sds011-esp8266.ino

#include <ESP8266WiFi.h>
#define DEBUG

// Wi-Fi Settings
const char* ssid = "freifunk-myk.de"; // your wireless network name (SSID)
const char* password = ""; // your Wi-Fi network password

WiFiClient client;

// ThingSpeak Settings
const int channelID = 230627;
String writeAPIKey = "1DD12C70KTO4UNP0"; // write API key for your ThingSpeak Channel
const char* server = "api.thingspeak.com";

char sds_buffer[11];
byte sds_buffer_pos_w=0;

void bufferClear() {
  for(sds_buffer_pos_w=0; sds_buffer_pos_w<11; sds_buffer_pos_w++) sds_buffer[sds_buffer_pos_w] = 0x00;
  sds_buffer_pos_w=0;
}

void setup() {
  Serial.begin(9600);

  WiFi.begin(ssid);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
  }

  #ifdef DEBUG
    Serial.println(F("SDS011-Monitor Debug Console"));
  #endif
  bufferClear();
}

void loop() {

  unsigned int pm25=0;
  unsigned int pm10=0;
  unsigned int devId=0;
  byte checksum=0;
  
  if(Serial.available()) {
    sds_buffer[sds_buffer_pos_w] = Serial.read();

    #ifdef DEBUG
      Serial.print(F("RX: 0x"));
      Serial.print(sds_buffer[sds_buffer_pos_w], 16);
      Serial.print(F(" at position 0x"));
      Serial.println(sds_buffer_pos_w, 16);
    #endif
    
    if(sds_buffer[0] != 0xAA) {
      sds_buffer_pos_w=0;
      #ifdef DEBUG
        Serial.println(F("Invalid start byte"));
      #endif
      return;
    }
    sds_buffer_pos_w++;

    if(sds_buffer_pos_w < 10) return;

    if(sds_buffer[9] != 0xAB) {
      //Narf...
      sds_buffer_pos_w=0;
      sds_buffer[0]=0x00;
      #ifdef DEBUG
        Serial.println(F("Invalid stop byte"));
      #endif
      return;
    }

    if(sds_buffer[1] != 0xC0) {
      bufferClear();
      #ifdef DEBUG
        Serial.println(F("Invalid command byte"));
      #endif
      return;
    }

    pm10  = (sds_buffer[4] + (sds_buffer[5] << 8));
    pm25  = (sds_buffer[2] + (sds_buffer[3] << 8));
    devId = (sds_buffer[6] + (sds_buffer[7] << 8));

    for(sds_buffer_pos_w=2; sds_buffer_pos_w<8; sds_buffer_pos_w++) checksum += sds_buffer[sds_buffer_pos_w];

    if(checksum != sds_buffer[8]) {
      //Narf…
      bufferClear();
      #ifdef DEBUG
        Serial.print(F("Invalid CRC byte: 0x"));
        Serial.print(checksum, 16);
        Serial.print(F(" != 0x"));
        Serial.println((byte)sds_buffer[8], 16);
      #endif
      return;
    }

    #ifdef DEBUG
      Serial.print(F("PM10: "));
      Serial.print(pm10);
      Serial.print(F(" - PM2.5: "));
      Serial.println(pm25);
    #endif
    HTTPSendData(pm10, pm25);
    
    bufferClear();
  }
}



bool HTTPSendData(unsigned int pm10, unsigned int pm25) {
  if (client.connect(server, 80)) {
    // Construct API request body
    String body = "field1=";
           body += String(pm10);
           body += "&field2=";
           body += String(pm25);

    client.print("POST /update HTTP/1.1\n");
    client.print("Host: api.thingspeak.com\n");
    client.print("Connection: close\n");
    client.print("X-THINGSPEAKAPIKEY: " + writeAPIKey + "\n");
    client.print("Content-Type: application/x-www-form-urlencoded\n");
    client.print("Content-Length: ");
    client.print(body.length());
    client.print("\n\n");
    client.print(body);
    client.print("\n\n");

    #ifdef DEBUG
      Serial.print("Message to ");
      Serial.println(server);
      Serial.print("POST /update HTTP/1.1\n");
      Serial.print("Host: api.thingspeak.com\n");
      Serial.print("Connection: close\n");
      Serial.print("X-THINGSPEAKAPIKEY: " + writeAPIKey + "\n");
      Serial.print("Content-Type: application/x-www-form-urlencoded\n");
      Serial.print("Content-Length: ");
      Serial.print(body.length());
      Serial.print("\n\n");
      Serial.print(body);
      Serial.print("\n\n");
    #endif
  }
}