Bosch Sensortec"| BST-BMP581-DS004-02 19 | 74
Modifications reserved | Data subject to change
without notice Document number: BST-BMP581-DS004-02
4.4.2 Pressure and temperature oversampling ratio (OSR)
Oversampling extends the measurement time per measurement by the oversampling factor. Higher oversampling
factors offer decreased noise at the cost of higher power consumption.
Oversampling can be set individually for pressure and temperature in register fields OSR_CONFIG.osr_p and OSR_-
CONFIG.osr_t. The duration of the sampling phase, is given by t
conv_p
and t
conv_t
. Table 7: maximum nominal ODR
setting per OSR settings in NORMAL mode shows the maximum ODR for each oversampling setting. Recommended
settings are shown in Table 8: Oversampling settings .
Table 9: Oversampling settings
oversampling
oversampling
pressure
RMS noise
at 100kPa
CONTINUOUS
mode
Note: The noise values refer to the sensor-intrinsic noise. Already at standard resolution, the noise or fluctuations of
the air pressure itself may be higher than the noise of the sensor, and thus be dominant. This ambient noise is typically
stronger at lower frequencies. Any increase of the ODR does not reduce this type of noise, because this frequency
range is of interest for many applications and thus is not attenuated by the sensor. If low frequency noise is a problem
in a use case, it is recommended to employ low pass filtering, for example by using the build-in IIR-filter.
4.4.3 Configuration changes in NORMAL and CONTINUOUS mode
If any of these changes is applied during NORMAL and CONTINUOUS mode:
OSR_CONFIG.press_en
OSR_CONFIG.osr_t
OSR_CONFIG.osr_p
ODR_CONFIG.odr (NORMAL mode only)
Measurements will restart with the new settings after t
reconf
. If DEEP_SLEEP is enabled in NORMAL mode, it will start
after t
reconf_deep.
4.4.4 IIR filter
The BMP581 has a dedicated IIR filter built-in, that can be used to reduce noise caused by ambient disturbances. This
may for example be the opening of doors or windows, or wind blowing into the sensor. To suppress these disturbances
in the output data, the IIR filter can be enabled.
Please note that IIR filtering, like all low pass filtering, also reduces the bandwidth of the signal.
The filter function is the following:
=
× +
+ 1
where
is the filtered data from the previous acquisition, and
is the unfiltered data from the current
acquisition.
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