ThingSpeak (verified community library)

Summary

ThingSpeak Communication Library for Particle-based devices written by the ThingSpeak development team.

Example Build Testing

Library Read Me

This content is provided by the library maintainer and has not been validated or approved.

ThingSpeak Communication Library for Particle

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

ThingSpeak offers free data storage and analysis of time-stamped numeric or alphanumeric data. Users can access ThingSpeak by visiting https://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 this video 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. Visit https://www.mathworks.com/hardware-support/thingspeak.html to learn more.

Particle Web IDE

In the Particle Web IDE, click the libraries tab, find ThingSpeak, and choose "Include in App"

Compatible Hardware:

• Particle (Formally Spark) Core, Photon, Electron and P1.

Some Quick Examples

Write to a Channel Field

#include "ThingSpeak.h"

TCPClient client;

unsigned long myChannelNumber = 31461;    // change this to your channel number
const char * myWriteAPIKey = "LD79EOAAWRVYF04Y"; // change this to your channels write API key

void setup() {
ThingSpeak.begin(client);
}

void loop() {
// read the input on analog pin 0:
int sensorValue = analogRead(A0);

// Write to ThingSpeak, field 1, immediately
ThingSpeak.writeField(myChannelNumber, 1, sensorValue, myWriteAPIKey);
delay(20000); // ThingSpeak will only accept updates every 15 seconds.
}

Write to a Multiple Channel fields at once

#include "ThingSpeak.h"

TCPClient client;

unsigned long myChannelNumber = 31461;    // change this to your channel number
const char * myWriteAPIKey = "LD79EOAAWRVYF04Y"; // change this to your channel write API key

void setup() {
ThingSpeak.begin(client);
}

void loop(){
// read the input on analog pins 1, 2 and 3:
int sensorValue1 = analogRead(A1);
int sensorValue2 = analogRead(A2);
int sensorValue3 = analogRead(A3);

// set fields one at a time
ThingSpeak.setField(1,sensorValue1);
ThingSpeak.setField(2,sensorValue2);
ThingSpeak.setField(3,sensorValue3);

// set the status if over the threshold
if(sensorValue1 > 100){
ThingSpeak.setStatus("ALERT! HIGH VALUE");
}

// Write the fields that you've set all at once.
ThingSpeak.writeFields(myChannelNumber, myWriteAPIKey);

delay(20000); // ThingSpeak will only accept updates every 15 seconds.
}

Read from a Public Channel

#include "ThingSpeak.h"

TCPClient client;

unsigned long weatherStationChannelNumber = 12397;

void setup() {
ThingSpeak.begin(client);
}

void loop(){

// Read latest measurements from the weather station in Natick, MA
float temperature = ThingSpeak.readFloatField(weatherStationChannelNumber,4);
float humidity = ThingSpeak.readFloatField(weatherStationChannelNumber,3);

Particle.publish("thingspeak-weather", "Current weather conditions in Natick: ",60,PRIVATE);
Particle.publish("thingspeak-weather", String(temperature) + " degrees F, " + String(humidity) + "% humidity",60,PRIVATE);

delay(60000); // Note that the weather station only updates once a minute

}

Read from a Private Channel

#include "ThingSpeak.h"

TCPClient client;

unsigned long myChannelNumber = 31461;
const char * myReadAPIKey = "NKX4Z5JGO4M5I18A";

void setup() {
ThingSpeak.begin(client);
}

void loop(){

// Read the latest value from field 1 of channel 31461
float value = ThingSpeak.readFloatField(myChannelNumber, 1, myReadAPIKey);

Particle.publish("thingspeak-value", "Latest value is: " + String(value),60,PRIVATE);
delay(30000);

}

Documentation

begin

Initializes the ThingSpeak library and network settings.

bool begin (client)  // defaults to port 80

bool begin (client, port)

| port | unsigned int | Specific port number to use |

Returns

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

writeField

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

int writeField(channelNumber, field, value, writeAPIKey)

Returns

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

Remarks

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

writeFields

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

int writeFields (channelNumber, writeAPIKey)

Returns

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

Remarks

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

writeRaw

Write a raw POST to a ThingSpeak channel.

int writeRaw (channelNumber, postMessage, writeAPIKey)

Returns

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

Remarks

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.

setField

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

int setField (field, value)

Returns

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

setStatus

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)

Returns

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

setLatitude

Set the latitude of a multi-field update.

int setLatitude    (latitude)

Returns

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

setLongitude

Set the longitude of a multi-field update.

int setLongitude (longitude)

Returns

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

setElevation

Set the elevation of a multi-field update.

int setElevation (elevation)

Returns

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

setCreatedAt

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)

Returns

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

Remarks

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.

setTwitterTweet

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

int setTwitterTweet    (twitter, tweet)

Returns

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

Remarks

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.

readStringField

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

String readStringField (channelNumber, field, readAPIKey)

String readStringField (channelNumber, field)

Returns

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

readFloatField

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

float readFloatField (channelNumber, field, readAPIKey)

float readFloatField (channelNumber, field)

Returns

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.

readLongField

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

long readLongField (channelNumber, field, readAPIKey)

long readLongField (channelNumber, field)

Returns

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

readIntField

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

int readIntField (channelNumber, field, readAPIKey)

int readIntField (channelNumber, field)

Returns

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.

readStatus

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

String readStatus (channelNumber, readAPIKey)

String readStatus (channelNumber)

Returns

Returns the status field as a String.

String readCreatedAt()

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

Returns the created-at timestamp as a String.

readRaw

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

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

getLastReadStatus

Get the status of the previous read.

int getLastReadStatus ()

Returns

See Return Codes below for other possible return values.

Return Codes

Special Characters

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.

Additional Examples

The library source includes several examples to help you get started. These are accessible in ThingSpeak library section of the Particle Web IDE.

• CheerLights: Reads the latest CheerLights color on ThingSpeak, and sets an RGB LED.
• ReadLastTemperature: Reads the latest temperature from the public MathWorks weather station in Natick, MA on ThingSpeak.
• ReadPrivateChannel: Reads the latest voltage value from a private channel on ThingSpeak.
• ReadWeatherStation: Reads the latest weather data from the public MathWorks weather station in Natick, MA on ThingSpeak.
• WriteMultipleVoltages: Reads analog voltages from pins A1-A6 and writes them to the fields of a channel on ThingSpeak.
• WriteVoltage: Reads an analog voltage from pin 0, converts to a voltage, and writes it to a channel on ThingSpeak.

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