Hello everyone!
I want to make a small project and I want to send text messages with my arduino. I bought a small SIM800L board but I have a weird problem.
This is the board I use, and I connected it to my arduino via SoftwareSerial. The arduino just acts as a pass trough between the module and the Arduino serial window.
So I first check if there is a connection by sending "AT", this works fine. Before I can do anything I have to set the password, to check that I send "AT+CPIN?". The module answers this with "SIM PIN", that means I indeed need to enter the pin first. I can do that by putting in this "AT+CPIN="1111". The module accepts this and sends a confirmation that the pin is correct and I am ready to go. Here is what I see.
AT
OK
AT+CPIN?
+CPIN: SIM PIN
OK
AT+CPIN="1111"
OK
+CPIN: READY
Call Ready
SMS Ready
But when I check again with the pin, it says it needs to be entered. This and a few things I have tried show that the module resets itself. This is another thing that shows this, when I enable more informative errors, instead of sending just ERROR, it sends why. I enabled that and after entering the pin, that was disabled again. Which means the module resets itself.
The first thing I tought it was a power issue, but there is little to no drop in voltage and the current is max 140mA and my supply can handle 2A.
Does anyone here has experienced this before or knows what the problem is?
Thanks in advance! 
Grtz,
Thomas
