Data Sheet

Final Datasheet
BME280 Environmental sensor
Page 13
BST-BME280-DS001-10 | Revision 1.1 | May 2015 Bosch Sensortec
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Note: Specifications within this document are subject to change without notice.
3.3.2 Sleep mode
Sleep mode is entered by default after power on reset. In sleep mode, no measurements are
performed and power consumption (I
DDSM
) is at a minimum. All registers are accessible; Chip-ID
and compensation coefficients can be read. There are no special restrictions on interface
timings.
3.3.3 Forced mode
In forced mode, a single measurement is performed in accordance to the 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.
Using forced mode is recommended for applications which require low sampling rate or host-
based synchronization. The timing diagram is shown below.
time
POR Data readout
Write
settings
Mode[1:0] = 01
Measurement H
time
current
I
DDSL
I
DDSB
I
DDP
I
DDH
POR
Measurement T Measurement P
Write
settings
I
DDT
Measurement H Measurement T Measurement P
t
measure
Mode[1:0] = 01
cycle time = rate of force mode
Figure 4: Forced mode timing diagram
3.3.4 Normal mode
Normal mode comprises an automated perpetual cycling between an (active) measurement
period and an (inactive) standby period.
The measurements are performed in accordance to the selected measurement and filter
options. The standby time is determined by the setting t_sb[2:0] and can be set to between 0.5
and 1000 ms according to Table 27.
The total cycle time depends on the sum of the active time (see chapter 9) and standby time
t
standby
. The current in the standby period (I
DDSB
) is slightly higher than in sleep mode. After
setting the measurement and filter options and enabling normal mode, the last measurement
results can always be obtained at the data registers without the need of further write accesses.
Using normal mode is recommended when using the IIR filter. This is useful for applications in
which short-term disturbances (e.g. blowing into the sensor) should be filtered. The timing
diagram is shown below: