BMP388 datasheet(14/59 Pages) BOSCH

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Modifications reserved |Data subject to change without notice | Printed in Germany

Document number: BST-BMP388-DS001-07 Revision_1.7_112020

3.4.1. Pressure measurement

Pressure measurement can be enabled or skipped. Skipping the measurement could be useful if BMP388 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.

Enabling the measurement is selected by press_en bit in “PW_CTRL[0]” register (see 4.3.16). The oversampling setting

osr_p can be configured in “OSR[2:0]” register (see 4.3.17).

Table 6: osr_p settings8

Oversampling setting

osr_p

Pressure

oversampling

Typical pressure

resolution

Recommended

temperature

oversampling

Ultra low power

000

×1

16 bit / 2.64 Pa

×1

Low power

001

×2

17 bit / 1.32 Pa

×1

Standard resolution

010

×4

18 bit / 0.66 Pa

×1

High resolution

011

×8

19 bit / 0.33 Pa

×1

Ultra high resolution

100

×16

20 bit / 0.17 Pa

×2

Highest resolution

101

×32

21 bit / 0.085 Pa

×2

3.4.2. 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. Noise and increases the output resolution by one

bit, which is stored in the XLSB data register.

Enabling the measurement is selected by temp_en bit in “PW_CTRL[1]” register (see 4.3.16). The oversampling setting osr_t

can be configured in “OSR[5:3]” register (see 4.3.17).

Table 7: osrs_t settings

osr_t

Temperature

oversampling

Typical temperature

resolution

000

×1

16 bit / 0.0050 °C

001

×2

17 bit / 0.0025 °C

010

×4

18 bit / 0.0012 °C

011

×8

19 bit / 0.0006 °C

100

×16

20 bit / 0.0003 °C

101

×32

21 bit / 0.00015 °C

It is recommended to base the value of osr_t on the selected value of osrs_p as per Table 5

. 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.

8 Resolution of 24 bit e.g. OSR=32x and IIR>=b011

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