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What you will need:

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Project Overview

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This project is meant to give you a practical example of what you can do with IoT skills. We will be using the esp32 huzzah feather board as our microcontroller because it has the esp32 chip that can connect to the internet. We will use this connectivity to send an HTTP GET request to ThingSpeak periodically so we can chart the temperature where ever we decide to place our device.

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Setting up our Board

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Install the Arduino ide on your computer by following the instructions here.

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Download the proper USB driver for your system here.

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Next, we need to install the esp32 board in the Arduino ide. Run your ide and navigate to the preferences window. Enter https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_dev_index.json in the Additional Board Manager URLs field. Then open the board manager (Tools > Board > Board Manager) and search for esp32. Now Install esp32. Then open your boards again and select Board > ESP32 Arduino > Adafruit ESP32 Feather. To verify that you have everything set up correctly, you can run the following program to your board:

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// Code that runs once at the beginning\nvoid setup(){\n  pinMode(13, OUTPUT); // Sets the digital pin 13 as output\n}\n\n\n// Code that runs repeatedly after setup\nvoid loop(){\n  digitalWrite(13, HIGH); // Set the digital pin 13 on\n  delay(1000); // Wait 1000 ms\n  digitalWrite(13, LOW); // Set the digital pin 13 off\n  delay(1000);\n}
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If everything is good, you should see a red light blink on the board.

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Installing Libraries

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Now we are going to install libraries to make it easier for us to interface with the bme280 and connect to the internet.

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Go to Tools > Library Manager, type in Adafruit BME280 Library, and install it. It will prompt you to install other dependency libraries. Select Install All.

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Wiring

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Connect the following pins with jumper wires (esp32 to bme280):\n3V to VIN\nGND to GND\nSCL to SCK\nSDA to SDI\nYou can test if everything is wired correctly by running Adafruits example. It can be found at File > Examples > Adafruit BME280 Library > bme280test. Because we are using I2C with the default pins, we don’t have to modify anything in the example code. Run it and then open the Serial Monitor (Tools > Serial Monitor). You should see readings every second for each of the sensors that look something like this:

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Temperature = 24.93 *C\nPressure = 1004.25 hPa\nApprox. Altitude = 75.19 m\nHumidity = 47.32 %
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Setting up ThingsSpeak

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First, create a ThingsSpeak account here. Then go to the channels tab and click Create New. Name the channel something like BME280 or Sensor Test, whatever you want. Check the boxes for four fields, and enter the names Temperature, Pressure, Altitude, Humidity. Ignore the rest of the text inputs and click Save Channel.

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Now that we have our channel set up, go to the API Keys tab. Take note of the URL under Write a Channel Feed. It should look something like https://api.thingspeak.com/update?api_key=<YOUR KEY>&field1=0. Your key is the most important part and is what will allow you to get to your thing speak channel.

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Sending Data to Thing Speak

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Now let’s try sending some data to each of our channels four fields. Try out this code. Make sure to replace “ssid” with your wifi name, “password” with your wifi password, and the “serverName” with your own from ThingSpeak.

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// Import nessesary libraries\n#include <WiFi.h>\n#include <HTTPClient.h>\n\n// Set our wifi name and password\nconst char* ssid = \"YOUR_WIFI_NAME\";\nconst char* password = \"YOUR_WIFI_PASSWORD\";\n\n// Your thingspeak channel url with api_key query\nString serverName = \"https://api.thingspeak.com/update?api_key=YOUR_WRITE_KEY\";\n\n// Assign some variables to allow us read and send data every minute\nunsigned long lastTime = 0;\nunsigned long timerDelay = 60000;\n\n\nvoid setup() {\n  Serial.begin(9600); // Opens up the serial port with a baudrate of 9600 bits per second\n\n\n  WiFi.begin(ssid, password); // Attempt to connect to wifi with our password\n  Serial.println(\"Connecting\"); // Print our status to the serial monitor\n  // Wait for wifi to connect\n  while(WiFi.status() != WL_CONNECTED) {\n    delay(500);\n    Serial.print(\".\");\n  }\n  Serial.println(\"\");\n  Serial.print(\"Connected to WiFi network with IP Address: \");\n  Serial.println(WiFi.localIP());\n}\n\n\nvoid loop() {\n  if ((millis() - lastTime) > timerDelay) { // Check if its been a minute\n    if(WiFi.status()== WL_CONNECTED){ // Check to make sure wifi is still connected\n      sendData(1, 2, 3, 4); // Call the sendData function defined below\n    }\n    else {\n      Serial.println(\"WiFi Disconnected\");\n    }\n    lastTime = millis();\n  }\n}\n\n\nvoid sendData(double temp, double pres, double alt, double hum){\n  HTTPClient http; // Initialize our HTTP client\n\n\n  String url = serverName + \"&field1=\" + temp + \"&field2=\" + pres + \"&field3=\" + alt + \"&field4=\" + hum; // Define our entire url\n      \n  http.begin(url.c_str()); // Initialize our HTTP request\n      \n  int httpResponseCode = http.GET(); // Send HTTP request\n      \n  if (httpResponseCode > 0){ // Check for good HTTP status code\n    Serial.print(\"HTTP Response code: \");\n    Serial.println(httpResponseCode);\n  }else{\n    Serial.print(\"Error code: \");\n    Serial.println(httpResponseCode);\n  }\n  http.end();\n}
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Again check the serial monitor to see if you connected to wifi and when the data is sent. It will take 60 seconds to send first and then send again every 60. You should see the points show up on your charts.

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Right now we are just adding the values 1, 2, 3, and 4 to the charts repeatedly. Let’s try to get our live sensor data in there now.

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Sending Live Data to ThingSpeak

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Now we are going to combine everything to finaly get our data from the sensor then send it to our ThingSpeak channel. You will probobly want to clear your channel before you start getting real data. To clear it go to Channel Settings and click Clear Channel at the bottom of the page.

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// Import nessisary libraries\n#include <WiFi.h>\n#include <HTTPClient.h>\n#include <Wire.h>\n#include <SPI.h>\n#include <Adafruit_Sensor.h>\n#include <Adafruit_BME280.h>\n\n// Set our sealevel pressure\n#define SEALEVELPRESSURE_HPA (1013.25)\n\n\nconst char* ssid = \"YOUR_WIFI_NAME\";\nconst char* password = \"YOUR_WIFI_PASSWORD\";\n\n\nString serverName = \"https://api.thingspeak.com/update?api_key=FL36D2MOEQ9HTM86\";\n\n\nunsigned long lastTime = 0;\nunsigned long timerDelay = 60000;\n\nInitialize the bme280 object\nAdafruit_BME280 bme;\n\n\nvoid setup() {\n  Serial.begin(115200); \n\n\n  initBme280(); // Initialize the bme280\n\n\n  WiFi.begin(ssid, password);\n  Serial.println(\"Connecting\");\n  while(WiFi.status() != WL_CONNECTED) {\n    delay(500);\n    Serial.print(\".\");\n  }\n  Serial.println(\"\");\n  Serial.print(\"Connected to WiFi network with IP Address: \");\n  Serial.println(WiFi.localIP());\n}\n\n\nvoid loop() {\n  if ((millis() - lastTime) > timerDelay) {\n    if(WiFi.status()== WL_CONNECTED){\n// Read data from our bme280 object and pass it to our sendData function \nsendData(bme.readTemperature(), bme.readPressure() / 100.0F, bme.readAltitude(SEALEVELPRESSURE_HPA), bme.readHumidity());\n    }\n    else {\n      Serial.println(\"WiFi Disconnected\");\n    }\n    lastTime = millis();\n  }\n}\n\n\nvoid sendData(double temp, double pres, double alt, double hum){\n    HTTPClient http;\n\n\n    String url = serverName + \"&field1=\" + temp + \"&field2=\" + pres + \"&field3=\" + alt + \"&field4=\" + hum;\n      \n    http.begin(url.c_str());\n      \n    int httpResponseCode = http.GET();\n      \n    if (httpResponseCode > 0){\n      Serial.print(\"HTTP Response code: \");\n      Serial.println(httpResponseCode);\n    }else{\n      Serial.print(\"Error code: \");\n      Serial.println(httpResponseCode);\n    }\n    http.end();\n}\n\n\nvoid initBme280(){\n  unsigned status;\n    \n  status = bme.begin();  \n  if (!status) {\n      Serial.println(\"Could not find a valid BME280 sensor, check wiring, address, sensor ID!\");\n      Serial.print(\"SensorID was: 0x\"); Serial.println(bme.sensorID(),16);\n      Serial.print(\"        ID of 0xFF probably means a bad address, a BMP 180 or BMP 085\\n\");\n      Serial.print(\"   ID of 0x56-0x58 represents a BMP 280,\\n\");\n      Serial.print(\"        ID of 0x60 represents a BME 280.\\n\");\n      Serial.print(\"        ID of 0x61 represents a BME 680.\\n\");\n      while (1) delay(10);\n  }\n  Serial.println(\"BME280 Initialized\");\n  Serial.println();\n}
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Congrats! You should now have live data once a minute. If you ever want to change that time, simply change the timerDelay to the number of millis you want it to wait.

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