bq4050 reading fail on smbus

Question

Hello,

I tried to read the value from bq4050 on smbus.

I had good results but I got wrong value randomly as following.

The last marked value is temperature from DAStatus2Reg(0x72). it works well but randomly it works malfunction.

How can I solve this problem? please help me.

<info> app: bms(3:58:9) : 11164 12400 2678
<info> app: bms(3:58:10) : 11165 12400 2678
<info> app: bms(3:58:11) : 11165 12400 -275
<info> app: bms(3:58:12) : 11164 12400 -275
<info> app: bms(3:58:13) : 11165 12400 -275
<info> app: bms(3:58:14) : 11165 12400 -275
<info> app: bms(3:58:15) : 11164 12400 -275
<info> app: bms(3:58:16) : 11164 12400 2678
<info> app: bms(3:58:17) : 11164 12400 2678
<info> app: bms(3:58:18) : 11165 12400 -275
<info> app: bms(3:58:19) : 11165 12400 -275
<info> app: bms(3:58:20) : 11165 12400 -275
<info> app: bms(3:58:21) : 11165 12400 2678
<info> app: bms(3:58:22) : 11164 12400 2678
<info> app: bms(3:58:23) : 11164 12400 2678
<info> app: bms(3:58:24) : 11165 12400 2678
<info> app: bms(3:58:25) : 11165 12400 2678
<info> app: bms(3:58:26) : 11165 12400 2678

Here is read function as following.

void read_BQ4050_data(uint8_t regAddress, uint8_t size)
{
  ret_code_t err_code;
  uint8_t reg[1] = {regAddress};
  uint8_t buf[2] = {0};

  err_code = nrf_drv_twi_tx(&m_twi, BQ4050_WHO_AM_I, reg, sizeof(reg), false);
  APP_ERROR_CHECK(err_code);
  
  twi_done();


  switch(size)
  {
    case 1:
      err_code = nrf_drv_twi_rx(&m_twi, BQ4050_WHO_AM_I, m_buf8, size);
      break;
    
    case 2:
      err_code = nrf_drv_twi_rx(&m_twi, BQ4050_WHO_AM_I, (uint8_t *)m_buf16, size);
      break;

    case 4:
      err_code = nrf_drv_twi_rx(&m_twi, BQ4050_WHO_AM_I, m_buf, size);
      break;

    default:
      err_code = nrf_drv_twi_rx(&m_twi, BQ4050_WHO_AM_I, m_buf, size);
      break;

  }
  
  APP_ERROR_CHECK(err_code);

  twi_done();

  switch(regAddress)
  {
    case StateOfChargeReg:
      m_bms_measurement1->realSOC = (uint8_t)m_buf8[0];
      break;

    case CellVoltageOne:
      m_bms_measurement1->cellV[0] = m_buf16[0]; 
      //err_check_read(&m_bms_measurement1->cellV[0], &pre_cV1, 1);
      break;

    case CellVoltageTwo:
      m_bms_measurement1->cellV[1] = m_buf16[0]; 
      //err_check_read(&m_bms_measurement1->cellV[1], &pre_cV2, 1);
      break;

    case CellVoltageThree:
      m_bms_measurement1->cellV[2] = m_buf16[0]; 
      //err_check_read(&m_bms_measurement1->cellV[2], &pre_cV3, 1);
      break;

    case CellVoltageFour:
      m_bms_measurement1->cellV[3] = m_buf16[0]; 
      //err_check_read(&m_bms_measurement1->cellV[3], &pre_cV4, 1);
      NRF_LOG_INFO("cell V : %d  %d  %d  %d ", m_bms_measurement1->cellV[0], m_bms_measurement1->cellV[1], m_bms_measurement1->cellV[2], m_bms_measurement1->cellV[3]);
      break;

    case CurrentReg:
      m_bms_measurement1->packCurrent = m_buf16[0]; 
      //m_bms_measurement1->packCurrent = 21000;
      //err_check_read(&m_bms_measurement1->cellV[2], &pre_cV3, 1);
      //NRF_LOG_INFO("Pack C : %d", m_bms_measurement1->packCurrent);
      break;

    case VoltageReg:
      m_bms_measurement1->packVoltage = m_buf16[0]; 
      err_check_read(&m_bms_measurement1->packVoltage, &pre_pV, 1);
      //NRF_LOG_INFO("Pack V : %d", m_bms_measurement1->packVoltage);
      break;

    case OperationStatusReg:
      m_status_bq4050->OperationStatus = byte2short(m_buf[1], m_buf[2]); 
      break;

    case ManufacturingStatusReg:
      m_status_bq4050->ManufacturingStatus = byte2short(m_buf[1], m_buf[2]);; 
      break;

    case DAStatus2Reg:
      m_bms_measurement2->temperature[0] = byte2short(m_buf[3], m_buf[4])-KTEMP_PARAM;
      m_bms_measurement2->temperature[1] = byte2short(m_buf[5], m_buf[6])-KTEMP_PARAM;
      m_bms_measurement2->temperature[2] = byte2short(m_buf[7], m_buf[8])-KTEMP_PARAM; 
      m_bms_measurement2->temperature[3] = byte2short(m_buf[9], m_buf[10])-KTEMP_PARAM;
      NRF_LOG_INFO("Pack Temp : %d", m_bms_measurement2->temperature[0]);
      break;
  }
}