Arduino - Send SMS Message

In this tutorial we are going to learn how to use Arduino to send SMS message.

There are serveral ways to send SMS message from Arduino:

This tutorial uses IFTTT to send SMS message. The code is available for Arduino Ethernet Shield 2 or PHPoC WiFi/Ethernet Shield.

※ NOTE THAT:

Sending SMS message via IFTTT only works on Android phone and The Android phone must be connected to Internet.

Hardware Required

1×Arduino UNO or Genuino UNO
1×USB 2.0 cable type A/B
1×Arduino Ethernet Shield 2
1×Ethernet Cable

OR

1×Arduino UNO or Genuino UNO
1×USB 2.0 cable type A/B
1×PHPoC WiFi/Ethernet Shield
1×(optional)Ethernet Cable
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Prerequisite

If you do not know about IFTTT and related concepts, We highly recommend you reading the following tutorials:

Wiring Diagram

  • Arduino - Ethernet Shield 2: we just need to stack the shield on Arduino Uno/Mega
  • Arduino - Ethernet Shield 2
  • Arduino - PHPoC Shield: we just need to stack the shield on Arduino Uno/Mega
  • Arduino - PHPoC Shield 2

How It Works

We need to:

  • Install IFTTT app from Google Play Store on Android phone. IFTTT service which runs on the background is also installed.
  • Create an IFTTT Applet on the IFTTT website, which connects Webhooks to SMS service.

When we create the Applet:

  • We can specify the phone number we want to send the SMS message to.
  • We can write the content of the SMS message to be sent.
  • We can include data from Arduino to the content of SMS message.

※ NOTE THAT:

The content of the SMS message is specified on the Applet, not in the Arduino code.

Workflow

  • Arduino makes an HTTP request to Webhooks of IFTTT,
  • Webhooks triggers SMS service on IFTTT
  • SMS service on IFTTT sends a command to IFTTT service on your Android phone.
  • IFTTT service on your Android phone sends an SMS from your Android device to any phone number you specify.

How To Use IFTTT with Arduino

  • Install IFTTT app from Google Play Store on Android phone
  • Create an IFTTT account and Login to IFTTT.
  • Create an Applet of Webhooks and SMS services. Please write down the event name we uses
  • After creating the applet, get Webhooks key from IFTTT.
  • Copy below Arduino code and paste in Arduino IDE.
  • Replace event name and Webhooks key in the Arduino code
  • Upload the code to Arduino

※ NOTE THAT:

  • The event name is given by you. You can give any name.
    • Webhooks key is created by IFTTT. You can not change it.

See the video tutorial at the end of this tutorial.

Arduino code

Arduino IFTTT code for Arduino Uno/Mega with Ethernet Shield 2

/* * Created by ArduinoGetStarted.com * * This example code is in the public domain * * Tutorial page: https://arduinogetstarted.com/tutorials/arduino-send-sms-message */

Arduino IFTTT code for Arduino Uno/Mega with PHPoC Shield

/* * Created by ArduinoGetStarted.com * * This example code is in the public domain * * Tutorial page: https://arduinogetstarted.com/tutorials/arduino-send-sms-message */

※ NOTE THAT:

This tutorial used the dynamic IP address (via DHCP). If you want to use the static IP address:

Result

In the two above codes, If succeeded,

  • The result in Serial Monitor looks like below:
  • COM6
    Send
    Connected to server HTTP/1.1 200 OK Date: Thu, 14 May 2020 07:06:40 GMT Content-Type: text/html; charset=utf-8 Content-Length: 44 Connection: close X-Top-SecreTTT: VG9vIGVhc3k/IElmIHlvdSBjYW4gcmVhZCB0a== ETag: W/"2c-4f52ca3d" Server: web_server Congratulations! You've fired the test event disconnected
    Autoscroll Show timestamp
    Clear output
    9600 baud  
    Newline  
  • You receives an SMS message
  • Arduino SMS message receive

Video Tutorial

How to Include Sensor Data to SMS Content

To include data from Arduino to SMS content, we need to do:

  • In Arduino: Include data into HTTP request (in the query string).
  • In Applet: modify the setting to extract data from the HTTP request.

You can learn what is query string in this tutorial

There are 5 variables we can use in the setting of the IFTTT Applet.

{{EventName}} Extracted from HTTP request
{{OccurredAt}} System time when event occurs
{{Value1}} Extracted from the variable value1 of query string in HTTP request
{{Value2}} Extracted from the variable value2 of query string in HTTP request
{{Value3}} Extracted from the variable value3 of query string in HTTP request

For example:

  • In Arduino: Change String queryString = "" to String queryString = "?value1=26&value2=70" in above codes.
  • In Applet: Modify the content of SMS message in the setting of the IFTTT Applet as follow:

Hi guy,


This is Arduino Uno, I would like to inform you that:

- The outside temperature is {{Value1}} °C

- The outside humidity is {{Value2}} %


All the above value is measured at {{OccurredAt}}


Good luck and stay healthy!

In the above message, "
" make new line when displaying.

The SMS message will be like below:

Arduino  SMS message content

You can read the temperature and humidity from sensor and put in the query string. See how to include data from sensor to query string

Challenge Yourself

Based on the above code, make the following project:

  • Send an SMS message when the button is pressed
  • Send an SMS message when the door is open
  • Send an SMS message when the temperature is too hot ...

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