I am connecting Sim800l to arduino uno. Using rechargeable battery about 4V. The Sim800l cannot connect to the network. I have connected the Sim800l ground, TX, RX, and VCC pins. Nothing else is connected. Added two Sims in two different countries. Anyone used it before and successfully send an SMS?

 

Welcome to AAC.

The SIM800L can only connect to 3G or lesser mobile systems. In many countries this is no longer available.

Are you sure that you have a 3G system to connect to?

 

I have asked the GSM, they say the sim works as 2G.

 

I didn't add any resistors as recommended. Could that affect connection?

 

I didn't add any resistors as recommended. Could that affect connection?

Which resistors? Are you using a breakout board, if so, which one?

 

I read that RX need to recieve 3.3V while Aurduino Uno transmit it's TX using 5V so Between Sim800l RX and Arduino TX a resistant should be applied.

 

Unfortunately, if you connected the 5V TXD from an Arduino to the RXD of the SIM800, you may have damaged the module.

The right way to do it is using a level shifter. But if you’ve already tried to send data at 5V, you may have a deaf module now.

 

Oh. Maybe that's why. Thanks.

 

This is an excellent tutorial which should answer most of your questions, also points out the mentioned problem with sending 5V on the TX line from the Arduino to the module:

https://lastminuteengineers.com/sim800l-gsm-module-arduino-tutorial/

So I would say follow this step by step, and if you still have problems, please first show us your wiring diagram. Even if you are using a battery for the module and other 5V supply for the Arduino, their GND's must be connected in common.

 

Than

This is an excellent tutorial which should answer most of your questions, also points out the mentioned problem with sending 5V on the TX line from the Arduino to the module:

https://lastminuteengineers.com/sim800l-gsm-module-arduino-tutorial/

So I would say follow this step by step, and if you still have problems, please first show us your wiring diagram. Even if you are using a battery for the module and other 5V supply for the Arduino, their GND's must be connected in common.

Thank you so much. I will.