deep sleep mode, remember the variable

[Tyson5]

Hi,

I use this simple example program with esp 01 and dht11 sensor. The esp controller send the measured data via MQTT protocol to a raspberry pi.

Code: Select all

#include <ESP8266WiFi.h>
#include <Wire.h>
#include <PubSubClient.h>

#include "DHT.h"

#define DHTPIN 2 // what digital pin we're connected to NodeMCU (D6)

// Uncomment whatever type you're using!
#define DHTTYPE DHT11 // DHT 11


DHT dht(DHTPIN, DHTTYPE);

#define wifi_ssid "dlink"
#define wifi_password "uazuazuaz"

#define mqtt_server "192.168.1.30"
//#define mqtt_user "user"
//#define mqtt_password "password"

#define humidity_topic "hum"
#define temperature_celsius_topic "cels"
#define temperature_fahrenheit_topic "fahr"

WiFiClient espClient;
PubSubClient client(espClient);

void setup() {
  Serial.begin(115200);
  dht.begin();
  setup_wifi();
  client.setServer(mqtt_server, 1883);
}

String macToStr(const uint8_t* mac)
{
  String result;
  for (int i = 0; i < 6; ++i) {
    result += String(mac[i], 16);
    if (i < 5)
      result += ':';
  }
  return result;
}


void setup_wifi() {
  delay(10);
  // We start by connecting to a WiFi network
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(wifi_ssid);

  WiFi.begin(wifi_ssid, wifi_password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  Serial.println("");
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
}

void reconnect() {
  // Loop until we're reconnected
  while (!client.connected()) {
        Serial.print("Attempting MQTT connection...");
    
          // Generate client name based on MAC address and last 8 bits of microsecond counter
      String clientName;  
      clientName += "esp8266-";
      uint8_t mac[6];
      WiFi.macAddress(mac);
      clientName += macToStr(mac);
      clientName += "-";
      clientName += String(micros() & 0xff, 16);
      Serial.print("Connecting to ");
      Serial.print(mqtt_server);
      Serial.print(" as ");
      Serial.println(clientName);


    // Attempt to connect
    // If you do not want to use a username and password, change next line to
  if (client.connect((char*) clientName.c_str())) {
    //if (client.connect((char*) clientName.c_str()), mqtt_user, mqtt_password)) {
      Serial.println("connected");
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      // Wait 5 seconds before retrying
      delay(2000);
    }
  }
}


void loop() {
  
      if (!client.connected()) {
        reconnect();
      }
      client.loop();

      // Wait a few seconds between measurements.
      delay(100);
      
      // Reading temperature or humidity takes about 250 milliseconds!
      // Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)
      float h = dht.readHumidity();
      // Read temperature as Celsius (the default)
      float t = dht.readTemperature();
      // Read temperature as Fahrenheit (isFahrenheit = true)
      float f = dht.readTemperature(true);
      
      // Check if any reads failed and exit early (to try again).
      if (isnan(h) || isnan(t) || isnan(f)) {
      Serial.println("Failed to read from DHT sensor!");
      return;
      }
      
      // Compute heat index in Fahrenheit (the default)
      float hif = dht.computeHeatIndex(f, h);
      // Compute heat index in Celsius (isFahreheit = false)
      float hic = dht.computeHeatIndex(t, h, false);
      Serial.print("Humidity: ");
      Serial.print(h);
      Serial.print(" %\t");
      Serial.print("Temperature: ");
      Serial.print(t);
      Serial.print(" *C ");
    //  Serial.print(f);
    //  Serial.print(" *F\t");
    //  Serial.print("Heat index: ");
    //  Serial.print(hic);
    //  Serial.print(" *C ");
    //  Serial.print(hif);
    //  Serial.println(" *F");


      Serial.print("Temperature in Celsius:");
      Serial.println(String(t).c_str());
      client.publish(temperature_celsius_topic, String(t).c_str(), true);

   //   Serial.print("Temperature in Fahrenheit:");
   //   Serial.println(String(f).c_str());
   //  client.publish(temperature_fahrenheit_topic, String(f).c_str(), true);


      Serial.print("Humidity:");
      Serial.println(String(h).c_str());
      client.publish(humidity_topic, String(h).c_str(), true);
}

If i use deep-sleep mode the esp module use a few uA current, I want to do a battery power. I want to wake up and measure sensor data in about every 2-3 minutes, but i only want to send it on mqtt protocol if the data has changed compared to the previous data. Because the esp module consumes a lot of power while a wifi connection.

So how can I compare the two measured data with each other if the esp module is deep asleep? It should be a variable that remember even after a deep sleep.

[ESP_Sprite]

I think you're running Arduino on an ESP8266? You may want to look into the RTC memory example Arduino provides you. The RTC memory can retain variables even in deep sleep.

(Note that this is an ESP32 forum, not an ESP8266 one, so technically your question is off-topic.)