ESP32-PaxCounter/src/sds011read.cpp

// routines for fetching data from the SDS011-sensor

// Local logging tag
static const char TAG[] = __FILE__;

#include <sds011read.h>

// UART(2) is unused in this project
#if (HAS_IF482)
#error cannot use IF482 together with SDS011 (both use UART#2)
#endif
static HardwareSerial sdsSerial(2);    // so we use it here
static SDS011 sdsSensor;               // fine dust sensor

// the results of the sensor:
float pm25;              
float pm10;
boolean isSDS011Active;

// init
bool sds011_init()
{
    pm25 = pm10 = 0.0;
    sdsSerial.begin(9600, SERIAL_8N1, ESP_PIN_RX, ESP_PIN_TX);
    sdsSensor.begin (&sdsSerial);
    sdsSensor.contmode(0);              // for safety: no wakeup/sleep by the sensor
    sds011_sleep();                     // we do it by ourselves
    return true;
}
// reading data:
void sds011_loop()
{
    if ( isSDS011Active ) {
        int sdsErrorCode = sdsSensor.read(&pm25, &pm10);
        if (sdsErrorCode) {
            pm25 = pm10 = 0.0;
            ESP_LOGI(TAG, "SDS011 error: %d", sdsErrorCode);
        }
        else {
            ESP_LOGI(TAG, "fine-dust-values: %5.1f,%4.1f", pm10, pm25);
        }
        sds011_sleep();
    }
    return;
}

// putting the SDS-sensor to sleep
void sds011_sleep(void)
{
    sdsSensor.sleep();
    isSDS011Active = false;
}

// start the SDS-sensor
// needs 30 seconds for warming up
void sds011_wakeup()
{
    if ( !isSDS011Active ) {
        sdsSensor.wakeup();
        isSDS011Active = true;
    }
}