Introduction: An SMS Remote Control

About: I'm a french student in Toulouse ! I like to 3D print things and make programming projects

This project proposes a way to secure your thing. The final result of the project is a switch commanded by an SMS. So you can adapt this to your project. The program integrated authorized phone number and the user need to enter the good "password" to open something.

I'm a french student, so I try to do my best to make everything "English"

Step 1: List of Materials

You will need :

  • A SIM800L module
  • A SIM micro card
  • An Arduino Uno
  • Wires
  • 1 10KOhm resistor
  • 1 20KOhm resistor
  • A 2N2222 transistor
  • A 1S lithium battery

Step 2: Prepare the SIM800L Module

This module is cool because he's cheap but he works on 3.3V logic. Also, when making some special event, i use a lot of battery (more than 1A). So A COMPUTER CAN NOT FEED THIS MODULE. Use a battery and wire the module according to the picture (I use the configuration of this website ; he presents also how to make or receive calls with this same module).

I insist but if you don't respect this wiring, it will not working.

Them, you can insert the Micro-SIM like the picture. But before, delete our PIN code because a PIN code and my programwon't work together. You will need to add lines to the code.

To know if the sim800L working, check the yellow led. If she'is blinking every 2/3s. It's good, your SIM is registered on the network. If you got it, we can go on the next step. if not try to go outside or check the battery and the wiring.

Step 3: The Main Code

The code is presented like this

  • A first setup part in which the SIM800L is put in mode receive SMS
  • A loop who check if their are new message
    • we look if the phone number is known
    • we look if the message contain the password
      • if yes, we open
      • if not, try again

In the top of the program, you can modify the authorized numbers and how many do you want. You can also modify the password.

Step 4: Have Fun

The code will activate a transistor for a few time. This one can replace a pushbutton in a remote. In this way, you can place this transistor in a portal remote and simply send an sms to your portal. For my case, I first install an LED to see if everything works, then I will open my garage with this.

I hope everything work. If not contact me at