nRF52832 cannot stop adxl362's spi

[bardia3000]

Hello, I tried to work with nRF52832 to read adxl362 registers, Here is my function to read all 3 received bytes from adxl362 (according to datasheets, the last byte must have the right value):

long ADXL362_regRead(uint8_t Reg_address) {
  uint8_t SPI_TX_Buff[2] = {0x0B, Reg_address};
  uint8_t SPI_RX_Buff[3] = {0, 0, 0};
  nrf_gpio_pin_clear(SPI_ACC_SS_PIN);
  spi_xfer_done = false;
  nrf_drv_spi_transfer(&spi, SPI_TX_Buff, 2, SPI_RX_Buff, 3);
  while (!spi_xfer_done) {
    __WFE();
  }
  nrf_gpio_pin_set(SPI_ACC_SS_PIN);
  return ((SPI_RX_Buff[2]) | (SPI_RX_Buff[1] << 8) | (SPI_RX_Buff[0] << 16));
}

every time I run this code to read a specific register repeatedly, for example register 0x00, which is 0xAD, the nRF52832 reads 0xAD and writes all other registers start from address 0x00 to 0x2E. It looks like changing SS pin doesn't stop the ADXL362. What can I do?

[haakonsh]

Take a scope of the SPI lines with a digital analyzer and share it with us.

Also, the first two bytes you receive are not valid for a single register read, so your return value should only be one byte long. 

[bardia3000]

Thanks a lot, I define SPI_ACC_SS_PIN as p0.10, It seems like it is always zero with a digital analyzer! Why is that and what can I do? (I set this pin as an output before)

[haakonsh]

You seem to be controlling the CS pin manually, the driver should handle that. What SDK version are you using?

[bardia3000]

Actually there are some other chips on the SPI bus, So I set the spi_config.ss_pin as NRF_DRV_SPI_PIN_NOT_USED and control CS pin manually. Also I use SDK version 16.0.0. Can this happen because of NFC2 pin which is at the same pin as P0.10?

[haakonsh]

bardia3000 said:

Actually there are some other chips on the SPI bus, So I set the spi_config.ss_pin as NRF_DRV_SPI_PIN_NOT_USED and control CS pin manually.

 Fair enough.
 

bardia3000 said:

Also I use SDK version 16.0.0. Can this happen because of NFC2 pin which is at the same pin as P0.10?

Not unless it's configured as an NFC pin and not a GPIO. To use these pins as GPIO's you need to set the preprocessor definition CONFIG_NFCT_PINS_AS_GPIOS. 


You should always scope your communication lines whenever there's a problem, it will help immensely in debugging the issue.