Nrf9160 + AD74413R spi problem with write/read

[mikhail.maryankou]

We have AD74413R and we try send 32-bits frame size using spi interface and try read results, but it return always zero or 0xff bit. Maybe spi interface nrf9160 cannot work with 32-bits frame?
Link - https://www.analog.com/media/en/technical-documentation/data-sheets/AD74413R.pdf (51 page).

[Martin Lesund]

Hi Mikhail,

Please check out the SPI peripheral documentation for the nRF9160: https://infocenter.nordicsemi.com/index.jsp?topic=%2Fps_nrf9160%2Fspim.html&cp=2_0_0_5_12

I do see why that should not work. I would like to know more about your implementation instead. 
Have you checked with a logic analyzor that it is actually behaving correctly?

[mikhail.maryankou]

We don't have logic analyzor :) It's hardcore develop, but between transactions => amperage from 0.04 to 0.05A

#define LOG_LEVEL CONFIG_LOG_DEFAULT_LEVEL
#include <logging/log.h>
LOG_MODULE_REGISTER(main);
#include <zephyr.h>
#include <string.h>
#include <sys/printk.h>
#include <stdio.h>
#include <drivers/gpio.h>
#include <drivers/spi.h>

#define STACK_SIZE 512
u8_t buffer_tx[] = {0x41, 0x01, 0x46, 0xFF};//{0x46, 0x00, 0x00, 0xFF};
#define BUF_SIZE sizeof(buffer_tx)
u8_t buffer_rx[BUF_SIZE] = {};

u8_t buffer2_tx[] = {0x00, 0x00, 0x00, 0xFF};
#define BUF2_SIZE  sizeof(buffer2_tx)
u8_t buffer2_rx[BUF2_SIZE] = {};

#define PIN_3_3_ON 25
#define PIN_3_3_PER_ON 24
#define PIN_BAT_ON 22

#define SPI_CS NULL
#define CS_CTRL_GPIO_DRV_NAME ""

#define SPI_DRV_NAME	"SPI_3"
#define SPI_SLAVE	0
#define SLOW_FREQ	500000
#define FAST_FREQ	16000000

#define CS_CTRL_GPIO_PIN 28
static struct device *gpio;
static struct device *spi;

struct spi_config spi_cfg = {
	.frequency = SLOW_FREQ,
#if CONFIG_SPI_LOOPBACK_MODE_LOOP
	.operation = SPI_OP_MODE_MASTER | SPI_MODE_CPOL | SPI_MODE_LOOP |
#else
	.operation = SPI_OP_MODE_MASTER | SPI_MODE_CPOL |
#endif
	SPI_MODE_CPHA | SPI_WORD_SET(8) | SPI_LINES_SINGLE,
	.slave = SPI_SLAVE,
	.cs = SPI_CS,
};

struct spi_buf tx_buf = {
  .buf = buffer_tx,
  .len = sizeof(buffer_tx),
};
const struct spi_buf_set tx = {
  .buffers = &tx_buf,
  .count = 1
};

struct spi_buf rx_buf = {
  .buf = buffer_rx,
  .len = sizeof(buffer_rx),
};
const struct spi_buf_set rx = {
  .buffers = &rx_buf,
  .count = 1
};

int main()
{
  int err;

  gpio = device_get_binding("GPIO_0");
  spi = device_get_binding(SPI_DRV_NAME);

  err = gpio_pin_configure(gpio, PIN_3_3_ON, GPIO_DIR_OUT);
  if (err == 0) 
  {
    err = gpio_pin_write(gpio, PIN_3_3_ON, 1);
    LOG_INF("err %d", err);
  }
  err = gpio_pin_configure(gpio, PIN_3_3_PER_ON, GPIO_DIR_OUT);
  if (err == 0) 
  {
    err = gpio_pin_write(gpio, PIN_3_3_PER_ON, 1);
    LOG_INF("err %d", err);
  }

  err = gpio_pin_configure(gpio, PIN_BAT_ON, GPIO_DIR_OUT);
  if (err == 0) 
  {
      err = gpio_pin_write(gpio, PIN_BAT_ON, 1);
      LOG_INF("err %d", err);
  }

  err = gpio_pin_configure(gpio, CS_CTRL_GPIO_PIN, GPIO_DIR_OUT);
  if (err == 0) 
  {
      gpio_pin_write(gpio, CS_CTRL_GPIO_PIN, 1); //PULL CS HIGH
  }


  //1
  buffer_tx[3] = crc8_ccitt(0, buffer_tx, 3);
  buffer2_tx[3] = crc8_ccitt(0, buffer2_tx, 3);

  int ret;
  
  LOG_INF("Start complete multiple");
  ret = gpio_pin_write(gpio, CS_CTRL_GPIO_PIN, 0); //PULL CS LOW
  ret = spi_transceive(spi, &spi_cfg, &tx, NULL);
  if (ret) 
  {
      LOG_ERR("Code %d", ret);
      return ret;
  }
  ret = gpio_pin_write(gpio, CS_CTRL_GPIO_PIN, 1); //PULL CS HIGH


  //2
  tx_buf.buf = buffer2_tx;
  tx_buf.len = sizeof(buffer2_tx);
  
  ret = gpio_pin_write(gpio, CS_CTRL_GPIO_PIN, 0); //PULL CS LOW
  ret = spi_transceive(spi, &spi_cfg, &tx, &rx);
  if (ret) 
  {
      LOG_ERR("Code %d", ret);
      return ret;
  }
  ret = gpio_pin_write(gpio, CS_CTRL_GPIO_PIN, 1); //PULL CS HIGH

  rx_buf.buf = buffer2_rx;
  rx_buf.len = sizeof(buffer2_rx);

  ret = gpio_pin_write(gpio, CS_CTRL_GPIO_PIN, 0); //PULL CS LOW
  ret = spi_transceive(spi, &spi_cfg, &tx, &rx);
  if (ret) 
  {
      LOG_ERR("Code %d", ret);
      return ret;
  }
  ret = gpio_pin_write(gpio, CS_CTRL_GPIO_PIN, 1); //PULL CS HIGH

  if (memcmp(buffer_tx, buffer_rx, BUF_SIZE)) 
  {
      return -1;
  }

  if (memcmp(buffer2_tx, buffer2_rx, BUF2_SIZE)) 
  {
      return -1;
  }
  
  LOG_INF("Passed");
  return 0;
}

[Martin Lesund]

Hi Mikhail,
Without a Logic analyzer it is difficult to verify correct behavior of the SPI interface.
I strongly recommend getting a hold of such equipment.