I have the sensor hooked up to a UART on a Pic32 microcontroller. The sensor will send data for several hours and then just stop. The only way to fix the problem is to power cycle the sensor. I have looked at the data lines with an oscilloscope and can see that the pic is requesting data but there is no reply from the sensor. Power cycle just the sensor and it starts working again. Has anyone else had this problem?

Here is the code

void task_dfrobot_sensor(void *pvParameters){

/* skipping some initialization */

while(1)

{

if (DFR_MODE == DFROBOT_SETTING_QA_MODE)

{

vTaskDelayUntil( &pxPreviousWakeTime, 1000 / portTICK_PERIOD_MS);

} else {

vTaskDelay( 600 / portTICK_PERIOD_MS);

}

if (DFR_INTERVAL == 0) { continue; }

switch (ro_state)

{

case RO_INIT:

df_err = _open_driver(&df_handle, uart_num);

df_handle.mode = DFR_MODE;

if (df_err == DFROBOT_SUCCESS)

{

ro_state = RO_MODE;

}

else

{

_send_no_sensor(uart_num);

}

break;

case RO_MODE:

_send_info_msg(uart_num, "RO_MODE state"); /* debug code */

_flush_uart(uart_num);

df_err = DFROBOT_set_mode(&df_handle, DFR_MODE);

if (df_err == DFROBOT_SUCCESS)

{

ro_state = RO_SENS_TYPE;

missed_reading_cnt = 0;

break;

}

else if (df_err == DFROBOT_ERR_TIMEOUT)

{

_send_no_sensor(uart_num);

}

else

{

_send_err(uart_num, df_err);

}

if (_missed_cnt_over_max(&missed_reading_cnt))

{

ro_state = RO_PWR_CYCL_SENS;

}

break;

case RO_SENS_TYPE:

_flush_uart(uart_num);

if (DFR_MODE == DFROBOT_SETTING_ACTIVE_MODE) {

df_err = DFROBOT_read_gas_temp(&df_handle, &gas_type, &gas, &temp);

} else {

df_err = DFROBOT_read_gas(&df_handle, &gas_type, &gas);

}

if (df_err == DFROBOT_SUCCESS)

{

/* different sensors can be set to different intervals */

itrvl_idx = _get_intrvl_indx(gas_type);

ro_state = RO_RUN;

missed_reading_cnt = 0;

break;

}

else if (df_err == DFROBOT_ERR_TIMEOUT)

{

_send_no_sensor(uart_num);

DFROBOT_set_mode(&df_handle, DFR_MODE);

}

else

{

_send_err(uart_num, df_err);

}

if (_missed_cnt_over_max(&missed_reading_cnt))

{

ro_state = RO_PWR_CYCL_SENS;

}

break;

case RO_RUN:

_flush_uart(uart_num);

if (DFR_MODE == DFROBOT_SETTING_ACTIVE_MODE) {

df_err = DFROBOT_read_gas_temp(&df_handle, &gas_type, &gas, &temp);

} else {

df_err = DFROBOT_read_gas(&df_handle, &gas_type, &gas);

}

if (df_err)

{

_send_err(uart_num, df_err);

if (df_err == DFROBOT_ERR_TIMEOUT)

{

_send_no_sensor(uart_num);

}

if (_missed_cnt_over_max(&missed_reading_cnt))

{

ro_state = RO_PWR_CYCL_SENS;

}

break;

} else {

/* Add reading to buffer for median filter */

avg_filter_push_float (&rbuff, gas);

missed_reading_cnt = 0;

}

if ((next_send_time - xTaskGetTickCount()) < DFR_INTERVAL)

{

break;

}

if( !avg_filt_get_median_float(&rbuff, &gas) ) /* filter out any outliers */

{

_send_gas(gas_type, gas);

_check_limits(gas_type, gas);

}

next_send_time = xTaskGetTickCount() + DFR_INTERVAL;

break;

case RO_PWR_CYCL_SENS:

_send_info_msg(uart_num, "STATE - RO_PWR_CYCL_SENS");

_ms_delay(100);

_sens_pwr_cycl(uart_num);

ro_state = RO_MODE;

break;

default:

break;

}

}

}

DFROBOT_ERR DFROBOT_read_gas(DFROBOT_s *handle, int *gas_type, float *gas)

{

DFROBOT_ERR err;

uint8_t read_msg[DFROBOT_BUFF_LEN];

/* if in QA mode then request the reading */

err = _request_gas(handle);

if (err != DFROBOT_SUCCESS)

{

return err;

}

handle->delay(50);

// wait for response

err = _read_and_verify(handle, read_msg, DFROBOT_BUFF_LEN);

if (err != DFROBOT_SUCCESS)

{

return err;

}

// passive response

// 0xFF, 0x86, gas high, gas low, gas type, decimal places, 0, 0, check sum

// check command type

if (read_msg[1] != 0x86)

{

return DFROBOT_ERR_SENSOR;

}

*gas_type = read_msg[4];

float temp;

/* reusing this. temp will get set to 0.0 */

err = _extract_gas_temp(read_msg, gas, &temp);

if (err != DFROBOT_SUCCESS) return err;

return DFROBOT_SUCCESS;

}

STATIC DFROBOT_ERR _request_gas(DFROBOT_s *handle)

{

uint8_t buff[] = {0xFF, 0x01, 0x86, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};

buff[8] = _check_value(buff, DFROBOT_BUFF_LEN);

return _write(handle, buff, DFROBOT_BUFF_LEN);

}

/**

* @brief Takes the full buffer of data returned from the sensor. From this

* the gas values and temperature value are calculated and returned.

*

* Note: the temperature value has not been implemented.

*

* @param buff

* @param gas

* @param temp - always 0.0

* @return STATIC

*/

STATIC DFROBOT_ERR _extract_gas_temp(uint8_t *buff, float *gas, float *temp)

{

uint8_t gas_high = buff[2];

uint8_t gas_low = buff[3];

uint8_t resolution = buff[5];

*gas = _calc_gas(gas_high, gas_low, resolution);

if (*gas == -555.5) /* calc_gas returns this exact value if there was an error */

{

return DFROBOT_ERR_SENSOR;

}

/* have not implemented the temperature calculation */

*temp = 0.0;

return DFROBOT_SUCCESS;

}

STATIC float _calc_gas(uint8_t gas_high, uint8_t gas_low, uint8_t resolution)

{

uint16_t ugas = (gas_high << 8) | gas_low;

float fgas = (float)ugas;

float res = 0.0;

switch (resolution)

{

case DFROBOT_GAS_1:

res = 1.0f;

break;

case DFROBOT_GAS_0_1:

res = 0.1f;

break;

case DFROBOT_GAS_0_01:

res = 0.01;

break;

default:

return -555.5;

break;

}

return fgas * res;

}

/**

* @brief Takes the entire 9 byte buffer and calculates the checksum

*

* @param buff

* @param len

* @return uint8_t checksum

*/

STATIC uint8_t _check_value(uint8_t *buff, int len)

{

int j;

uint8_t tempq = 0;

buff++;

for (j=0; j<(len-3); j++)

{

tempq += *buff;

buff++;

}

return (~tempq) + 1;

}