SDS011

SDS011 particle matter sensor library for the Arduino framework for ESP8266 and ESP32.

This is yet another SDS011 library, this time completely non blocking. It does come with a loop()-method to poll the serial port.

Installation

• For Arduino IDE: see the Arduino Guide
• For Platformio: see the Platfomio guide

Usage

ESP8266 only has one full UART port so you may want to use SoftwareSerial on this platform.

To do something useful you can combine this lib with MQTT (like espMqttClient) as in the example below.

#include <ESP8266WiFi.h>
#include <Ticker.h>
#include <espMqttClient.h>
#include <SDS011.h>

const char SSID[] = "My_WiFi";
const char PASS[] = "My_Pass";
const IPAddress BROKER = {192, 168, 1, 10};

SDS011 sds011;
espMqttClient mqttClient;
Ticker mqttReconnectTimer;

WiFiEventHandler wifiConnectHandler;
WiFiEventHandler wifiDisconnectHandler;
Ticker wifiReconnectTimer;

bool connected = false;

void connectToWifi() {
  WiFi.begin(SSID, PASS);
}

void onWifiConnect(const WiFiEventStationModeGotIP& event) {
  connectToMqtt();
}

void onWifiDisconnect(const WiFiEventStationModeDisconnected& event) {
  mqttReconnectTimer.detach(); // ensure we don't reconnect to MQTT while reconnecting to Wi-Fi
  wifiReconnectTimer.once(2, connectToWifi);
}

void connectToMqtt() {
  if (!mqttClient.connect()) {
    mqttReconnectTimer.once(2, connectToMqtt);
}

void onMqttConnected(bool sessionPresent) {
  connected = true;
}

void onMqttDisconnect(espMqttClientTypes::DisconnectReason reason) {
  connected = false;
  if (WiFi.isConnected()) {
    mqttReconnectTimer.once(2, connectToMqtt);
  }
}

void onSensorData(float pm25Value, float pm10Value) {
  if (connected) {
    mqttClient.publish("/SENSOR/PM2_5", 1, false, String(pm25Value, 1).c_str());
    mqttClient.publish("/SENSOR/PM10", 1, false, String(pm10Value, 1).c_str());
  }
}

void onSensorResponse(uint8_t command, uint8_t set, uint8_t result) {
  // log to MQTT
}

void onSensorError(int8_t error){
  // error happened
  // -1: CRC error
}

void setup() {
  wifiConnectHandler = WiFi.onStationModeGotIP(onWifiConnect);
  wifiDisconnectHandler = WiFi.onStationModeDisconnected(onWifiDisconnect);

  mqttClient.onConnect(onMqttConnected);
  mqttClient.onDisconnect(onMqttDisconnect);
  mqttClient.setServer(BROKER, 1883);

  sds011.setup(&Serial);
  sds011.onData(onSensorData);
  sds011.onResponse(onSensorResponse);
  sds011.onError(onSensorResponse);
  sds011.setWorkingPeriod(5);

  connectToWifi();
}

void loop() {
  sds011.loop();
}

To Do

• adjust readings based on humidity
• possible timeout after sending a command
• implement missing commands
• multiple sensors (apparently the firmware supports this. However, they implemented hardware using 1-1 UART) ???

Issues, improvements?

Please create a ticket or pull request.