Information

BMA280
Data sheet
Page 16
BST-BMA280-DS000-11 | Revision 1.8 | August 2014 Bosch Sensortec
© Bosch Sensortec GmbH reserves all rights even in the event of industrial property rights. We reserve all rights of disposal such as copying and passing on to
third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.
Note: Specifications within this document are subject to change without notice.
State
Sleep phase
Active phase
Sample
Sample
Sample Sample Sample Sample
t
SLEEP
t
Settle
Settle
Settle
Sample
t
SLEEP
t
ACTIVE
Figure 3: Timing Diagram for low-power mode 1/2, EDT
When (0x12) sleeptimer_mode is set to ‘1’, the equidistant-sampling mode (EST) is selected.
The use of the EST mode is recommended when the FIFO is used since it ensures that
equidistant samples are sampled into the FIFO regardless of whether the active phase is
extended by active interrupt engines or interface activity. In EST mode the sleep time t
SLEEP
is
defined as shown in Figure 4. The FIFO sampling time t
SAMPLE
is the sum of the sleep time t
SLEEP
and the sensor data sampling time t
SSMP
. Since interrupt engines can extend the active phase to
exceed the sleep time t
SLEEP
, equidistant sampling is only guaranteed if the bandwidth has been
chosen such that 1/(2 * bw) = n * t
SLEEP
where n is an integer. If this condition is infringed,
equidistant sampling is not possible. Once the sleep time has elapsed the device will store the
next available sample in the FIFO. This set-up condition is not recommended as it may result in
timing jitter.
State
Sleep phase
Active phase
Sample
Sample
Sample Sample Sample Sample
t
Settle
Settle
Settle
Sample
Settle
Sample
t
SLEEP
t
SLEEP
t
SLEEP
t
SAMPLE
t
SAMPLE
t
SAMPLE
Sampled into FIFO
t
SSMP
Figure 4: Timing Diagram for low-power mode 1/2, EST