Datasheet

BMP280 Digital Pressure Sensor

Page 12

BST-BMP280-DS001-19 | Revision 1.19 | January 2018

Bosch Sensortec

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

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)

No

Update filter memory using

filter memory, ADC value

and filter coefficient

No

Yes

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.