nrf52 + BMI160 on I2c

[parvathi]

Hi,

I have a peculiar problem problem with BMI160 and nrf52. BMI160 is connected to nrf52 via pins 12 and 13. I am using peripheral/twi_sensor example. After configuring it via I2c I am able to read the chip ID of 0x1d , but the chip does not go to normal mode and the accelerometer value always return zero. Do you see any issues with the below code. Kindly help.

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#include

#include "boards.h"

#include "app_util_platform.h"

#include "app_error.h"

#include "nrf_drv_twi.h"

#include "nrf_delay.h"

#include "nrf_log.h"

#include "nrf_log_ctrl.h"

#include "nrf_log_default_backends.h"

#include "bmi160.h"

/* TWI instance ID. */

#define TWI_INSTANCE_ID 0

struct bmi160_dev sensor;

struct bmi160_sensor_data accel;

struct bmi160_sensor_data gyro;

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#include 
#include "boards.h"
#include "app_util_platform.h"
#include "app_error.h"
#include "nrf_drv_twi.h"
#include "nrf_delay.h"


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

#include "bmi160.h"

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

struct bmi160_dev sensor;
struct bmi160_sensor_data accel;
struct bmi160_sensor_data gyro;

int8_t rslt = BMI160_OK;

/* Mode for LM75B. */
#define NORMAL_MODE 0U

/* Indicates if operation on TWI has ended. */
static volatile bool m_xfer_done = false;

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

/* Buffer for samples read from temperature sensor. */
static uint8_t m_sample;



/**
 * @brief UART initialization.
 */
void twi_init (void)
{
   // NRF_LOG_INFO("in twi\r\n");
    ret_code_t err_code;

    const nrf_drv_twi_config_t twi_lm75b_config = {
       .scl                = 12,//ARDUINO_SCL_PIN,
       .sda                = 11,//ARDUINO_SDA_PIN,
       .frequency          = NRF_DRV_TWI_FREQ_100K,
       .interrupt_priority = APP_IRQ_PRIORITY_HIGH,
       .clear_bus_init     = false
    };

    err_code = nrf_drv_twi_init(&m_twi, &twi_lm75b_config, NULL, NULL);
    APP_ERROR_CHECK(err_code);
       if (NRF_SUCCESS == err_code)
	{
		nrf_drv_twi_enable(&m_twi);
		NRF_LOG_INFO("TWI init success...");	
	}
nrf_delay_ms(5);
}

int8_t Acc_i2c_Write(uint8_t dev_id, uint8_t reg_addr, uint8_t *reg_data, uint16_t len)
{

      //  NRF_LOG_INFO("WRITE: dev_id: %x reg_addr: %x reg_data: %x len: %i\n", dev_id, reg_addr, *reg_data, len);
	int8_t rslt = 0;
	uint8_t data[len + 1];
	data[0] = reg_addr;
	for (uint16_t i = 0; i < len; i++) {
		data[i + 1] = reg_data[i];
	}
	
	rslt = nrf_drv_twi_tx(&m_twi, dev_id, reg_data, len + 1, false);
	APP_ERROR_CHECK(rslt);
        return rslt;
  
}


int8_t Acc_i2c_Read(uint8_t dev_id, uint8_t reg_addr, uint8_t *reg_data, uint16_t len)
{
	int8_t rslt = 0;
     //   NRF_LOG_INFO("READ: dev_id: %x reg_addr: %x len: %i\n", dev_id, reg_addr, len);
	rslt = nrf_drv_twi_tx(&m_twi, dev_id, ®_addr, 1, false);
        APP_ERROR_CHECK(rslt);

	if (rslt == 0)
	{
		rslt = nrf_drv_twi_rx(&m_twi, dev_id, reg_data, len);
	}
     //   NRF_LOG_INFO("READ: %x",*reg_data);
	return rslt;
}

void Acc_delay_ms(uint32_t period)
{ 
	
/*if (period==NULL){
period = 1;
}// delay time*/
	
  nrf_delay_ms( period ) ;
}


void BMI160_init (void)
{
    sensor.id = 0x69,//BMI160_I2C_ADDR;         //0x69
    sensor.interface = BMI160_I2C_INTF;  //0x00
    sensor.read = &Acc_i2c_Read;
    sensor.write = &Acc_i2c_Write;
    sensor.delay_ms = &Acc_delay_ms;

    rslt = bmi160_init(&sensor);
    APP_ERROR_CHECK(rslt);

    if(rslt == BMI160_OK){
    NRF_LOG_INFO("BMI160 Initialized...");
    } else {
    NRF_LOG_INFO("BMI160 not Initialized...");
    }
    //NRF_LOG_FLUSH();

    sensor.accel_cfg.odr = BMI160_ACCEL_ODR_100HZ;//BMI160_ACCEL_ODR_1600HZ;
    sensor.accel_cfg.range = BMI160_ACCEL_RANGE_2G;
    sensor.accel_cfg.bw = BMI160_ACCEL_BW_NORMAL_AVG4;
    sensor.accel_cfg.power = BMI160_ACCEL_NORMAL_MODE;

    rslt = bmi160_set_sens_conf(&sensor);
    APP_ERROR_CHECK(rslt);

     if(rslt == BMI160_OK){
    NRF_LOG_INFO("sensor Configured...");
    } else {
    NRF_LOG_INFO("sensor not Configured...");
    }

/* Select the power mode */
sensor.accel_cfg.power = BMI160_ACCEL_NORMAL_MODE;


/*  Set the Power mode  */
rslt = bmi160_set_power_mode(&sensor);
     if(rslt == BMI160_OK){
    NRF_LOG_INFO("normal Configured...");
    } else {
    NRF_LOG_INFO("normal not Configured...");
    }
    //NRF_LOG_FLUSH();
}

static void read_sensor_data()
{
      m_xfer_done = false;
      accel.x = 1;
      bmi160_get_sensor_data(BMI160_ACCEL_SEL, &accel, NULL, &sensor);
      NRF_LOG_INFO("DataX:%d", accel.x);
      NRF_LOG_INFO("DataY:%d", accel.y);
      NRF_LOG_INFO("DataZ:%d", accel.z);

}


#if 1
int main(void)
{

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

    NRF_LOG_INFO("\r\nBMI160 get started.\n");
    NRF_LOG_FLUSH();
    Acc_delay_ms(100);

    twi_init();
    Acc_delay_ms(50);
   //LM75B_set_mode();
    BMI160_init();
    Acc_delay_ms(1000);


    uint8_t reg_addr = BMI160_CHIP_ID_ADDR;
    uint8_t data;
    uint16_t len = 1;
    rslt = bmi160_get_regs(reg_addr, &data, len, &sensor);
    NRF_LOG_INFO("chip addr: %x \r\n",data);

/* Select the power mode */
sensor.accel_cfg.power = BMI160_ACCEL_NORMAL_MODE;


/*  Set the Power mode  */
rslt = bmi160_set_power_mode(&sensor);
     if(rslt == BMI160_OK){
    NRF_LOG_INFO("normal Configured...");
    } else {
    NRF_LOG_INFO("normal not Configured...");
    }
    Acc_delay_ms(1000);
    uint8_t reg_addr1 = BMI160_PMU_STATUS_ADDR;
    data = 0xff;
    len = 1;
    rslt = bmi160_get_regs(reg_addr1, &data, len, &sensor);
    NRF_LOG_INFO("mode: %x \r\n",data);
    uint8_t cmd =0x11;
    uint8_t *cmd1=&cmd;

    while(true)
    {
    /*  Set the Power mode  */

        Acc_delay_ms(1000);
  
        read_sensor_data();
        NRF_LOG_FLUSH();
    }
}

[Jørgen Holmefjord]

Hi,

Can you post the definitions of bmi160_set_power_mode() and bmi160_get_regs()?

Can you provide a logic trace of the TWI-bus communication between the nRF and the sensor?

I see that in Acc_i2c_Read(), you set the no_stop parameter to false, have you checked that this is correct according to the communication protocol of the sensor, described in the datasheet? Typically, this kind of sensors does not expect a stop between writing the control byte and reading the response, rather a repeated start condition.

Best regards,
Jørgen

[parvathi]

Jorgen, Thank  you for your reply. 

I could resolve this issue. There was a bug in the code " rslt = nrf_drv_twi_tx(&m_twi, dev_id, reg_data, len + 1, false);" It should be "data" here and not "reg_data". Thankyou for your help