BMA400 interfaces to STM32 SPI mode, Interrupt Wake/Sleep under STM32Cube IDE

[Andy__]

Just starting on BMA400.

Any BMA400/STM32 example code that is same or similar ?   Battery-limited.  Use minimum energy.  Activity tracking.   Interrupt driven.  Plan to use "Sequencer" of STM32 HAL library.  MCU and BMA400 sleep for most time, waken on motion exceeding theshold, log data and sleep as soon as possible.

Is 4 wire SPI better than 3 wire in this case?   MCU has enough pins for CS and two interrupt pins?

What SPI data clock frequency you 'feel good', being reasonably fast so chip back to sleep soonest but NOT too high frequency to make too much EMI (electromagnetic interference)?   Distance between MCU and BMA400 is 15mm.  Chip pin plus trace capacitance about 10pF.  3 volts.  BMA400 is the only device on the SPI bus.  Data volume is 60 bytes per second.  STM32 and BMA400 max SPI freq is 17MHz. 

Many thanks

[FAE_CA1 · Accepted solution]

Hi,

Thanks for your inquiry.

Please see my previous reply to your another topic.

BMA400 4-wire SPI is better than 3-wire if your host process has enough GPIO pins. The SPI clock for BMA400 can be 2MHz, 4MHz, or 8MHz, but no higher than 10MHz.

Thanks.