How to Use SIM800L to Send SMS and Control Relay by SMS

Introduction: How to Use SIM800L to Send SMS and Control Relay by SMS


This tutorial is showing how to use SIM800L to send sms and receive sms to control relay. SIM800L module is small in size and can be used to interface with Arduino to send sms, receive sms, call, receive call and else. In this tutorial, we only focus on send sms and control relay by receiving sms.


  • GPRS multi-slot class12 connectivity: max. 85.6kbps(down-load/up-load)
  • GPRS mobile station class B
  • Controlled by AT Command (3GPP TS 27.007, 27.005 and SIMCOM enhanced AT Commands)
  • Supports Real Time Clock
  • Supply voltage range 3.4V ~ 4.4V
  • Supports A-GPSSupports 3.0V to 5.0V logic level
  • Low power consumption, 1mA in sleep mode
  • Compact size 23mm x 35mm x 5.6mm

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Step 1: Material Preparation

Step 2: Follow the Video

Step 3: Source Code

Download source and click library SIM800L link:

  1. Library SIM800L: Adafruit FONA

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