Datasheet

Bosch Sensortec | BME680 Datasheet
17 | 50
Modifications reserved |Data subject not change without notice | Printed in Germany
Document number: BST-BME680-DS001-00 Revision_1.0_072017
3.3 Measurement flow
Referring to Figure 1, the BME680 measurement period consists of a temperature, pressure and humidity measurement
with selectable oversampling. Moreover, it contains a heating phase for the gas sensor hot plate as well as a measurement
of the gas sensor resistance.
After the measurement period, the pressure and temperature data can be passed through an optional IIR filter, which removes
short-term fluctuations. For humidity and gas, such a filter is not needed and has not been implemented.
3.3.1 Temperature measurement
Temperature measurement can be enabled or skipped. Skipping the measurement is typically not recommended since
temperature information is used to compensate temperature influences in the other parameters. When enabled, several
oversampling options exist. The temperature measurement is controlled by the osrs_t<2:0> setting which is detailed in
Section 5.3.2.2. For the temperature measurement, oversampling is possible to reduce the noise. The resolution of the
temperature data depends on the IIR filter (see Section 5.3.2.4) and the oversampling setting:
 When the IIR filter is enabled, the temperature resolution is 20 bit
 When the IIR filter is disabled, the temperature resolution is 16 + (osrs_t – 1) bit, e.g. 18 bit when osrs_t is set to ‘3’
3.3.2 Pressure measurement
Pressure measurement can be enabled or skipped. When enabled, several oversampling options exist. The pressure
measurement is controlled by the osrs_p<2:0> setting which is detailed in Section 5.3.2. For the pressure measurement,
oversampling is possible to reduce noise. The resolution of the pressure data depends on the IIR filter (see Section 5.3.2.4)
and the oversampling setting:
 When the IIR filter is enabled, the pressure resolution is 20 bit
 When the IIR filter is disabled, the pressure resolution is 16 + (osrs_p – 1) bit, e.g. 18 bit when osrs_p is set to ‘3’
3.3.3 Humidity measurement
The humidity measurement can be enabled or skipped. When enabled, several oversampling options exist. The humidity
measurement is controlled by the osrs_h<2:0> setting, which is described in detail in Section 5.3.2.1. For the humidity
measurement, oversampling is possible to reduce noise. The resolution of the humidity measurement is fixed at 16 bit ADC
output.