SIM800L module not responsive

Using Arduino Networking, Protocols, and Devices
1

Hello,

Newbie here! Recently I have started using Arduino Uno for a school project which involves using an SIM800L module for sending SMS.

This is the module: Nettigo: SIM800L GSM / GRPS module

I have tried many tutorials, unfortunately none of them worked. After watching some video tutorials I realized that my module's LED indicator has never been on, whereas the module in all the videos would blink continuously once it's connected to power.

The wiring:

  • VCC to a 3.7V Lipo battery (actually 4.2V when I measured)
  • RX to pin 11
  • TX to pin 10
  • GND to ground

Code: from GSM SIM800L Sheild with Arduino - Tutorials

#include <SoftwareSerial.h>

String Arsp, Grsp;
SoftwareSerial gsm(10, 11); // RX, TX

void setup() {
  // put your setup code here, to run once:

  Serial.begin(9600);
  Serial.println("Testing GSM SIM800L");
  gsm.begin(4800);

}

void loop() {
  // put your main code here, to run repeatedly:

  if(gsm.available())
  {
    Grsp = gsm.readString();
    Serial.println(Grsp);
  }

  if(Serial.available())
  {
    Arsp = Serial.readString();
    gsm.println(Arsp);
  }

}

This piece of code doesn't print anything when I type "AT" in console.

Does the SIM800L need a specific method to be turned on?
Could it be possible that the module is already broken?
(I have seen its red LED flash for a quick moment while testing some other things, but for most of the time the LED is never on.)

Any help would be much appreciated!

Thank you!

2

For a device that responds to AT commands, it is usually a good idea to debug it first with a terminal program such as Putty before bringing in an Arduino.

You'll need a USB-TTL adapter.

Send AT commands and receive the response.

3

Hello, thank you for your response!

A little update, I have made some changes, the phone module is now properly powered and seems to be connected to network (red LED blinks at every 3 seconds). However the module is still not responding to AT commands. Using the same code as above, the SoftwareSerial never becomes available, so my "AT"s are always unanswered.

The wiring now includes a level shifter between the SIM800L and Arduino, with 5V connected to HV, 2.8V to LV, SIM800L's TX and RX-->low side of level shifter-->Arduino pins(10 and 11 respectively). I have also connected both the module's and Arduino's ground together.

The AT command is made using serial console, with both NL & CR.

Thank you!

sim800l_connection.png
sim800l_connection.png819×460 3.96 KB

4

Completely ignored my advice about using a Terminal program with USB-TTL adapter to debug.

I am out of here.