ESP32 Pico Kit GPIO control and DHT22 sensor monitor using ThingsBoard Arduino SDK

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#include <DHTesp.h>         // DHT for ESP32 library
#include <WiFi.h>           // WiFi control for ESP32
#include <ThingsBoard.h>    // ThingsBoard SDK

// Helper macro to calculate array size
#define COUNT_OF(x) ((sizeof(x)/sizeof(0[x])) / ((size_t)(!(sizeof(x) % sizeof(0[x])))))

// WiFi access point
#define WIFI_AP_NAME        "WIFI_AP"
// WiFi password
#define WIFI_PASSWORD       "WIFI_PASSWORD"

// See https://thingsboard.io/docs/getting-started-guides/helloworld/ 
// to understand how to obtain an access token
#define TOKEN               "TOKEN"
// ThingsBoard server instance.
#define THINGSBOARD_SERVER  "demo.thingsboard.io"

// Baud rate for debug serial
#define SERIAL_DEBUG_BAUD    115200

// Initialize ThingsBoard client
WiFiClient espClient;
// Initialize ThingsBoard instance
ThingsBoard tb(espClient);
// the Wifi radio's status
int status = WL_IDLE_STATUS;

// Array with LEDs that should be lit up one by one
uint8_t leds_cycling[] = { 25, 26, 32 };
// Array with LEDs that should be controlled from ThingsBoard, one by one
uint8_t leds_control[] = { 19, 22, 21 };

// DHT object
DHTesp dht;
// ESP32 pin used to query DHT22
#define DHT_PIN 33

// Main application loop delay
int quant = 20;

// Initial period of LED cycling.
int led_delay = 1000;
// Period of sending a temperature/humidity data.
int send_delay = 2000;

// Time passed after LED was turned ON, milliseconds.
int led_passed = 0;
// Time passed after temperature/humidity data was sent, milliseconds.
int send_passed = 0;

// Set to true if application is subscribed for the RPC messages.
bool subscribed = false;
// LED number that is currenlty ON.
int current_led = 0;

// Processes function for RPC call "setValue"
// RPC_Data is a JSON variant, that can be queried using operator[]
// See https://arduinojson.org/v5/api/jsonvariant/subscript/ for more details
RPC_Response processDelayChange(const RPC_Data &data)
{
  Serial.println("Received the set delay RPC method");

  // Process data

  led_delay = data;

  Serial.print("Set new delay: ");
  Serial.println(led_delay);

  return RPC_Response(NULL, led_delay);
}

// Processes function for RPC call "getValue"
// RPC_Data is a JSON variant, that can be queried using operator[]
// See https://arduinojson.org/v5/api/jsonvariant/subscript/ for more details
RPC_Response processGetDelay(const RPC_Data &data)
{
  Serial.println("Received the get value method");

  return RPC_Response(NULL, led_delay);
}

// Processes function for RPC call "setGpioStatus"
// RPC_Data is a JSON variant, that can be queried using operator[]
// See https://arduinojson.org/v5/api/jsonvariant/subscript/ for more details
RPC_Response processSetGpioState(const RPC_Data &data)
{
  Serial.println("Received the set GPIO RPC method");

  int pin = data["pin"];
  bool enabled = data["enabled"];

  if (pin < COUNT_OF(leds_control)) {
    Serial.print("Setting LED ");
    Serial.print(pin);
    Serial.print(" to state ");
    Serial.println(enabled);

    digitalWrite(leds_control[pin], enabled);
  }

  return RPC_Response(data["pin"], (bool)data["enabled"]);
}

// RPC handlers
RPC_Callback callbacks[] = {
  { "setValue",         processDelayChange },
  { "getValue",         processGetDelay },
  { "setGpioStatus",    processSetGpioState },
};

// Setup an application
void setup() {
  // Initialize serial for debugging
  Serial.begin(SERIAL_DEBUG_BAUD);
  WiFi.begin(WIFI_AP_NAME, WIFI_PASSWORD);
  InitWiFi();

  // Pinconfig

  for (size_t i = 0; i < COUNT_OF(leds_cycling); ++i) {
    pinMode(leds_cycling[i], OUTPUT);
  }

  for (size_t i = 0; i < COUNT_OF(leds_control); ++i) {
    pinMode(leds_control[i], OUTPUT);
  }

  // Initialize temperature sensor
  dht.setup(DHT_PIN, DHTesp::DHT22);
}

// Main application loop
void loop() {
  delay(quant);

  led_passed += quant;
  send_passed += quant;

  // Check if next LED should be lit up
  if (led_passed > led_delay) {
    // Turn off current LED
    digitalWrite(leds_cycling[current_led], LOW);
    led_passed = 0;
    current_led = current_led >= 2 ? 0 : (current_led + 1);
    // Turn on next LED in a row
    digitalWrite(leds_cycling[current_led], HIGH);
  }

  // Reconnect to WiFi, if needed
  if (WiFi.status() != WL_CONNECTED) {
    reconnect();
    return;
  }

  // Reconnect to ThingsBoard, if needed
  if (!tb.connected()) {
    subscribed = false;

    // Connect to the ThingsBoard
    Serial.print("Connecting to: ");
    Serial.print(THINGSBOARD_SERVER);
    Serial.print(" with token ");
    Serial.println(TOKEN);
    if (!tb.connect(THINGSBOARD_SERVER, TOKEN)) {
      Serial.println("Failed to connect");
      return;
    }
  }

  // Subscribe for RPC, if needed
  if (!subscribed) {
    Serial.println("Subscribing for RPC...");

    // Perform a subscription. All consequent data processing will happen in
    // callbacks as denoted by callbacks[] array.
    if (!tb.RPC_Subscribe(callbacks, COUNT_OF(callbacks))) {
      Serial.println("Failed to subscribe for RPC");
      return;
    }

    Serial.println("Subscribe done");
    subscribed = true;
  }

  // Check if it is a time to send DHT22 temperature and humidity
  if (send_passed > send_delay) {
    Serial.println("Sending data...");

    // Uploads new telemetry to ThingsBoard using MQTT. 
    // See https://thingsboard.io/docs/reference/mqtt-api/#telemetry-upload-api 
    // for more details

    TempAndHumidity lastValues = dht.getTempAndHumidity();    
    if (isnan(lastValues.humidity) || isnan(lastValues.temperature)) {
      Serial.println("Failed to read from DHT sensor!");
    } else {
      tb.sendTelemetryFloat("temperature", lastValues.temperature);
      tb.sendTelemetryFloat("humidity", lastValues.humidity);
    }

    send_passed = 0;
  }

  // Process messages
  tb.loop();
}

void InitWiFi()
{
  Serial.println("Connecting to AP ...");
  // attempt to connect to WiFi network

  WiFi.begin(WIFI_AP_NAME, WIFI_PASSWORD);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("Connected to AP");
}

void reconnect() {
  // Loop until we're reconnected
  status = WiFi.status();
  if ( status != WL_CONNECTED) {
    WiFi.begin(WIFI_AP_NAME, WIFI_PASSWORD);
    while (WiFi.status() != WL_CONNECTED) {
      delay(500);
      Serial.print(".");
    }
    Serial.println("Connected to AP");
  }
}