I have a SIM800L module (green board). I used this to test my module.

In that page, it use a SIM800L red board with a 3.7v LiPo battery. But I directly connected 5v from the Uno to the module.

  • GND >>> GND
  • RX 10 >>> TX
  • TX 11 >>> RX
  • 5v >>> Vin

I see "Message Sent Successfully!" message in COM window but nothing happened.

I can not find the problem.

The SIM800L module (green board) specification is here.

The SIM800L module (red-green-blue boards) is here.

| improve this question | | | | |

I used a Power Supply and tested the board and SIM800L with it.

At the beginning, the SIM800L only uses a max of 100mA (V = 5v) and after finding the network only 10mA. In this situation the message is sent. I tested it with 4.2v but no message was sent.

It seems it needs 5v to be applied. The 5v of the Uno will be reduced to reach the SIM800L and so no message is sent.

| improve this answer | | | | |

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.