ThingSpeak
ThingSpeak Communication Library for Arduino, ESP8266 & EPS32
ThingSpeak ( https://www.thingspeak.com ) is an analytic IoT platform service that allows you to aggregate, visualize and analyze live data streams in the cloud.
Compatibility
This library is compatible with the avr, esp8266, sam, samd, esp32, samd_beta, megaavr architectures so you should be able to use it on the following Arduino boards:
- Arduino Micro
- Arduino Leonardo
- Arduino Mega
- Arduino Due
- Arduino MKR FOX 1200
- Arduino MKR GSM 1400
- Arduino MKR NB 1500
- Arduino MKR VIDOR 4000
- Arduino MKR WAN 1300 (LoRa connectivity)
- Arduino MKR WAN 1310
- Arduino MKR WiFi 1010
- Arduino MKR ZERO (I2S bus & SD for sound, music & digital audio data)
- Arduino MKR1000 WIFI
- Arduino Nano
- Arduino Nano 33 IoT
- Arduino Nano Every
- Arduino Uno
- Arduino Uno WiFi REV2
- Arduino Yún
- Arduino Zero
Compatibility Note
Note: while the library is supposed to compile correctly on these architectures, it might require specific hardware features that may be available only on some boards.
Releases
To use this library, open the Library Manager in the Arduino IDE and install it from there.
Publish and Subscribe to a ThingSpeak Channel Using Secure MQTT
This example shows how to use an ESP8266 board to record RSSI data in ThingSpeak™ via secure MQTT. You can modify the code as indicated in its comments to adapt it for other boards or nonsecure MQTT.
Setup
1) Create a ThingSpeak channel, as shown in Collect Data in a New Channel.
2) Create an MQTT device by clicking Devices > MQTT at the top of the ThingSpeak page, then Add Device. When setting up the device and adding the new channel to its authorized list, click Download Credentials > Plain Text. For details, see Create a ThingSpeak MQTT Device. Use the saved credentials in the Code section below.
3) Add the ESP8266 Board Package:
a. Under File > Preferences, enter https://arduino.esp8266.com/stable/package_esp8266com_index.json into Additional Board Manager URLs.
b. Select Tools > Boards > Board Manager. Enter ESP8266 in the search bar and install the package.
4) Download the libraries WiFi.h and WiFiClientSecure.h to your Arduino IDE.
Code
1) Define the wireless network, ThingSpeak MQTT credentials to connect your board, connection security, and include appropriate libraries. Edit this code for your particular credentials and setup.
// Ensure correct credentials to connect to your WiFi Network. char ssid[] = "ENTER_YOUR_WIFI_SSID"; char pass[] = "ENTER_YOUR_WIFI_PASSWORD"; // Ensure that the credentials here allow you to publish and subscribe to the ThingSpeak channel. #define channelID ENTER_YOUR_THINGSPEAK_CHANNEL_NUMBER const char mqttUserName[] = "ENTER_YOUR_MQTT_USERNAME"; const char clientID[] = "ENTER_YOUR_MQTT_CLIENT_ID"; const char mqttPass[] = "ENTER_YOUR_MQTT_PASSWORD"; // It is strongly recommended to use secure connections. However, certain hardware does not work with the WiFiClientSecure library. // Comment out the following #define to use non-secure MQTT connections to ThingSpeak server. #define USESECUREMQTT // Comment the following line if not using an ESP8266. #define ESP8266BOARD #include #ifdef ESP8266BOARD #include const char* PROGMEM thingspeak_cert_thumbprint = "9780c25078532fc0fd03dae01bfd8c923fff9878"; #else #include const char * PROGMEM thingspeak_ca_cert = \ "-----BEGIN CERTIFICATE-----\n" \ "MIIDxTCCAq2gAwIBAgIQAqxcJmoLQJuPC3nyrkYldzANBgkqhkiG9w0BAQUFADBs\n" \ "MQswCQYDVQQGEwJVUzEVMBMGA1UEChMMRGlnaUNlcnQgSW5jMRkwFwYDVQQLExB3\n" \ "d3cuZGlnaWNlcnQuY29tMSswKQYDVQQDEyJEaWdpQ2VydCBIaWdoIEFzc3VyYW5j\n" \ "ZSBFViBSb290IENBMB4XDTA2MTExMDAwMDAwMFoXDTMxMTExMDAwMDAwMFowbDEL\n" \ "MAkGA1UEBhMCVVMxFTATBgNVBAoTDERpZ2lDZXJ0IEluYzEZMBcGA1UECxMQd3d3\n" \ "LmRpZ2ljZXJ0LmNvbTErMCkGA1UEAxMiRGlnaUNlcnQgSGlnaCBBc3N1cmFuY2Ug\n" \ "RVYgUm9vdCBDQTCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBAMbM5XPm\n" \ "+9S75S0tMqbf5YE/yc0lSbZxKsPVlDRnogocsF9ppkCxxLeyj9CYpKlBWTrT3JTW\n" \ "PNt0OKRKzE0lgvdKpVMSOO7zSW1xkX5jtqumX8OkhPhPYlG++MXs2ziS4wblCJEM\n" \ "xChBVfvLWokVfnHoNb9Ncgk9vjo4UFt3MRuNs8ckRZqnrG0AFFoEt7oT61EKmEFB\n" \ "Ik5lYYeBQVCmeVyJ3hlKV9Uu5l0cUyx+mM0aBhakaHPQNAQTXKFx01p8VdteZOE3\n" \ "hzBWBOURtCmAEvF5OYiiAhF8J2a3iLd48soKqDirCmTCv2ZdlYTBoSUeh10aUAsg\n" \ "EsxBu24LUTi4S8sCAwEAAaNjMGEwDgYDVR0PAQH/BAQDAgGGMA8GA1UdEwEB/wQF\n" \ "MAMBAf8wHQYDVR0OBBYEFLE+w2kD+L9HAdSYJhoIAu9jZCvDMB8GA1UdIwQYMBaA\n" \ "FLE+w2kD+L9HAdSYJhoIAu9jZCvDMA0GCSqGSIb3DQEBBQUAA4IBAQAcGgaX3Nec\n" \ "nzyIZgYIVyHbIUf4KmeqvxgydkAQV8GK83rZEWWONfqe/EW1ntlMMUu4kehDLI6z\n" \ "eM7b41N5cdblIZQB2lWHmiRk9opmzN6cN82oNLFpmyPInngiK3BD41VHMWEZ71jF\n" \ "hS9OMPagMRYjyOfiZRYzy78aG6A9+MpeizGLYAiJLQwGXFK3xPkKmNEVX58Svnw2\n" \ "Yzi9RKR/5CYrCsSXaQ3pjOLAEFe4yHYSkVXySGnYvCoCWw9E1CAx2/S6cCZdkGCe\n" \ "vEsXCS+0yx5DaMkHJ8HSXPfqIbloEpw8nL+e/IBcm2PN7EeqJSdnoDfzAIJ9VNep\n" \ "+OkuE6N36B9K\n" \ "-----END CERTIFICATE-----\n"; #endif #ifdef USESECUREMQTT #include #define mqttPort 8883 WiFiClientSecure client; #else #define mqttPort 1883 WiFiClient client; #endif
2) Define connection parameters and initialize a PubSubClient instance.
const char* server = "mqtt3.thingspeak.com"; int status = WL_IDLE_STATUS; long lastPublishMillis = 0; int connectionDelay = 1; int updateInterval = 15; PubSubClient mqttClient( client );
3) Process incoming subscription messages, subscribe to receive updates, and publish messages.
// Function to handle messages from MQTT subscription. void mqttSubscriptionCallback( char* topic, byte* payload, unsigned int length ) < // Print the details of the message that was received to the serial monitor. Serial.print("Message arrived ["); Serial.print(topic); Serial.print("] "); for (int i = 0; i < length; i++) < Serial.print((char)payload[i]); >Serial.println(); > // Subscribe to ThingSpeak channel for updates. void mqttSubscribe( long subChannelID ) < String myTopic = "channels/"+String( subChannelID )+"/subscribe"; mqttClient.subscribe(myTopic.c_str()); >// Publish messages to a ThingSpeak channel. void mqttPublish(long pubChannelID, String message) < String topicString ="channels/" + String( pubChannelID ) + "/publish"; mqttClient.publish( topicString.c_str(), message.c_str() ); >
4) Connect to WiFi and the MQTT server.
// Connect to WiFi. void connectWifi() < Serial.print( "Connecting to Wi-Fi. " ); // Loop until WiFi connection is successful #ifdef ESP8266BOARD while ( WiFi.waitForConnectResult() != WL_CONNECTED ) < #else while ( WiFi.status() != WL_CONNECTED ) < #endif WiFi.begin( ssid, pass ); delay( connectionDelay*1000 ); Serial.print( WiFi.status() ); >Serial.println( "Connected to Wi-Fi." ); > // Connect to MQTT server. void mqttConnect() < // Loop until connected. while ( !mqttClient.connected() ) < // Connect to the MQTT broker. if ( mqttClient.connect( clientID, mqttUserName, mqttPass ) ) < Serial.print( "MQTT to " ); Serial.print( server ); Serial.print (" at port "); Serial.print( mqttPort ); Serial.println( " successful." ); >else < Serial.print( "MQTT connection failed, rc = " ); // See https://pubsubclient.knolleary.net/api.html#state for the failure code explanation. Serial.print( mqttClient.state() ); Serial.println( " Will try again in a few seconds" ); delay( connectionDelay*1000 ); >> >
5) Initialize serial data transfer, and set the MQTT broker details in the setup method.
void setup() < Serial.begin( 115200 ); // Delay to allow serial monitor to come up. delay(3000); // Connect to Wi-Fi network. connectWifi(); // Configure the MQTT client mqttClient.setServer( server, mqttPort ); // Set the MQTT message handler function. mqttClient.setCallback( mqttSubscriptionCallback ); // Set the buffer to handle the returned JSON. NOTE: A buffer overflow of the message buffer will result in your callback not being invoked. mqttClient.setBufferSize( 2048 ); // Use secure MQTT connections if defined. #ifdef USESECUREMQTT // Handle functionality differences of WiFiClientSecure library for different boards. #ifdef ESP8266BOARD client.setFingerprint(thingspeak_cert_thumbprint); #else client.setCACert(thingspeak_ca_cert); #endif #endif >
6) Maintain the MQTT connection, and publish data to the channel at regular time intervals in the loop method.
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Send Data to ThingSpeak with Arduino
In order to send data to ThingSpeak™ using an Arduino ® , you need an Arduino with network connectivity either onboard or with a shield. ThingSpeak has an official library that requires Arduino 1.6.x or above running on Windows ® , MAC OS X ® , or Linux ® . This library needs to be installed and used by the Arduino device in order to send data to ThingSpeak using one of the examples.
Setup ThingSpeak
ThingSpeak requires a user account and a channel. A channel is where you send data and where ThingSpeak stores data. Each channel has up to 8 data fields, location fields, and a status field. You can send data every 15 seconds to ThingSpeak, but most applications work well every minute.
- Sign up for a new User Account – https://thingspeak.com
- Create a new Channel by selecting Channels, My Channels, and then New Channel
- Note the Write API Key and Channel ID
Full REST Interface API information for ThingSpeak is available in the documentation.
Install ThingSpeak Communication Library for Arduino
In the Arduino IDE, choose Sketch/Include Library/Manage Libraries. Click the ThingSpeak Library from the list, and click the Install button.
Setup Arduino Sketch
We have provided a few Arduino sketch examples with the ThingSpeak library. They are designed to work right away with no changes. To make the examples work with your ThingSpeak channel, you will need to configure the myChannelNumber and myWriteAPIKey variables.
unsigned long myChannelNumber = 31461; const char * myWriteAPIKey = "LD79EOAAWRVYF04Y";
Send an Analog Voltage to ThingSpeak
The WriteSingleField Arduino sketch example reads an analog voltage from pin 0, and writes it to a channel on ThingSpeak every 20 seconds. Load the example in the Arduino IDE. Make sure to select the correct Arduino board and COM port. Then, upload the code to your Arduino.
Sending Multiple Values to ThingSpeak
Since ThingSpeak supports up to 8 data fields, you might want to send more than one value to ThingSpeak. To send multiple values to ThingSpeak from an Arduino, you use ThingSpeak.setField(#,value) for each value to send and then use ThingSpeak. writeFields (myChannelNumber, myWriteAPIKey) to send everything to ThingSpeak. Use the WriteMultipleFields Arduino sketch example to send multiple pin voltages to ThingSpeak.
Examples
The library includes several examples organized by board type to help you get started. These are accessible in the Examples > ThingSpeak menu of the Arduino IDE.
- ReadField: Reading from a public channel and a private channel on ThingSpeak.
- WriteSingleField: Writing a value to a single field on ThingSpeak.
- WriteMultipleFields: Writing values to multiple fields and status in one transaction with ThingSpeak.
Complete source code and examples for the ThingSpeak Library are available on GitHub.
MATLAB Visualization
Now that your data is on ThingSpeak you can see this data on ThingSpeak using the MATLAB Visualizations app. On ThingSpeak, select Apps and then MATLAB Visualizations. Click “New”, select “Custom (no starter code), and click “Create”.
Enter the following MATLAB code and click Run and Save:
readChannelID = 93156; fieldID1 = 1; readAPIKey = 'MCI6XM81ZFOY8UCE'; %% Read Data %% [data, time] = thingSpeakRead(readChannelID, 'Field', fieldID1, 'NumPoints', 10, 'ReadKey', readAPIKey); %% Visualize Data %% plot(time, data);
Support
If you need support for the ThingSpeak Arduino Library, use the ThingSpeak Community on MATLAB Central or join us on the Quandary Discord Server.
Additional Resources
- Source Code for the ThingSpeak Arduino Library on GitHub
- Arduino Examples for ThingSpeak
Update: March 2022
ThingSpeak now supports MQTT as a way to send data to ThingSpeak. MQTT is a publish/subscribe communication protocol that uses TCP/IP sockets or WebSockets. MQTT over WebSockets can be secured with SSL. A client device connects to the MQTT broker and can publish to a channel or subscribe to updates from that channel.