporting platforms can be defined as “long long signed int”. The revision of the code is

rev.1.1.

// Returns temperature in DegC, resolution is 0.01 DegC. Output value of “5123” equals 51.23 DegC.

// t_fine carries fine temperature as global value

BMP280_S32_t t_fine;

BMP280_S32_t bmp280_compensate_T_int32(BMP280_S32_t adc_T)

{

BMP280_S32_t var1, var2, T;

var1 = ((((adc_T>>3) – ((BMP280_S32_t)dig_T1<<1))) * ((BMP280_S32_t)dig_T2)) >> 11;

var2 = (((((adc_T>>4) – ((BMP280_S32_t)dig_T1)) * ((adc_T>>4) – ((BMP280_S32_t)dig_T1))) >> 12) *

((BMP280_S32_t)dig_T3)) >> 14;

t_fine = var1 + var2;

T = (t_fine * 5 + 128) >> 8;

return T;

}

“”–

// Returns pressure in Pa as unsigned 32 bit integer in Q24.8 format (24 integer bits and 8 fractional bits).

// Output value of “24674867” represents 24674867/256 = 96386.2 Pa = 963.862 hPa

BMP280_U32_t bmp280_compensate_P_int64(BMP280_S32_t adc_P)

{

BMP280_S64_t var1, var2, p;

var1 = ((BMP280_S64_t)t_fine) – 128000;

var2 = var1 * var1 * (BMP280_S64_t)dig_P6;

var2 = var2 + ((var1*(BMP280_S64_t)dig_P5)<<17);

var2 = var2 + (((BMP280_S64_t)dig_P4)<<35);

var1 = ((var1 * var1 * (BMP280_S64_t)dig_P3)>>8) + ((var1 * (BMP280_S64_t)dig_P2)<<12);

var1 = (((((BMP280_S64_t)1)<<47)+var1))*((BMP280_S64_t)dig_P1)>>33;

if (var1 == 0)

{

return 0; // avoid exception caused by division by zero

}

p = 1048576-adc_P;

p = (((p<<31)-var2)*3125)/var1;

var1 = (((BMP280_S64_t)dig_P9) * (p>>13) * (p>>13)) >> 25;

var2 = (((BMP280_S64_t)dig_P8) * p) >> 19;

p = ((p + var1 + var2) >> 8) + (((BMP280_S64_t)dig_P7)<<4);

return (BMP280_U32_t)p;

3.12 Calculating pressure and temperature

The following figure shows the detailed algorithm for pressure and temperature measurement.

This algorithm is available to customers as reference C source code (“BMP28x_ API”) from

Bosch Sensortec and via its sales and distribution partners.

Please contact your Bosch Sensortec representative for details.

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4. Global memory map and register description

4.1 General remarks

All communication with the device is performed by reading from and writing to registers.

Registers have a width of 8 bits. There are several registers which are reserved; they should not

be written to and no specific value is guaranteed when they are read. For details on the

interface, consult chapter 5.

4.2 Memory map

The memory map is given in Table 18 below. Reserved registers are not shown.

Table 18: Memory map

state

temp_xlsb 0xFC 0 0 0 0 0x00

temp_lsb 0xFB 0x00

temp_msb 0xFA 0x80

press_xlsb 0xF9 0 0 0 0 0x00

press_lsb 0xF8 0x00

press_msb 0xF7 0x80

config 0xF5 spi3w_en[0] 0x00

ctrl_meas 0xF4 0x00

status 0xF3

measuring[0]

im_update[0]

0x00

reset 0xE0 0x00

id 0xD0 0x58

calib25...calib00 0xA1…0x88 individual

Registers:

Reserved

registers

Calibration

data

Control

registers

Data

registers

Status

registers

Revision Reset

Type: do not

write read only read / write read only read only read only write only

press_lsb<7:0>

press_msb<7:0>

mode[1:0]

t_sb[2:0]

filter[2:0]

osrs_p[2:0]

calibration data

press_xlsb<7:4>

temp_xlsb<7:4>

temp_lsb<7:0>

temp_msb<7:0>

chip_id[7:0]

osrs_t[2:0]

reset[7:0]

4.3 Register description

4.3.1 Register 0xD0 “id”

The “id” register contains the chip identification number chip_id[7:0], which is 0x58. This number

can be read as soon as the device finished the power-on-reset.

4.3.2 Register 0xE0 “reset”

The “reset” register contains the soft reset word reset[7:0]. If the value 0xB6 is written to the

than 0xB6 has no effect. The readout value is always 0x00.

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4.3.3 Register 0xF3 “status”

The “status” register contains two bits which indicate the status of the device.

Table 19: Register 0xF3 “status”

“status”

Name

Description

Bit 3

measuring[0]

Automatically set to ‘1’ whenever a conversion is running

and back to ‘0’ when the results have been transferred

to the data registers.

Bit 0

im_update[0]

Automatically set to ‘1’ when the NVM data are being

copied to image registers and back to ‘0’ when the

copying is done. The data are copied at power-on-reset

and before every conversion.

4.3.4 Register 0xF4 “ctrl_meas”

The “ctrl_meas” register sets the data acquisition options of the device.

Table 20: Register 0xF4 “ctrl_meas”

“ctrl_meas”

Name

Description

Bit 7, 6, 5

osrs_t[2:0]

Controls oversampling of temperature data. See chapter

3.3.2 for details.

Bit 4, 3, 2

osrs_p[2:0]

Controls oversampling of pressure data. See chapter

3.3.1 for details.

Bit 1, 0

mode[1:0]

Controls the power mode of the device. See chapter 3.6

for details.

Table 21: register settings osrs_p

osrs_p[2:0]

Pressure

oversampling

000

Skipped (output set to

0x80000)

001

oversampling ×1

010

oversampling ×2

011

oversampling ×4

100

oversampling ×8

101, Others

oversampling ×16

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Table 22: register settings osrs_t

osrs_t[2:0]

Temperature oversampling

000

Skipped (output set to 0x80000)

001

oversampling ×1

010

oversampling ×2

011

oversampling ×4

100

oversampling ×8

101, 110, 111

oversampling ×16

4.3.5 Register 0xF5 “config”

The “config” register sets the rate, filter and interface options of the device. Writes to the “config”

Table 23: Register 0xF5 “config”

“config”

Name

Description

Bit 7, 6, 5

t_sb[2:0]

Controls inactive duration tstandby in normal mode. See

chapter 3.6.3 for details.

Bit 4, 3, 2

filter[2:0]

Controls the time constant of the IIR filter. See chapter

3.3.3 for details.

Bit 0

spi3w_en[0]

Enables 3-wire SPI interface when set to ‘1’. See

chapter 5.3 for details.

4.3.6 Register 0xF7…0xF9 “press” (_msb, _lsb, _xlsb)

The “press” register contains the raw pressure measurement output data up[19:0]. For details

on how to read out the pressure and temperature information from the device, please consult

chapter3.9.

Table 24: Register 0xF7 … 0xF9 “press”

“press”

Name

Description

0xF7

press_msb[7:0]

Contains the MSB part up[19:12] of the raw pressure

measurement output data.

0xF8

press_lsb[7:0]

Contains the LSB part up[11:4] of the raw pressure

measurement output data.

0xF9 (bit 7, 6, 5, 4)

press_xlsb[3:0]

Contains the XLSB part up[3:0] of the raw pressure

measurement output data. Contents depend on

temperature resolution, see table 5.

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4.3.7 Register 0xFA…0xFC “temp” (_msb, _lsb, _xlsb)

The “temp” register contains the raw temperature measurement output data ut[19:0]. For details

on how to read out the pressure and temperature information from the device, please consult

chapter 3.9.

Table 25: Register 0xFA … 0xFC “temp”

“press”

Name

Description

0xFA

temp_msb[7:0]

Contains the MSB part ut[19:12] of the raw temperature

measurement output data.

0xFB

temp_lsb[7:0]

Contains the LSB part ut[11:4] of the raw temperature

measurement output data.

0xFC (bit 7, 6, 5, 4)

temp_xlsb[3:0]

Contains the XLSB part ut[3:0] of the raw temperature

measurement output data. Contents depend on pressure

resolution, see Table 4.

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5. Digital interfaces

The BMP280 supports the I²C and SPI digital interfaces; it acts as a slave for both protocols.

The I²C interface supports the Standard, Fast and High Speed modes. The SPI interface

supports both SPI mode ‘00’ (CPOL = CPHA = ‘0’) and mode ‘11’ (CPOL = CPHA = ‘1’) in 4-

wire and 3-wire configuration.

The following transactions are supported:

 Single byte write

 multiple byte write (using pairs of register addresses and register data)

 single byte read

 multiple byte read (using a single register address which is auto-incremented)

5.1 Interface selection

Interface selection is done automatically based on CSB (chip select) status. If CSB is connected

to VDDIO, the I²C interface is active. If CSB is pulled down, the SPI interface is activated. After

CSB has been pulled down once (regardless of whether any clock cycle occurred), the I²C

interface is disabled until the next power-on-reset. This is done in order to avoid inadvertently

decoding SPI traffic to another slave as I²C data. Since power-on-reset is only executed when

both VDD and VDDIO are established, there is no risk of incorrect protocol detection due to power-

up sequence used. However, if I²C is to be used and CSB is not directly connected to VDDIO but

rather through a programmable pin, it must be ensured that this pin already outputs the VDDIO

level during power-on-reset of the device. If this is not the case, the device will be locked in SPI

mode and not respond to I²C commands.

5.2 I²C Interface

The I²C slave interface is compatible with Philips I²C Specification version 2.1. For detailed

timings refer to Table 27. All modes (standard, fast, high speed) are supported. SDA and SCL

are not pure open-drain. Both pads contain ESD protection diodes to VDDIO and GND. As the

devices does not perform clock stretching, the SCL structure is a high-Z input without drain

capability.

GND

VDDIO

output driver (only for SDI)

SDI /SCL high-z level shifter

GND

Figure 6: SDI/SCK ESD drawing

The 7-bit device address is 111011x. The 6 MSB bits are fixed. The last bit is changeable by

SDO value and can be changed during operation. Connecting SDO to GND results in slave

address 1110110 (0x76); connection it to VDDIO results in slave address 1110111 (0x77), which

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is the same as BMP180’s I²C address. The SDO pin cannot be left floating; if left floating, the

I²C address will be undefined.

The I²C interface uses the following pins:

 SCK: serial clock (SCL)

 SDI: data (SDA)

 SDO: Slave address LSB (GND = ‘0’, VDDIO = ‘1’)

CSB must be connected to VDDIO to select I²C interface. SDI is bi-directional with open drain to

GND: it must be externally connected to VDDIO via a pull up resistor. Refer to chapter 6 for

connection instructions.

The following abbreviations will be used in the I²C protocol figures:

 S Start

 P Stop

 ACKS Acknowledge by slave

 ACKM Acknowledge by master

 NACKM Not acknowledge by master

5.2.1 I²C write

Writing is done by sending the slave address in write mode (RW = ‘0’), resulting in slave

address 111011X0 (‘X’ is determined by state of SDO pin. Then the master sends pairs of

depicted in Figure 7.

Start RW ACKS ACKS ACKS

1 1 1 0 1 1 X 0 1 0 1 0 0 0 0 0 bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0 …

ACKS ACKS Stop

…1 0 1 0 0 0 0 1 bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0

Slave Address

Control byte

Data byte

Control byte

Data byte

Figure 7: I²C multiple byte write (not auto-incremented)

5.2.2 I²C read

To be able to read registers, first the register address must be sent in write mode (slave address

111011X0). Then either a stop or a repeated start condition must be generated. After this the

slave is addressed in read mode (RW = ‘1’) at address 111011X1, after which the slave sends

out data from auto-incremented register addresses until a NOACKM and stop condition occurs.

This is depicted in Figure 8, where two bytes are read from register 0xF6 and 0xF7.

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Start RW ACKS ACKS

1 1 1 0 1 1 X 0 1 1 1 1 0 1 1 0

Start RW ACKS ACKM NOACKM Stop

1 1 1 0 1 1 X 1 bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0 bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0

Control byte

Data byte

Slave Address

Figure 8: I²C multiple byte read

5.3 SPI interface

The SPI interface is compatible with SPI mode ‘00’ (CPOL = CPHA = ‘0’) and mode ‘11’ (CPOL

= CPHA = ‘1’). The automatic selection between mode ‘00’ and ‘11’ is determined by the value

of SCK after the CSB falling edge.

The SPI interface has two modes: 4-wire and 3-wire. The protocol is the same for both. The 3-

wire mode is selected by setting ‘1’ to the register spi3w_en. The pad SDI is used as a data pad

in 3-wire mode.

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The SPI interface uses the following pins:

 CSB: chip select, active low

 SCK: serial clock

 SDI: serial data input; data input/output in 3-wire mode

 SDO: serial data output; hi-Z in 3-wire mode

Refer to chapter 6 for connection instructions.

CSB is active low and has an integrated pull-up resistor. Data on SDI is latched by the device at

SCK rising edge and SDO is changed at SCK falling edge. Communication starts when CSB

goes to low and stops when CSB goes to high; during these transitions on CSB, SCK must be

stable. The SPI protocol is shown in Figure 9. For timing details, please review Table 28.

CSB

SCK

SDI

AD6

AD5

AD4

AD3

AD2

AD1

AD0

DI5

DI4

DI3

DI2

DI1

DI0

DI7

DI6

SDO

DO5

DO4

DO3

DO2

DO1

DO0

DO7

DO6

tri-state

Figure 9: SPI protocol (shown for mode ‘11’ in 4-wire configuration)

In SPI mode, only 7 bits of the register addresses are used; the MSB of register address is not

used and replaced by a read/write bit (RW = ‘0’ for write and RW = ‘1’ for read).

Example: address 0xF7 is accessed by using SPI register address 0x77. For write access, the

byte 0x77 is transferred, for read access, the byte 0xF7 is transferred.

5.3.1 SPI write

Writing is done by lowering CSB and sending pairs control bytes and register data. The control

bytes consist of the SPI register address (= full register address without bit 7) and the write

command (bit7 = RW = ‘0’). Several pairs can be written without raising CSB. The transaction is

ended by a raising CSB. The SPI write protocol is depicted in Figure 10.

Start

RW RW Stop

0 1 1 1 0 1 0 0 bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0 0 1 1 1 0 1 0 1 bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0

Control byte

CSB

Data byte

Data register - adress F5h

CSB

Control byte

Data byte

Data register - address F4h

Figure 10: SPI multiple byte write (not auto-incremented)

5.3.2 SPI read

Reading is done by lowering CSB and first sending one control byte. The control bytes consist

of the SPI register address (= full register address without bit 7) and the read command (bit 7 =

RW = ‘1’). After writing the control byte, data is sent out of the SDO pin (SDI in 3-wire mode);

the register address is automatically incremented. The SPI read protocol is shown in Figure 11.

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Start

RW Stop

1 1 1 1 0 1 1 0 bit15 bit14 bit13 bit12 bit11 bit10 bit9 bit8 bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0

CSB

Data byte

Data register - address F7h

CSB

Control byte

Data byte

Data register - address F6h

Figure 11: SPI multiple byte read

5.4 Interface parameter specification

5.4.1 General interface parameters

The general interface parameters are given in Table 26 below.

Table 26: interface parameters

Parameter

Symbol

Condition

Min

Typ

Max

Units

Input – low level

Vil_si

VDDIO=1.2V to 3.6V

0.2 *

VDDIO

Input – high level

Vih_si

VDDIO=1.2V to 3.6V

0.8 *

VDDIO

Output – low level for I2C

Vol_SDI

VDDIO=1.62V, iol=3 mA

0.2 *

VDDIO

Output – low level for I2C

Vol_SDI

_1.2

VDDIO=1.20V, iol=3 mA

0.23 *

VDDIO

Output – low level

Vol_SD

VDDIO=1.62V, iol=1 mA

0.2 *

VDDIO

Output – low level

Vol_SD

O_1.2

VDDIO=1.20V, iol=1 mA

0.23 *

VDDIO

Output – high level

Voh

VDDIO=1.62V, ioh=1

(SDO, SDI)

0.8 *

VDDIO

Output – high level

Voh_1.2

VDDIO=1.2V, ioh=1 mA

(SDO, SDI)

0.6 *

VDDIO

Pull-up resistor

Rpull

Internal pull-up

resistance to VDDIO

120

190

kΩ

I2C bus load capacitor

On SDI and SCK

400

5.4.2 I²C timings

For I²C timings, the following abbreviations are used:

 “S&F mode” = standard and fast mode

 “HS mode” = high speed mode

 Cb = bus capacitance on SDA line

All other naming refers to I²C specification 2.1 (January 2000).

The I²C timing diagram is shown in

Figure 12. The corresponding values are given in Table 27.

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tHDDAT

tBUF

SDI

SCK

SDI

tLOW

tHDSTA

tSUSTA

tHIGH

tSUDAT

tSUSTO

Figure 12: I²C timing diagram

Table 27: I²C timings

Parameter

Symbol

Condition

Min

Typ

Max

Units

SDI setup time

tSU;DAT

S&F Mode

HS mode

160

SDI hold time

tHD;DAT

S&F Mode, Cb≤100 pF

S&F Mode, Cb≤400 pF

HS mode, Cb≤100 pF

HS mode, Cb≤400 pF

115

150

SCK low pulse

tLOW

HS mode, Cb≤100 pF

VDDIO = 1.62 V

160

SCK low pulse

tLOW

HS mode, Cb≤100 pF

VDDIO = 1.2 V

210

The above-mentioned I2C specific timings correspond to the following internal added delays:

 Input delay between SDI and SCK inputs: SDI is more delayed than SCK by typically

100 ns in Standard and Fast Modes and by typically 20 ns in High Speed Mode.

 Output delay from SCK falling edge to SDI output propagation is typically 140 ns in

Standard and Fast Modes and typically 70 ns in High Speed Mode.

5.4.3 SPI timings

The SPI timing diagram is in Figure 13, while the corresponding values are given in Table 28.

All timings apply both to 4- and 3-wire SPI.

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CSB

SCK

T_setup_csb

T_low_sck

T_high_sck

T_hold_csb

SDI

T_setup_sdi

T_hold_sdi

SDO

T_delay_sdo

Figure 13: SPI timing diagram

Table 28: SPI timings

Parameter

Symbol

Condition

Min

Typ

Max

Units

SPI clock input frequency

F_spi

MHz

SCK low pulse

T_low_sck

SCK high pulse

T_high_sck

SDI setup time

T_setup_sdi

SDI hold time

T_hold_sdi

SDO output delay

T_delay_sdo

25pF load, VDDIO=1.6V min

SDO output delay

T_delay_sdo

25pF load, VDDIO=1.2V min

CSB setup time

T_setup_csb

CSB hold time

T_hold_csb

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6. Pin-out and connection diagram

6.1 Pin-out

TOP VIEW

(pads not visible)

VDD

GND

VDDIO

SDO

GND

CSB

SDI

SCK

BOTTOM VIEW

(pads visible)

VDD

GND

VDDIO

SDO

GND

CSB

SDI

SCK

Vent hole Pin 1

marker

Figure 14: Pin-out top and bottom view

Table 29: Pin description

Name

I/O Type

Description

Connect to

SPI 4W

SPI 3W

I²C

GND

Supply

Ground

GND

CSB

Chip select

CSB

VDDIO

SDI

In/Out

Serial data input

SDI

SDI/SDO

SDA

SCK

Serial clock input

SCK

SCL

SDO

In/Out

Serial data output

SDO

DNC

GND for

default

address

VDDIO

Supply

Digital interface

supply

VDDIO

GND

Supply

Ground

GND

VDD

Supply

Analog supply

VDD

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6.2 Connection diagram 4-wire SPI

Figure 15: 4-wire SPI connection diagram (Pin1 marking indicated)

Note: the recommended value for C1, C2 is 100 nF.

TOP VIEW

(pads not visible)

VDD

GND

VDDIO

SDO

GND

CSB

SDI

SCK

SDI

SCK

VDDIO

VDD

SDO

CSB

Vent hole

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6.3 Connection diagram 3-wire SPI

Figure 16: 3-wire SPI connection diagram (Pin1 marking indicated)

Note: the recommended value for C1, C2 is 100 nF.

TOP VIEW

(pads not visible)

VDD

GND

VDDIO

SDO

GND

CSB

SDI

SCK

SDI/SDO

SCK

VDDIO

VDD

CSB

Vent hole

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6.4 Connection diagram I2C

Figure 17: I²C connection diagram (Pin1 marking indicated)

Notes:

 The recommended value for C1, C2 is 100 nF.

 A direct connection between CSB and VDDIO is recommended. If CSB is detected as low

during startup, the interface will be locked into SPI mode. See chapter 5.1.

TOP VIEW

(pads not visible)

VDD

GND

VDDIO

SDO

GND

CSB

SDI

SCK

SDA

SCL

VDDIO

VDD

I2C address bit 0

GND: '0'; VDDIO: '1'

Vent hole

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7. Package, reel and environment

7.1 Outline dimensions

The sensor housing is an 8-pin metal-lid LGA 2.0 × 2.5× 0.95 mm3 package. Its dimensions are

depicted in Figure 18.

Figure 18: Package outline dimensions for top, bottom and side view

Note: General tolerances are ±50 µm (linear) and ±1° µm (angular)

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7.2 Landing pattern recommendation

For the design of the landing pattern, the following dimensioning is recommended:

Figure 19: Recommended landing pattern (top view); dimensions are in mm

Note: red areas demark exposed PCB metal pads.

• In case of a solder mask defined (SMD) PCB process, the land dimensions should be

defined by solder mask openings. The underlying metal pads are larger than these openings.

• In case of a non solder mask defined (NSMD) PCB process, the land dimensions should

be defined in the metal layer. The mask openings are larger than the these metal pads.

0.35

2.50

0.65

0.5

0.55

2.0

0.325

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7.3 Marking

7.3.1 Mass production devices

Table 30: Marking of mass production samples

Labeling

Name

Symbol

Remark

Lot counter

CCC

3 alphanumeric digits, variable

to generate mass production trace-code

Product number

1 alphanumeric digit, fixed

to identify product type, T = “K”

“K” is associated with the product BMP280

(part number 0 273 300 354)

Sub-con ID

1 alphanumeric digit, variable to

identify sub-con (L = “A” or L = “U” or L = “P”)

Orientation

marker



Vent hole

7.3.2 Engineering samples

Table 31: Marking of engineering samples

Labeling

Name

Symbol

Remark

Eng. Sample ID

1 alphanumeric digit, fixed to identify

engineering sample, N = “ * ” or “e” or “E”

Sample ID

2 alphanumeric digits, variable

to generate trace-code

Counter ID

2 alphanumeric digits, variable

to generate trace-code

Orientation

marker



Vent hole

XXN

CC 

CCC

TL 

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7.4 Soldering guidelines

The moisture sensitivity level of the BMP280 sensors corresponds to JEDEC Level 1, see also:

 IPC/JEDEC J-STD-020C “Joint Industry Standard: Moisture/Reflow Sensitivity

Classification for non-hermetic Solid State Surface Mount Devices”

 IPC/JEDEC J-STD-033A “Joint Industry Standard: Handling, Packing, Shipping and Use of

Moisture/Reflow Sensitive Surface Mount Devices”.

The sensor fulfils the lead-free soldering requirements of the above-mentioned IPC/JEDEC

standard, i.e. reflow soldering with a peak temperature up to 260°C. The minimum height of the

solder after reflow shall be at least 50µm. This is required for good mechanical decoupling

between the sensor device and the printed circuit board (PCB).

Figure 20: Soldering profile

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7.5 Tape and reel specification

7.5.1 Dimensions

Figure 21: Tape and Reel dimensions

Quantity per reel: 10 kpcs.

7.5.2 Orientation within the reel

reel direction

Figure 22: Orientation within tape

1 2 3 4

8 7 6 5

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7.6 Mounting and assembly recommendations

In addition to “Handling, soldering & mounting instructions BMP280”, the following

recommendations should be taken into consideration when mounting a pressure sensor on a

printed-circuit board (PCB):

 The clearance above the metal lid shall be 0.1mm at minimum.

 For the device housing appropriate venting needs to be provided in case the ambient

pressure shall be measured.

 Liquids shall not come into direct contact with the device.

 During operation the sensor chip is sensitive to light, which can influence the accuracy of

the measurement (photo-current of silicon). The position of the vent hole minimizes the

light exposure of the sensor chip. Nevertheless, BST recommends to avoid the

exposure of BMP280 to strong light sources.

 Soldering may not be done using vapor phase processes since the sensor might be

damaged.

7.7 Environmental safety

7.7.1 RoHS

The BMP280 sensor meets the requirements of the EC restriction of hazardous substances

(RoHS) directive, see also:

Directive 2002/95/EC of the European Parliament and of the Council of 8 September

2011 on the restriction of the use of certain hazardous substances in electrical and

electronic equipment.

7.7.2 Halogen content

The BMP280 is halogen-free. For more details on the analysis results please contact your

Bosch Sensortec representative.

7.7.3 Internal package structure

Within the scope of Bosch Sensortec’s ambition to improve its products and secure the mass

product supply, Bosch Sensortec qualifies additional sources (e.g. 2nd source) for the LGA

package of the BMP280.

While Bosch Sensortec took care that all of the technical packages parameters are described

above are 100% identical for all sources, there can be differences in the chemical content and

the internal structural between the different package sources.

However, as secured by the extensive product qualification process of Bosch Sensortec, this

has no impact to the usage or to the quality of the BMP280 product.

8. Appendix 1: Computation formulae for 32 bit systems

8.1 Compensation formula in floating point

Please note that it is strongly advised to use the API available from Bosch Sensortec to perform

readout and compensation. If this is not wanted, the code below can be applied at the user’s

risk. Both pressure and temperature values are expected to be received in 20 bit format,

positive, stored in a 32 bit signed integer.

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The variable t_fine (signed 32 bit) carries a fine resolution temperature value over to the

pressure compensation formula and could be implemented as a global variable.

The data type “BMP280_S32_t” should define a 32 bit signed integer variable type and could

usually be defined as “long signed int”. The revision of the code is rev.1.1.

// Returns temperature in DegC, double precision. Output value of “51.23” equals 51.23 DegC.

// t_fine carries fine temperature as global value

BMP280_S32_t t_fine;

double bmp280_compensate_T_double(BMP280_S32_t adc_T)

{

double var1, var2, T;

var1 = (((double)adc_T)/16384.0 – ((double)dig_T1)/1024.0) * ((double)dig_T2);

var2 = ((((double)adc_T)/131072.0 – ((double)dig_T1)/8192.0) *

(((double)adc_T)/131072.0 – ((double) dig_T1)/8192.0)) * ((double)dig_T3);

t_fine = (BMP280_S32_t)(var1 + var2);

T = (var1 + var2) / 5120.0;

return T;

}

// Returns pressure in Pa as double. Output value of “96386.2” equals 96386.2 Pa = 963.862 hPa

double bmp280_compensate_P_double(BMP280_S32_t adc_P)

{

double var1, var2, p;

var1 = ((double)t_fine/2.0) – 64000.0;

var2 = var1 * var1 * ((double)dig_P6) / 32768.0;

var2 = var2 + var1 * ((double)dig_P5) * 2.0;

var2 = (var2/4.0)+(((double)dig_P4) * 65536.0);

var1 = (((double)dig_P3) * var1 * var1 / 524288.0 + ((double)dig_P2) * var1) / 524288.0;

var1 = (1.0 + var1 / 32768.0)*((double)dig_P1);

if (var1 == 0.0)

{

return 0; // avoid exception caused by division by zero

}

p = 1048576.0 – (double)adc_P;

p = (p – (var2 / 4096.0)) * 6250.0 / var1;

var1 = ((double)dig_P9) * p * p / 2147483648.0;

var2 = p * ((double)dig_P8) / 32768.0;

p = p + (var1 + var2 + ((double)dig_P7)) / 16.0;

return p;

}

8.2 Compensation formula in 32 bit fixed point

Please note that it is strongly advised to use the API available from Bosch Sensortec to perform

readout and compensation. If this is not wanted, the code below can be applied at the user’s

risk. Both pressure and temperature values are expected to be received in 20 bit format,

positive, stored in a 32 bit signed integer.

The variable t_fine (signed 32 bit) carries a fine resolution temperature value over to the

pressure compensation formula and could be implemented as a global variable.

The data type “BMP280_S32_t” should define a 32 bit signed integer variable type and can

usually be defined as “long signed int”.

The data type “BMP280_U32_t” should define a 32 bit unsigned integer variable type and can

usually be defined as “long unsigned int”.

Compensating the pressure value with 32 bit integer has an accuracy of typically 1 Pa (1-

sigma). At very high filter levels this adds a noticeable amount of noise to the output values and

reduces their resolution.

// Returns temperature in DegC, resolution is 0.01 DegC. Output value of “5123” equals 51.23 DegC.

// t_fine carries fine temperature as global value

BMP280_S32_t t_fine;

BMP280_S32_t bmp280_compensate_T_int32(BMP280_S32_t adc_T)

{

BMP280_S32_t var1, var2, T;

Datasheet

BMP280 Digital Pressure Sensor

Page 46

BST-BMP280-DS001-10 | Revision 1.12 | July 2014 Bosch Sensortec

third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.

Note: Specifications within this document are subject to change without notice. Not intended for publication.

var1 = ((((adc_T>>3) – ((BMP280_S32_t)dig_T1<<1))) * ((BMP280_S32_t)dig_T2)) >> 11;

var2 = (((((adc_T>>4) – ((BMP280_S32_t)dig_T1)) * ((adc_T>>4) – ((BMP280_S32_t)dig_T1))) >> 12) *

((BMP280_S32_t)dig_T3)) >> 14;

t_fine = var1 + var2;

T = (t_fine * 5 + 128) >> 8;

return T;

}

// Returns pressure in Pa as unsigned 32 bit integer. Output value of “96386” equals 96386 Pa = 963.86 hPa

BMP280_U32_t bmp280_compensate_P_int32(BMP280_S32_t adc_P)

{

BMP280_S32_t var1, var2;

BMP280_U32_t p;

var1 = (((BMP280_S32_t)t_fine)>>1) – (BMP280_S32_t)64000;

var2 = (((var1>>2) * (var1>>2)) >> 11 ) * ((BMP280_S32_t)dig_P6);

var2 = var2 + ((var1*((BMP280_S32_t)dig_P5))<<1);

var2 = (var2>>2)+(((BMP280_S32_t)dig_P4)<<16);

var1 = (((dig_P3 * (((var1>>2) * (var1>>2)) >> 13 )) >> 3) + ((((BMP280_S32_t)dig_P2) * var1)>>1))>>18;

var1 =((((32768+var1))*((BMP280_S32_t)dig_P1))>>15);

if (var1 == 0)

{

return 0; // avoid exception caused by division by zero

}

p = (((BMP280_U32_t)(((BMP280_S32_t)1048576)-adc_P)-(var2>>12)))*3125;

if (p < 0x80000000)

{

p = (p << 1) / ((BMP280_U32_t)var1);

}

else

{

p = (p / (BMP280_U32_t)var1) * 2;

}

var1 = (((BMP280_S32_t)dig_P9) * ((BMP280_S32_t)(((p>>3) * (p>>3))>>13)))>>12;

var2 = (((BMP280_S32_t)(p>>2)) * ((BMP280_S32_t)dig_P8))>>13;

p = (BMP280_U32_t)((BMP280_S32_t)p + ((var1 + var2 + dig_P7) >> 4));

return p;

}

Datasheet

BMP280 Digital Pressure Sensor

Page 47

BST-BMP280-DS001-10 | Revision 1.12 | July 2014 Bosch Sensortec

third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.

Note: Specifications within this document are subject to change without notice. Not intended for publication.

9. Legal disclaimer

9.1 Engineering samples

Engineering Samples are marked with an asterisk (*) or (e) or (E). Samples may vary from the

valid technical specifications of the product series contained in this data sheet. They are

therefore not intended or fit for resale to third parties or for use in end products. Their sole

purpose is internal client testing. The testing of an engineering sample may in no way replace

the testing of a product series. Bosch Sensortec assumes no liability for the use of engineering

samples. The Purchaser shall indemnify Bosch Sensortec from all claims arising from the use of

engineering samples.

9.2 Product use

Bosch Sensortec products are developed for the consumer goods industry. They are not

designed or approved for use in military applications, life-support appliances, safety-critical

automotive applications and devices or systems where malfunctions of these products can

reasonably be expected to result in personal injury. They may only be used within the

parameters of this product data sheet.

The resale and/or use of products are at the Purchaser’s own risk and the Purchaser’s own

responsibility.

The Purchaser shall indemnify Bosch Sensortec from all third party claims arising from any

product use not covered by the parameters of this product data sheet or not approved by Bosch

Sensortec and reimburse Bosch Sensortec for all costs in connection with such claims.

The Purchaser accepts the responsibility to monitor the market for the purchased products,

particularly with regard to product safety, and inform Bosch Sensortec without delay of any

security relevant incidents.

9.3 Application examples and hints

With respect to any examples or hints given herein, any typical values stated herein and/or any

information regarding the application of the device, Bosch Sensortec hereby disclaims any and

all warranties and liabilities of any kind, including without limitation warranties of non-

infringement of intellectual property rights or copyrights of any third party. The information given

in this document shall in no event be regarded as a guarantee of conditions or characteristics.

They are provided for illustrative purposes only and no evaluation regarding infringement of

intellectual property rights or copyrights or regarding functionality, performance or error has

been made.

Datasheet

BMP280 Digital Pressure Sensor

Page 48

BST-BMP280-DS001-10 | Revision 1.12 | July 2014 Bosch Sensortec

third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.

Note: Specifications within this document are subject to change without notice. Not intended for publication.

10. Document history and modification

Rev. No

Chapter

Description of modification/changes

Date

0.1

Document creation

2012-08-06

Update of preliminary versions

1.0

9.2

Change of product use

2013-11-26

Table 2

Update of min/max data (only for restricted version)

Added comment on the sampling rate

1.1

1, 3.3.1

Changed value for resolution, values for osrs_p

settings changed

2014-02-10

5.2

Changed sentence and added drawing

2014-02-18

3.7

Added max values for current consumption

2014-05-08

1.11

4.5.3

Modified write in normal mode

2014-06-25

5.2

Modified SDI/SCK ESD drawing

1.12

Changed min/max values for standby current for 25

°C

2014-07-12

Datasheet

BMP280 Digital Pressure Sensor

Page 49

BST-BMP280-DS001-10 | Revision 1.12 | July 2014 Bosch Sensortec

third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.

Note: Specifications within this document are subject to change without notice. Not intended for publication.

1.12

Changed min/max values for standby current, only

valid for 25 °C

2014-07-12

Bosch Sensortec GmbH

Gerhard-Kindler-Strasse 8

72770 Reutlingen / Germany

contact@bosch-sensortec.com

www.bosch-sensortec.com

Modifications reserved | Printed in Germany

Specifications subject to change without notice

Document number: BST-BMP280-DS001-10

Revision_1.12_072014

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