Ishan Ajay
Published © GPL3+

Log temperature data to Google Sheets

Temperature logger using ESP8266

AdvancedFull instructions provided286
Log temperature data to Google Sheets

Things used in this project

Hardware components

Breadboard (generic)
Breadboard (generic)
Organize Components.
×1
DHT22 Temperature and Humidity Sensor
DFRobot DHT22 Temperature and Humidity Sensor
Temperature Sensor
×1
Micro-USB to USB Cable (Generic)
Micro-USB to USB Cable (Generic)
Connect ESP8266 To Computer
×1
NodeMCU ESP8266 Breakout Board
NodeMCU ESP8266 Breakout Board
WiFi Module And Programmer Board
×1

Software apps and online services

Arduino IDE
Arduino IDE
Program ESP8266
Google Sheets
Google Sheets
Read Data from DHT22

Story

Read more

Schematics

diagram

These are the connections.

Code

Code

C/C++
This is the code:
#include <ESP8266WiFi.h>
#include "HTTPSRedirect.h"
#include "DebugMacros.h"
#include <DHT.h>

#define DHTPIN D4                                                           // what digital pin we're connected to
#define DHTTYPE DHT11                                                       // select dht type as DHT 11 or DHT22
DHT dht(DHTPIN, DHTTYPE);

float h;
float t;
String sheetHumid = "";
String sheetTemp = "";

const char* ssid = "";                //replace with our wifi ssid
const char* password = "";         //replace with your wifi password

const char* host = "script.google.com";
const char *GScriptId = "AKfycbxy9wAZKoPIpPq5AvqYTFFn5kkqK_-avacf2NU_w7ycoEtlkuNt"; // Replace with your own google script id
const int httpsPort = 443; //the https port is same

// echo | openssl s_client -connect script.google.com:443 |& openssl x509 -fingerprint -noout
const char* fingerprint = "";

//const uint8_t fingerprint[20] = {};

String url = String("/macros/s/") + GScriptId + "/exec?value=Temperature";  // Write Teperature to Google Spreadsheet at cell A1
// Fetch Google Calendar events for 1 week ahead
String url2 = String("/macros/s/") + GScriptId + "/exec?cal";  // Write to Cell A continuosly

//replace with sheet name not with spreadsheet file name taken from google
String payload_base =  "{\"command\": \"appendRow\", \
                    \"sheet_name\": \"TempSheet\", \
                       \"values\": ";
String payload = "";

HTTPSRedirect* client = nullptr;

// used to store the values of free stack and heap before the HTTPSRedirect object is instantiated
// so that they can be written to Google sheets upon instantiation

void setup() {
  delay(1000);
  Serial.begin(115200);
  dht.begin();     //initialise DHT11

  Serial.println();
  Serial.print("Connecting to wifi: ");
  Serial.println(ssid);
  
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());

  // Use HTTPSRedirect class to create a new TLS connection
  client = new HTTPSRedirect(httpsPort);
  client->setInsecure();
  client->setPrintResponseBody(true);
  client->setContentTypeHeader("application/json");
  Serial.print("Connecting to ");
  Serial.println(host);          //try to connect with "script.google.com"

  // Try to connect for a maximum of 5 times then exit
  bool flag = false;
  for (int i = 0; i < 5; i++) {
    int retval = client->connect(host, httpsPort);
    if (retval == 1) {
      flag = true;
      break;
    }
    else
      Serial.println("Connection failed. Retrying...");
  }

  if (!flag) {
    Serial.print("Could not connect to server: ");
    Serial.println(host);
    Serial.println("Exiting...");
    return;
  }
// Finish setup() function in 1s since it will fire watchdog timer and will reset the chip.
//So avoid too many requests in setup()

  Serial.println("\nWrite into cell 'A1'");
  Serial.println("------>");
  // fetch spreadsheet data
  client->GET(url, host);
  
  Serial.println("\nGET: Fetch Google Calendar Data:");
  Serial.println("------>");
  // fetch spreadsheet data
  client->GET(url2, host);

 Serial.println("\nStart Sending Sensor Data to Google Spreadsheet");

  
  // delete HTTPSRedirect object
  delete client;
  client = nullptr;
}

void loop() {

  h = dht.readHumidity();                                              // Reading temperature or humidity takes about 250 milliseconds!
  t = dht.readTemperature();                                           // Read temperature as Celsius (the default)
  if (isnan(h) || isnan(t)) {                                                // Check if any reads failed and exit early (to try again).
    Serial.println(F("Failed to read from DHT sensor!"));
    return;
  }
  Serial.print("Humidity: ");  Serial.print(h);
  sheetHumid = String(h) + String("%");                                         //convert integer humidity to string humidity
  Serial.print("%  Temperature: ");  Serial.print(t);  Serial.println("°C ");
  sheetTemp = String(t) + String("°C");

  static int error_count = 0;
  static int connect_count = 0;
  const unsigned int MAX_CONNECT = 20;
  static bool flag = false;

  payload = payload_base + "\"" + sheetTemp + "," + sheetHumid + "\"}";

  if (!flag) {
    client = new HTTPSRedirect(httpsPort);
    client->setInsecure();
    flag = true;
    client->setPrintResponseBody(true);
    client->setContentTypeHeader("application/json");
  }

  if (client != nullptr) {
    if (!client->connected()) {
      client->connect(host, httpsPort);
      client->POST(url2, host, payload, false);
      Serial.print("Sent : ");  Serial.println("Temp and Humid");
    }
  }
  else {
    DPRINTLN("Error creating client object!");
    error_count = 5;
  }

  if (connect_count > MAX_CONNECT) {
    connect_count = 0;
    flag = false;
    delete client;
    return;
  }

//  Serial.println("GET Data from cell 'A1':");
//  if (client->GET(url3, host)) {
//    ++connect_count;
//  }
//  else {
//    ++error_count;
//    DPRINT("Error-count while connecting: ");
//    DPRINTLN(error_count);
//  }

  Serial.println("POST or SEND Sensor data to Google Spreadsheet:");
  if (client->POST(url2, host, payload)) {
    ;
  }
  else {
    ++error_count;
    DPRINT("Error-count while connecting: ");
    DPRINTLN(error_count);
  }

  if (error_count > 3) {
    Serial.println("Halting processor...");
    delete client;
    client = nullptr;
    Serial.printf("Final free heap: %u\n", ESP.getFreeHeap());
    Serial.printf("Final stack: %u\n", ESP.getFreeContStack());
    Serial.flush();
    ESP.deepSleep(0);
  }
  
  delay(3000);    // keep delay of minimum 2 seconds as dht allow reading after 2 seconds interval and also for google sheet
}

Credits

Ishan Ajay

Ishan Ajay

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