Error reading BME680 with a NORDIC DK

[arnaud]

Hello everyone, I have an error when I read BME680 the values never change and humidity is at 100 % but the read fonction return a zero which means everything ok. I don't know why it's not working I guess it's in my read and write functions but I don't find my mistake.

Here is my code : thank you for your time and have a good day.

NB : NRF_LOG is used for display like Serial.print in arduino. 

err = nrf_drv_twi_rx(&m_twi, dev_id, tampon, len); : this function is like the Wire.request(tampon, len ) on arduino.

nrf_drv_twi_tx(&m_twi, dev_id, reg, len+1, false); : this function is like the Wire.begintransmission(dev_id) then wire.write(reg);

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 *    Semiconductor ASA integrated circuit in a product or a software update for
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 *    Nordic Semiconductor ASA integrated circuit.
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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_delay.h"

#include "nrf_log.h"
#include "nrf_log_ctrl.h"
#include "nrf_log_default_backends.h"
#include "bme680.h"

struct bme680_dev gas_sensor;
int8_t rslt = BME680_OK;

/* TWI instance ID. */
#if TWI0_ENABLED
#define TWI_INSTANCE_ID     0
#elif TWI1_ENABLED
#define TWI_INSTANCE_ID     1
#endif

int compteur = 0;

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

int8_t user_i2c_read (uint8_t dev_id, uint8_t reg_addr, uint8_t *data, uint16_t len)
{
  ret_code_t err;
  uint8_t tampon[30]={0};
  NRF_LOG_INFO("read");
  NRF_LOG_FLUSH();

  int size=0, result = 0, j=0;
  uint8_t reg[1]={reg_addr};
  nrf_drv_twi_tx(&m_twi, dev_id, reg, 1,false);
  err = nrf_drv_twi_rx(&m_twi, dev_id, tampon, len);
  NRF_LOG_INFO("read : len %d :",len);
  NRF_LOG_FLUSH();
  if(err==0)
   {size=1;
 for(int i = 0 ;i<30;i++)
  {
    if(tampon[i]!=0) size=i+1;
//    NRF_LOG_INFO("tampon : %d",tampon[i]);
//      NRF_LOG_FLUSH();
   }
   }
   else
   size=0;
//       NRF_LOG_INFO("len %d",len);
//    NRF_LOG_FLUSH();
//    NRF_LOG_INFO("size %d",size);
//    NRF_LOG_FLUSH();

if(size >14  ) size=len;
NRF_LOG_INFO("read : wire.available %d :",size);
  NRF_LOG_FLUSH();
  if(len<=size)
    { for (int i=0;i<len;i++)
    {
      data[i]=tampon[i];

      NRF_LOG_INFO("%d",data[i]);
      NRF_LOG_FLUSH();
    }

     }
   else
   {result=5;}

   
 
return result;
 
}

/**
 * Write the content into the register targeted register for a specified device
 *
 * Parameter :
 *    dev_id : the I2C adress of the device
 *    reg_addr : the adresse of the targeted register
 *    *data : pointer to the data to write
 *    len : number in byte of the data
 *
 * Return:  Error code
 */

int8_t user_i2c_write (uint8_t dev_id, uint8_t reg_addr, uint8_t *data, uint16_t len)
{
NRF_LOG_INFO("write");
  NRF_LOG_FLUSH();
    int result=0;
  uint8_t reg[]={reg_addr,*data};
  nrf_drv_twi_tx(&m_twi, dev_id, reg, len+1, false);
  return result;

}

/**
 * function to wait the time
 *
 * Parameter :
 *    period : time that will be waited in millisecond
 */
void user_delay_ms (uint32_t period)
{
  nrf_delay_ms(period);
}

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

    const nrf_drv_twi_config_t twi_config = {
       .scl                = ARDUINO_13_PIN ,
       .sda                = ARDUINO_12_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_config, NULL, NULL);
    APP_ERROR_CHECK(err_code);

    nrf_drv_twi_enable(&m_twi);
}

/**
 * @brief Function for initialising bme 680 in forced mode.
 */
void init_bme (void)
{
uint8_t set_required_settings;

    /* Set the temperature, pressure and humidity settings */
    gas_sensor.tph_sett.os_hum = BME680_OS_2X;
    gas_sensor.tph_sett.os_pres = BME680_OS_4X;
    gas_sensor.tph_sett.os_temp = BME680_OS_8X;
    gas_sensor.tph_sett.filter = BME680_FILTER_SIZE_3;

    /* Set the remaining gas sensor settings and link the heating profile */
    gas_sensor.gas_sett.run_gas = BME680_ENABLE_GAS_MEAS;
    /* Create a ramp heat waveform in 3 steps */
    gas_sensor.gas_sett.heatr_temp = 320; /* degree Celsius */
    gas_sensor.gas_sett.heatr_dur = 150; /* milliseconds */

    /* Select the power mode */
    /* Must be set before writing the sensor configuration */
    gas_sensor.power_mode = BME680_FORCED_MODE;

    /* Set the required sensor settings needed */
    set_required_settings = BME680_OST_SEL | BME680_OSP_SEL | BME680_OSH_SEL | BME680_FILTER_SEL
        | BME680_GAS_SENSOR_SEL;

    /* Set the desired sensor configuration */
    rslt = bme680_set_sensor_settings(set_required_settings,&gas_sensor);

    /* Set the power mode */
    rslt = bme680_set_sensor_mode(&gas_sensor);
}

/**
 * @brief Function for main application entry.
 */
int main(void)
{
    ret_code_t err_code;
 

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

    NRF_LOG_INFO("TWI scanner started.");
    NRF_LOG_FLUSH();
    twi_init();
    gas_sensor.dev_id = BME680_I2C_ADDR_SECONDARY;
    gas_sensor.intf = BME680_I2C_INTF;
    gas_sensor.read = user_i2c_read;
    gas_sensor.write = user_i2c_write;
    gas_sensor.delay_ms = user_delay_ms;
    gas_sensor.amb_temp = 25;
    rslt = bme680_init(&gas_sensor);
    init_bme();
    NRF_LOG_INFO("Rslt : %d",rslt);
    NRF_LOG_FLUSH();
    if(rslt!=0)
    {
    NRF_LOG_INFO("no BME680 detected");
    NRF_LOG_FLUSH();
    while(1);
    }

   
 
    while (true)
    {
        // put your main code here, to run repeatedly:
  uint16_t meas_period;
  bme680_get_profile_dur(&meas_period, &gas_sensor);
 
 
  struct bme680_field_data data;
   
    while(1){
  nrf_delay_ms(meas_period);
  rslt = bme680_get_sensor_data(&data, &gas_sensor);
  NRF_LOG_INFO("RSLT READ %d",rslt);
 NRF_LOG_FLUSH();
   NRF_LOG_INFO("%d",data.temperature);
 NRF_LOG_FLUSH();
 NRF_LOG_ERROR( "Température :  " NRF_LOG_FLOAT_MARKER "\r\n", NRF_LOG_FLOAT(data.temperature /100.0));
 NRF_LOG_FLUSH();
 NRF_LOG_ERROR( "Pression :  " NRF_LOG_FLOAT_MARKER "\r\n", NRF_LOG_FLOAT(data.pressure /100.0));
 NRF_LOG_FLUSH();
 NRF_LOG_ERROR( "Humidity :  " NRF_LOG_FLOAT_MARKER "\r\n", NRF_LOG_FLOAT(data.humidity /1000.0));
 NRF_LOG_FLUSH();
  /* Avoid using measurements from an unstable heating setup */
 
  if (data.status & BME680_GASM_VALID_MSK)
  {
    NRF_LOG_INFO("G: ");
    NRF_LOG_INFO("%d",data.gas_resistance);
    NRF_LOG_INFO("Kohms");
    NRF_LOG_FLUSH();
  }

  /* Trigger the next measurement if you would like to read data out continuously */
  if (gas_sensor.power_mode == BME680_FORCED_MODE) {
    rslt = bme680_set_sensor_mode(&gas_sensor);
    }
 while(1);
    }
      
      
    }
}

/** @} */

[Vincent]

I saw the following value in your log:

<info> app: read : reg addr : 116
<info> app: read : len 1 :
<info> app: read : wire.available 1 :
<info> app: 0

<info> app: read : reg addr : 114
<info> app: read : len 1 :
<info> app: read : wire.available 1 :
<info> app: 0

If my understanding is correct,  it means the register 0x72 and 0x74 are both read as 0.  this means the temperature, pressure and humidity measurement are skipped.  it is not match the values in the code you written here. 

I will suggest you check the interface write function (especially burst write) again.  you can try to write into register and read back to confirm it. 

[arnaud]

I thing the write function is working because I write with set_reg and then read with get_reg and the value was correct. I don't know why the value of the registers are 0. Here is the serial of a third MCU which read the data on the serial bus at the Sensor address : You cand find in attachement the serial of this MCU. There are small difference between Nordic and arduino ? could it be the error ? 

Thank you. 

[Vincent]

If you already verified the register value after write to it and it is match the value you written.

Then i will suggest you to check VDD / VDDIO line of sensor.   Only power on reset can reset the register value to 0 if there is no SW reset or another register write happen. 

I do see a bit difference in your provided log,  but  i can't make quick judge if it is the root cause with those screen shots.

[arnaud]

I added these lines before enter in the loop :

uint8_t dat[1]={140};
uint8_t reg[1]={0x74};
uint8_t rega[1]={0x72};
bme680_set_regs(reg, dat, 1, &gas_sensor);
bme680_set_regs(rega, dat, 1, &gas_sensor); 

And now the sensor works. 

[Vincent · Accepted solution]

I'm glad to see the sensor is working. 

But the register 0x72 and 0x74 should be written in function bme680_set_sensor_settings which is already in your init_bme function. 

looks like the execution of this function have some issue.

maybe you can look into the function to find the root cause.