Hi,
I am developing a custom board with nrf5340 SoC (nrfConnect SDK/zephyr) communicating with BMI270 via 8 MHz SPI. From BMI270 side I only need the high quality data, no detection algo or anything else.
The only thing I cannot get to work so far is reading the content of the FIFO.
The entire firmware works without FIFO already (interrupts, data readout, readout and configuration of all registers) - so, if I would not sometimes loose a frame (due to a variation in timing within my algo), I would not really need the FIFO to work but stay completely synchronous. Since the BMI270 implementation in zephyr is kind of rudimentary not fulfilling all my needs, I am directly reading and writing registers (single byte or multibyte) using the lower level functionality given in the zephyr driver source (see below).
Now I am at the point, that I can setup FIFO mode: I have headerless dataframes of 12 byte (acc and gyr), so the FIFO length nicely goes up in steps of 12... when the FIFO is full, interrupt 2 is triggered fine and the length stays the same from then on.
BUT: no matter when and with how many bytes I try to read the FIFO data gegister - I get strange results that seem to have nothing to do with the sensor data... but I do not get any error.
=> I have seen, that there are some variants of the configuration file (I am using the "basic" version, implemented in the zephyr driver so far).
Is the version I use made for FIFO use? It looks like there is a different one used at least in some (but seemingly not all) BMI270 samples published by BST.
=> Is there a "low level" sample for reading from the FIFO Data register via SPI using e.g. the Bosch Sensortech code in bmi270_spi.c
static int bmi270_reg_read_spi(const union bmi270_bus *bus, uint8_t start, uint8_t *data, uint16_t len)
The method implemented there is what I use successfully for all other register reads so far...
=> Is the method for reading Data from the FIFO data register different from other registers?
Thank you very much for any help on this!
mshape