Datasheet

Data Sheet
BMA456
Page 51
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.
4.11. Non-Volatile Memory
The registers NV_CONF and OFFSET_0 to OFFSET_2 have an NVM backup which are accessible
by the user.
The content of the NVM is loaded to the image registers after a reset (either POR or softreset). As long
as the image update is in progress, STATUS.cmd_rdy is 0b0, otherwise it is 0b1.
The image registers can be read and written like any other register.
Writing to the NVM is a 4-step procedure:
1. Set PWR_CONF.adv_power_save = 0b0
2. Write the new contents to the image registers.
3. Write 0b1 to bit NVM_CONF.nvm_prog_en in order to unlock the NVM.
4. Write prog_nvm to the CMD register to trigger the write process.
Writing to the NVM always renews the entire NVM contents. It is possible to check the write status by
reading STATUS.cmd_rdy. While STATUS.cmd_rdy = 0b0, the write process is still in progress; when
STATUS.cmd_rdy = 0b1, writing is completed. An NVM write cycle can only be initiated, if
PWR_CONF.adv_power_save = 0b0.
Until boot phase is finished (after POR or softreset), the serial interface is not operational. The NVM
shadow registers must not be accessed during an ongoing NVM command (initiated through the
Register CMD). In all other cases, register can be read or written.
As long as an NVM read (during sensor boot and soft reset) or an NVM write is ongoing, writes to
sensor registers are discarded, reads return the Register STATUS independent of the read address.
4.12. Soft-Reset
A softreset can be initiated at any time by writing the command softreset (0xB6) to register CMD. The
softreset performs a fundamental reset to the device which is largely equivalent to a power cycle.
Following a delay, all user configuration settings are overwritten with their default state (setting stored
in the NVM) wherever applicable. This command is functional in all operation modes but must not be
performed while NVM writing operation is in progress.