MPU9250 and nrf52832 / TWI communication issue

Question

Hi,

I have migrate to SDK14.2 the MPU9250 exemple from the peripheral folder in the nrf52-pesky exemples : https://github.com/e27182/nRF52832_pesky https://github.com/e27182/nRF52832_pesky

I have extensively use Martin exemple to understand the read/write TWI routine : https://github.com/Martinsbl/nrf5-mpu-examples

I have integrate ESB communication inside the program and tested with the nrf52DK board.

The goal is to program a Holyiot YJ-18008 nrf52832 /MPU9250 miniature board and transfert the data's to the nrf52dk with ESB.

I have manage to get the inverse working : the a MPU9255 is attach to the nrf52dk and send the IMU data to the 18008 board - no problem.When I install the main program on the 18008 board, and transfert the result to the nrf52DK, the program seems to have problem with the TWI communication. Reading values from the MPU9250 is difficult. It work for a few second but more or less rapidly, give succession of error (cannot read DMP). Sometime the program stop at the MPU initialization phase. I have notice that the TWI communication is very sensitive to delays and other event around the calls. I am using twi manager - see init read write code below. I have tried to just several parameters without success (communication speeds, delays, etc)

I have the following questions :

I saw that the TWI driver have been rewritten in SDK15 /16. Are they more robust ?

Is there and avantage of using easyDMA ?

Is SPI a better option ?

What direction should I take to solve the problem ?

Note that I am not a programmer, and not very familiar with all the C language, SDK and options. I have start this project few weeks ago.

Thanks

 /*
  * The library is not extensively tested and only
  * meant as a simple explanation and for inspiration.
  * NO WARRANTY of ANY KIND is provided.
  */


#if defined MPU_USES_TWI // Use TWI drivers


#define  NRF_LOG_MODULE_NAME nrf_drv_mpu_twi

#include <stdbool.h>
#include <stdint.h>
#include <string.h>
//#include "nrf_drv_twi.h"

#include "app_util_platform.h"
#include "nrf_gpiote.h"
//SL for Twi_scanner
#include "nrf_error.h"  

#include "nrf_twi_mngr.h"

#include "nrf_delay.h"//sl
#include "nrf_drv_mpu2.h"




/* Pins to connect MPU. Pinout is different for nRF51 DK and nRF52 DK
 * and therefore I have added a conditional statement defining different pins
 * for each board. This is only for my own convenience. 
 */

#if defined BOARD_PCA10040
   #define MPU_TWI_SDA_PIN 26 // PCA10040
   #define MPU_TWI_SCL_PIN 27  
 #elif defined BOARD_HOL18008
 #define MPU_TWI_SDA_PIN 11 // HOL18008
 #define MPU_TWI_SCL_PIN 12 
#endif

#define MPU_TWI_BUFFER_SIZE     	14 // 14 byte buffers will suffice to read acceleromter, gyroscope and temperature data in one transmission.
#define MPU_TWI_TIMEOUT 			5000 
#define MPU_ADDRESS     			0x68 
#define MPU_AK89XX_MAGN_ADDRESS     0x0C

//#define TWI_ADDRESSES  127

#define TWI_INSTANCE_ID             0
#define MAX_PENDING_TRANSACTIONS    5


NRF_TWI_MNGR_DEF(m_nrf_twi_mngr, MAX_PENDING_TRANSACTIONS, TWI_INSTANCE_ID);


/**
 * @brief TWI initialization.
 * Just the usual way. Nothing special here
 */
uint32_t nrf_drv_mpu_init(void)
{
    uint32_t err_code;
    
     nrf_drv_twi_config_t const twi_mpu_config = {
       .scl                = MPU_TWI_SCL_PIN,
       .sda                = MPU_TWI_SDA_PIN,
       .frequency          = NRF_TWI_FREQ_400K,     
       .interrupt_priority = APP_IRQ_PRIORITY_HIGH,
       .clear_bus_init     = false
    };
    
  //  err_code = nrf_drv_twi_init(&m_twi_instance, &twi_mpu_config, twi_event_handler, NULL);
    
    err_code = nrf_twi_mngr_init(&m_nrf_twi_mngr, &twi_mpu_config);
    APP_ERROR_CHECK(err_code);
    
    if(err_code != NRF_SUCCESS)
	{
		return err_code;
	}

     NRF_TWI_MNGR_ENABLED;
  
}

// Pesky read and write

uint32_t  nrf_mpu_write(uint8_t slave_addr, uint8_t reg_addr, uint8_t length, uint8_t  * p_data)
{

    ret_code_t err_code;

    uint8_t buffer[length+1];
    buffer[0] = reg_addr;
    memcpy(&buffer[1], p_data, length);


    nrf_twi_mngr_transfer_t const transfers[] = 
    {
     NRF_TWI_MNGR_WRITE(slave_addr, buffer, length + 1, 0)
    };
    
    err_code = nrf_twi_mngr_perform(&m_nrf_twi_mngr, NULL,  transfers, sizeof(transfers) / sizeof(transfers[0]), NULL);

    APP_ERROR_CHECK(err_code);
    
    return 0;
}


uint32_t  nrf_mpu_read(uint8_t slave_addr, uint8_t reg_addr, uint8_t length, uint8_t * data)
 {
    ret_code_t err_code;


    if (length == 0)
        return NRF_SUCCESS;

    

    nrf_twi_mngr_transfer_t const transfers[] =
    {
        NRF_TWI_MNGR_WRITE(slave_addr, &reg_addr, 1, NRF_TWI_MNGR_NO_STOP),      
        NRF_TWI_MNGR_READ(slave_addr, data, length, 0)
    };
      nrf_delay_us(100);   //  to solve ERROR 3  100us
      
   

     err_code = nrf_twi_mngr_perform(&m_nrf_twi_mngr, NULL,  transfers, sizeof(transfers) / sizeof(transfers[0]), NULL);
   ///  nrf_delay_ms(1);

    //APP_ERROR_CHECK(err_code);
    if(err_code != NRF_SUCCESS) return err_code;



   // if (err_code) return -1;

    return 0;
}



#endif // Use TWI drivers

/**
  @}
*/