Unable to use TWI on nrf52840

Question

Hi

I am trying to use the TWI on nrf52840 but i am unable to get it to work. its getting stuck somewhere. I dont have a logic analyzer so i am unable to check if the signal are coming or not. I am able to use the I2C with apache mynewt so i dont think its the hardware problem. i have doubled checked the pin assignments for SCL and SDA as well. I have attached the code. Please help me out.

Output on the terminal:

<info> app: TWI scanner started
<info> app: Function return code: NRF_SUCCESS
<info> app: after twi_init

sdk_config.h

Fullscreen main.c Download

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/** @file
 * @defgroup tw_scanner main.c
 * @{
 * @ingroup nrf_twi_example
 * @brief TWI Sensor Example main file.
 *
 * This file contains the source code for a sample application using TWI.
 *
 */

#include <stdio.h>
#include "boards.h"
#include "app_util_platform.h"
#include "app_error.h"
#include "nrf_drv_twi.h"



#include "nrf_log.h"
#include "nrf_log_ctrl.h"
#include "nrf_log_default_backends.h"

/* TWI instance ID. */
#define TWI0_ENABLED 1
#define TWI_INSTANCE_ID     0

#define MPU9250_ADDRESS 0x68
#define WHO_AM_I_MPU9250 0x75 // Should return 0x71
#define CORRECT_RETURN 0x71

/* TWI instance. */
static const nrf_drv_twi_t m_twi = NRF_DRV_TWI_INSTANCE(TWI_INSTANCE_ID);



/**
 * @brief TWI initialization.
 */
void twi_init (void)
{
    ret_code_t err_code;

    const nrf_drv_twi_config_t twi_config = {
       .scl                = I2C_0_PIN_SCL,
       .sda                = I2C_0_PIN_SDA,
       .frequency          = I2C_0_FREQ_KHZ,
       .interrupt_priority = APP_IRQ_PRIORITY_HIGH,
       .clear_bus_init     = false
    };

    err_code = nrf_drv_twi_init(&m_twi, &twi_config, NULL, NULL);
    
    char const * p_desc = nrf_strerror_find(err_code);
    if (p_desc == NULL)
    {
        /* No human readable form found */
        NRF_LOG_INFO("Function return code: UNKNOWN (%x)", err_code);
    }
    else
    {
        /* Nice - mnemonic like - human readable form found */
        NRF_LOG_INFO("Function return code: %s", p_desc);
    }
     
    APP_ERROR_CHECK(err_code);
    nrf_drv_twi_enable(&m_twi);

}

/*
 * function to read sensor registers.
*/
ret_code_t read_register(nrf_drv_twi_t twi_instance, uint8_t device_addr, uint8_t register_addr, uint8_t *p_data, uint8_t bytes, bool no_stop)
{
  ret_code_t err_code;

  err_code = nrf_drv_twi_tx(&twi_instance, device_addr, &register_addr, 1, no_stop);
  APP_ERROR_CHECK(err_code);

  if(err_code != NRF_SUCCESS) {
    return err_code;
  }

  err_code = nrf_drv_twi_rx(&twi_instance, device_addr, p_data, bytes);
  return err_code;
}


/**
 * @brief Function for main application entry.
 */
int main(void)
{
    ret_code_t err_code;
    //uint8_t address;
    uint8_t sample_data;
    bool detected_device = false;

    APP_ERROR_CHECK(NRF_LOG_INIT(NULL));
    NRF_LOG_DEFAULT_BACKENDS_INIT();

    NRF_LOG_INFO("TWI scanner started");
    NRF_LOG_FLUSH();
    twi_init();
    NRF_LOG_INFO("after twi_init");
	NRF_LOG_FLUSH();  


	err_code = read_register(m_twi, MPU9250_ADDRESS, WHO_AM_I_MPU9250, &sample_data, sizeof(sample_data), 0);

	char const * p_desc = nrf_strerror_find(err_code);
	if (p_desc == NULL)
	{
		/* No human readable form found */
		NRF_LOG_INFO("Function read_register code: UNKNOWN (%x)", err_code);
	}
	else
	{
		/* Nice - mnemonic like - human readable form found */
		NRF_LOG_INFO("Function read_register code: %s", p_desc);
	}
	NRF_LOG_FLUSH();
	
	if (err_code == NRF_SUCCESS)
	{
		detected_device = true;
		NRF_LOG_INFO("should be 0x71 but is 0x%02X", sample_data);
	}else{
		NRF_LOG_INFO("Failed!\n");
	}
	NRF_LOG_FLUSH();	
	
	
    if (!detected_device)
    {
        NRF_LOG_INFO("No device was found.");
        NRF_LOG_FLUSH();
    }

    while (true)
    {
        /* Empty loop. */
    }
}

/** @} */

Thanks.