SDS011.cpp

// SDS011 dust sensor PM2.5 and PM10
// ---------------------
//
// By R. Zschiegner (rz@madavi.de)
// April 2016
//
// Documentation:
//		- The iNovaFitness SDS011 datasheet
// Modified By Shachindra for Wake and Sleep Functionality
// June 12, 2019

#include "SDS011.h"

static const byte SLEEPCMD[19] = {
	0xAA,	// head
	0xB4,	// command id
	0x06,	// data byte 1
	0x01,	// data byte 2 (set mode)
	0x00,	// data byte 3 (sleep)
	0x00,	// data byte 4
	0x00,	// data byte 5
	0x00,	// data byte 6
	0x00,	// data byte 7
	0x00,	// data byte 8
	0x00,	// data byte 9
	0x00,	// data byte 10
	0x00,	// data byte 11
	0x00,	// data byte 12
	0x00,	// data byte 13
	0xFF,	// data byte 14 (device id byte 1)
	0xFF,	// data byte 15 (device id byte 2)
	0x05,	// checksum
	0xAB	// tail
};

static const byte WAKECMD[19] = {
	0xAA,	// head
	0xB4,	// command id
	0x06,	// data byte 1
	0x01,	// data byte 2 (set mode)
	0x01,	// data byte 3 (wake up)
	0x00,	// data byte 4
	0x00,	// data byte 5
	0x00,	// data byte 6
	0x00,	// data byte 7
	0x00,	// data byte 8
	0x00,	// data byte 9
	0x00,	// data byte 10
	0x00,	// data byte 11
	0x00,	// data byte 12
	0x00,	// data byte 13
	0xFF,	// data byte 14 (device id byte 1)
	0xFF,	// data byte 15 (device id byte 2)
	0x06,	// checksum
	0xAB	// tail
};

static const byte MODECMD[19] = {
0xAA,  // head
0xB4,  // command id
0x08,  // data byte 1
0x01,  // data byte 2 (set mode)
0x00,  // data byte 3 (0 for continuous, 1-30 for 1-30 min delay between turns on)
0x00,  // data byte 4
0x00,  // data byte 5
0x00,  // data byte 6
0x00,  // data byte 7
0x00,  // data byte 8
0x00,  // data byte 9
0x00,  // data byte 10
0x00,  // data byte 11
0x00,  // data byte 12
0x00,  // data byte 13
0xFF,  // data byte 14 (device id byte 1)
0xFF,  // data byte 15 (device id byte 2)
0x07,  // checksum: 07 for 0x00, 08 for 0x01 and so on
0xAB   // tail
};

SDS011::SDS011(void) {

}

// --------------------------------------------------------
// SDS011:read
// --------------------------------------------------------
int SDS011::read(float *p25, float *p10) {
	byte buffer;
	int value;
	int len = 0;
	int pm10_serial = 0;
	int pm25_serial = 0;
	int checksum_is;
	int checksum_ok = 0;
	int error = 1;
	while ((sds_data->available() > 0) && (sds_data->available() >= (10-len))) {
		buffer = sds_data->read();
		value = int(buffer);
		switch (len) {
			case (0): if (value != 170) { len = -1; }; break;
			case (1): if (value != 192) { len = -1; }; break;
			case (2): pm25_serial = value; checksum_is = value; break;
			case (3): pm25_serial += (value << 8); checksum_is += value; break;
			case (4): pm10_serial = value; checksum_is += value; break;
			case (5): pm10_serial += (value << 8); checksum_is += value; break;
			case (6): checksum_is += value; break;
			case (7): checksum_is += value; break;
			case (8): if (value == (checksum_is % 256)) { checksum_ok = 1; } else { len = -1; }; break;
			case (9): if (value != 171) { len = -1; }; break;
		}
		len++;
		if (len == 10 && checksum_ok == 1) {
			*p10 = (float)pm10_serial/10.0;
			*p25 = (float)pm25_serial/10.0;
			len = 0; checksum_ok = 0; pm10_serial = 0.0; pm25_serial = 0.0; checksum_is = 0;
			error = 0;
		}
		yield();
	}
	return error;
}

// --------------------------------------------------------
// SDS011:sleep
// --------------------------------------------------------
void SDS011::sleep() {
	for (uint8_t i = 0; i < 19; i++) {
		sds_data->write(SLEEPCMD[i]);
	}
	sds_data->flush();
	while (sds_data->available() > 0) {
		sds_data->read();
	}
}

// --------------------------------------------------------
// SDS011:wakeup
// --------------------------------------------------------
void SDS011::wakeup() {
	for (uint8_t i = 0; i < 19; i++) {
		sds_data->write(WAKECMD[i]);
	}
	sds_data->flush();
	while (sds_data->available() > 0) {
		sds_data->read();
	}
}

// --------------------------------------------------------
// SDS011:workmode
// --------------------------------------------------------
void SDS011::workmode(byte mode) {
	byte cs = 7 + mode; // checksum: 07 for 0x00, 08 for 0x01 and so on
	for (uint8_t i = 0; i < 19; i++) {
		if (i == 4) {
			sds_data->write(mode);
		}
		else if (i == 17){
			sds_data->write(cs);
		}
		else{
			sds_data->write(MODECMD[i]);
		}
	}
	sds_data->flush();
	while (sds_data->available() > 0) {
		sds_data->read();
	}
}

#ifndef ESP32
void SDS011::begin(uint8_t pin_rx, uint8_t pin_tx) {
	_pin_rx = pin_rx;
	_pin_tx = pin_tx;

	SoftwareSerial *softSerial = new SoftwareSerial(_pin_rx, _pin_tx);

	softSerial->begin(9600);

	sds_data = softSerial;
}
#endif

void SDS011::begin(HardwareSerial* serial) {
	serial->begin(9600);
	sds_data = serial;
}

#ifdef ESP32
void SDS011::begin(HardwareSerial* serial, int8_t rxPin, int8_t txPin) {
	serial->begin(9600, SERIAL_8N1, rxPin, txPin);
	sds_data = serial;
}
#endif

#ifndef ESP32
void SDS011::begin(SoftwareSerial* serial) {
	serial->begin(9600);
	sds_data = serial;
}
#endif