Datasheet

Data Sheet
BMA456
Page 21
BST-BMA456-DS000-01 | Version 1.1 | October 2017 Bosch Sensortec
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Note: Specifications within this document are subject to change without notice.
Accelerometer data processing for low power mode
Low power mode can be enabled by PWR_CONF.adv_power_save=0b1 and
ACC_CONF.acc_perf_mode=0b0. In this power mode, the accelerometer regularly changes between
a suspend power mode phase where no measurement is performed and a performance power mode
phase, where data is acquired. The period of the duty cycle for changing between suspend and
performance mode will be determined by the output data rate (ACC_CONF.acc_odr). The output data
rate can be configured in one of 10 different valid ODR configurations going from 0.78Hz up to 400Hz.
The samples acquired during the normal mode phase will be averaged and the result will be the output
data. The number of averaged samples can be determined by the parameter ACC_CONF.acc_bwp
through the following formula:
averaged samples = 2
(Val(acc_bwp))
skipped samples = (1600/ODR)-averaged samples
A higher number of averaged samples will result in a lower noise level of the signal, but since the
performance power mode phase is increased, the power consumption will also rise.
Data Ready Interrupt
This interrupt fires whenever a new data sample set from accelerometer, and auxiliary sensor is
complete. This allows a low latency data readout. In non-latched mode, the interrupt and the flag in
Register INT_STATUS_1 are cleared automatically after 1/(3200Hz). If this automatic clearance is
unwanted, latched-mode can be used (see chapter 4.7).
In order to enable/use the data ready interrupt map it on the desired interrupt pin via INT_MAP_DATA.
Temperature Sensor
The temperature sensor has 8 bits. The temperature value is defined in Register TEMPERATURE and
updated every 1.28 s.
It is always on, when a sensor is active.
Value
Temperature
0x7F
150 °C
…
…
0x00
23 °C
…
…
0x81
-104 °C
0x80
Invalid
When there is no valid temperature information available (i.e. last measurement before the time
defined above), the temperature indicates an invalid value: 0x80.