After the soft reset the BMI270 will be back in I2C mode and you'll have to get it to switch back to SPI mode before attempting to read the registers. I ususlly just toggle the CS low for 10ms but you can also perform a "dummy" register read to get it to switch. I also add a small delay after switching before reading the first register to give it time to switch but this isn't documented in the datasheet so I don't know if it's required (but probably a good idea).
... View more