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This library enables an Arduino or other compatible hardware to write or read data to or from ThingSpeak, an open data platform for the Internet of Things with MATLAB analytics and visualization.

Hardware specificexamples are found here. But to give you an idea of usage examples forwriting andreading with an ESP8266 are shown below. Completedocumentation in also shown below.

ThingSpeak offers free data storage and analysis of time-stamped numeric or alphanumeric data. Users can access ThingSpeak by visitinghttp://thingspeak.com and creating a ThingSpeak user account.

ThingSpeak stores data in channels. Channels support an unlimited number of timestamped observations (think of these as rows in a spreadsheet). Each channel has up to 8 fields (think of these as columns in a speadsheet). Check out thisvideo for an overview.

Channels may be public, where anyone can see the data, or private, where only the owner and select users can read the data. Each channel has an associated Write API Key that is used to control who can write to a channel. In addition, private channels have one or more Read API Keys to control who can read from private channel. An API Key is not required to read from public channels. Each channel can have up to 8 fields. One field is created by default.

You can visualize and do online analytics of your data on ThingSpeak using the built in version of MATLAB, or use the desktop version of MATLAB to get deeper historical insight. Visithttps://www.mathworks.com/hardware-support/thingspeak.html to learn more.

Libraries and examples for Particle devices can be found here:https://github.com/mathworks/thingspeak-particle

In the Arduino IDE, choose Sketch/Include Library/Manage Libraries. Click the ThingSpeak Library from the list, and click the Install button.

--- or ---

1. Download the ZIP file (below) to your machine.
2. In the Arduino IDE, choose Sketch/Include Library/Add Zip Library
3. Navigate to the ZIP file, and click Open

• Arduino/Genuino or compatible using a WiFi Shield
• Arduino/Genuino or compatible using a WiFi Shield 101 (Use the WiFi101 library version 0.13.0 or older.)
• Arduino/Genuino or compatible using an Ethernet Shield
• Arduino/Genuino or compatible using a MKR ETH Shield
• Arduino MKR1000
• Arduino MKR1010
• Arduino VIDOR 4000
• Arduino GSM 14000
• Arduino Uno WiFi Rev2
• Arduino Yún (Rev1 and Rev2)
• ESP8266 programming directly (tested with SparkFun ESP8266 Thing - Dev Board and NodeMCU 1.0 module)
• ESP8266 via AT commands
• ESP32 (tested with SparkFun ESP32 Thing)

The library includes severalexamples organized by board type to help you get started. These are accessible in 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.

In this case, write to a field with an ESP8266 with an incrementing number.

#include "ThingSpeak.h"#include <ESP8266WiFi.h>//----------------  Fill in your credentails   ---------------------char ssid[] = "MySSID";             // your network SSID (name) char pass[] = "MyPassword";         // your network passwordunsigned long myChannelNumber = 0;  // Replace the 0 with your channel numberconst char * myWriteAPIKey = "";    // Paste your ThingSpeak Write API Key between the quotes //------------------------------------------------------------------WiFiClient  client;int number = 0;void setup() {  //Initialize serial and wait for port to open:  Serial.begin(9600);  while (!Serial) {    ; // wait for serial port to connect. Needed for native USB port only  }  WiFi.mode(WIFI_STA);  ThingSpeak.begin(client); }void loop() {  // Connect or reconnect to WiFi  if(WiFi.status() != WL_CONNECTED){    Serial.print("Attempting to connect to SSID: ");    Serial.println(SECRET_SSID);    while(WiFi.status() != WL_CONNECTED){      WiFi.begin(ssid, pass);      Serial.print(".");      delay(5000);         }     Serial.println("\nConnected.");  }    // Write to ThingSpeak. There are up to 8 fields in a channel, allowing you to store up to 8 different  // pieces of information in a channel.  Here, we write to field 1.  int x = ThingSpeak.writeField(myChannelNumber, 1, number, myWriteAPIKey);    // Check the return code  if(x == 200){    Serial.println("Channel update successful.");  }  else{    Serial.println("Problem updating channel. HTTP error code " + String(x));  }  number++;  if(number > 99){    number = 0;  }    delay(20000); // Wait 20 seconds before sending a new value}

In this case, read from a public channel and a private channel with an ESP8266. The public channel is the temperature(F) at MathWorks headquarters. The private channel is a counter that increments.

#include "ThingSpeak.h"#include <ESP8266WiFi.h>//----------------  Fill in your credentails   ---------------------char ssid[] = "MySSID";     // your network SSID (name) char pass[] = "MyPassword"; // your network password//------------------------------------------------------------------WiFiClient  client;unsigned long weatherStationChannelNumber = 12397;unsigned int temperatureFieldNumber = 4;unsigned long counterChannelNumber = 298725;const char * myCounterReadAPIKey = "SODG0O2UZVGKWAWG";unsigned int counterFieldNumber = 1; void setup() { //Initialize serial and wait for port to open: Serial.begin(9600); while (!Serial) {   ; // wait for serial port to connect. Needed for native USB port only } WiFi.mode(WIFI_STA);   ThingSpeak.begin(client);}void loop() { int statusCode = 0;  // Connect or reconnect to WiFi if(WiFi.status() != WL_CONNECTED){   Serial.print("Attempting to connect to SSID: ");   Serial.println(SECRET_SSID);   while(WiFi.status() != WL_CONNECTED){     WiFi.begin(ssid, pass);     Serial.print(".");     delay(5000);        }    Serial.println("\nConnected"); } // Read in field 4 of the public channel recording the temperature float temperatureInF = ThingSpeak.readFloatField(weatherStationChannelNumber, temperatureFieldNumber);   // Check the status of the read operation to see if it was successful statusCode = ThingSpeak.getLastReadStatus(); if(statusCode == 200){   Serial.println("Temperature at MathWorks HQ: " + String(temperatureInF) + " deg F"); } else{   Serial.println("Problem reading channel. HTTP error code " + String(statusCode));  }  delay(15000); // No need to read the temperature too often. // Read in field 1 of the private channel which is a counter   long count = ThingSpeak.readLongField(counterChannelNumber, counterFieldNumber, myCounterReadAPIKey);    // Check the status of the read operation to see if it was successful statusCode = ThingSpeak.getLastReadStatus(); if(statusCode == 200){   Serial.println("Counter: " + String(count)); } else{   Serial.println("Problem reading channel. HTTP error code " + String(statusCode));  }  delay(15000); // No need to read the counter too often. }

Initializes the ThingSpeak library and network settings.

bool begin (client) // defaults to ThingSpeak.com

bool begin (client, port)

Always returns true. This does not validate the information passed in, or generate any calls to ThingSpeak.

Write a value to a single field in a ThingSpeak channel.

int writeField(channelNumber, field, value, writeAPIKey)

HTTP status code of 200 if successful. See Return Codes below for other possible return values.

Special characters will be automatically encoded by this method. See the note regarding special characters below.

Write a multi-field update. Call setField() for each of the fields you want to write first.

int writeFields (channelNumber, writeAPIKey)

HTTP status code of 200 if successful. See Return Codes below for other possible return values.

Special characters will be automatically encoded by this method. See the note regarding special characters below.

Write a raw POST to a ThingSpeak channel.

int writeRaw (channelNumber, postMessage, writeAPIKey)

HTTP status code of 200 if successful. See Return Codes below for other possible return values.

This method will not encode special characters in the post message. Use '%XX' URL encoding to send special characters. See the note regarding special characters below.

Set the value of a single field that will be part of a multi-field update.

int setField (field, value)

HTTP status code of 200 if successful. See Return Codes below for other possible return values.

Set the status of a multi-field update. Use status to provide additonal details when writing a channel update. Additionally, status can be used by the ThingTweet App to send a message to Twitter.

int setStatus (status)

HTTP status code of 200 if successful. See Return Codes below for other possible return values.

Set the latitude of a multi-field update.

int setLatitude(latitude)

HTTP status code of 200 if successful. See Return Codes below for other possible return values.

Set the longitude of a multi-field update.

int setLongitude (longitude)

HTTP status code of 200 if successful. See Return Codes below for other possible return values.

Set the elevation of a multi-field update.

int setElevation (elevation)

HTTP status code of 200 if successful. See Return Codes below for other possible return values.

Set the created-at date of a multi-field update. The timestamp string must be in the ISO 8601 format. Example "2017-01-12 13:22:54"

int setCreatedAt (createdAt)

HTTP status code of 200 if successful. See Return Codes below for other possible return values.

Timezones can be set using the timezone hour offset parameter. For example, a timestamp for Eastern Standard Time is: "2017-01-12 13:22:54-05". If no timezone hour offset parameter is used, UTC time is assumed.

Set the Twitter account and message to use for an update to be tweeted.

int setTwitterTweet(twitter, tweet)

HTTP status code of 200 if successful. See Return Codes below for other possible return values.

Prior to using this feature, a twitter account must be linked to your ThingSpeak account. To link your twitter account. login to ThingSpeak and go to Apps -> ThingTweet and click Link Twitter Account.

Read the latest string from a channel. Include the readAPIKey to read a private channel.

String readStringField (channelNumber, field, readAPIKey)

String readStringField (channelNumber, field)

Value read (UTF8 string), or empty string if there is an error.

Read the latest float from a channel. Include the readAPIKey to read a private channel.

float readFloatField (channelNumber, field, readAPIKey)

float readFloatField (channelNumber, field)

Value read, or 0 if the field is text or there is an error. Use getLastReadStatus() to get more specific information. Note that NAN, INFINITY, and -INFINITY are valid results.

Read the latest long from a channel. Include the readAPIKey to read a private channel.

long readLongField (channelNumber, field, readAPIKey)

long readLongField (channelNumber, field)

Value read, or 0 if the field is text or there is an error. Use getLastReadStatus() to get more specific information.

Read the latest int from a channel. Include the readAPIKey to read a private channel.

int readIntField (channelNumber, field, readAPIKey)

int readIntField (channelNumber, field)

Value read, or 0 if the field is text or there is an error. Use getLastReadStatus() to get more specific information. If the value returned is out of range for an int, the result is undefined.

Read the latest status from a channel. Include the readAPIKey to read a private channel.

String readStatus (channelNumber, readAPIKey)

String readStatus (channelNumber)

Returns the status field as a String.

Read the created-at timestamp associated with the latest update to a channel. Include the readAPIKey to read a private channel.

String readCreatedAt (channelNumber, readAPIKey)

String readCreatedAt (channelNumber)

| channelNumber | unsigned long | Channel number || readAPIKey | const char * | Read API key associated with the channel. If you share code with others, do not share this key |

Returns the created-at timestamp as a String.

Read a raw response from a channel. Include the readAPIKey to read a private channel.

String readRaw (channelNumber, URLSuffix, readAPIKey)

String readRaw(channelNumber, URLSuffix)

Returns the raw response from a HTTP request as a String.

Get the status of the previous read.

int getLastReadStatus ()

See Return Codes below for other possible return values.

Some characters require '%XX' style URL encoding before sending to ThingSpeak. The writeField() and writeFields() methods will perform the encoding automatically. The writeRaw() method will not.

Control characters, ASCII values 0 though 31, are not accepted by ThingSpeak and will be ignored. Extended ASCII characters with values above 127 will also be ignored.