No Serial Response SIM800c (Arduino Mega)

Projects Networking, Protocols, and Devices
1

Hey People,

I recently bought a SIM800c Model with integrated level shifter (as far as I know), see attachment.

I can start it up but I can establish no Serial connection (I don't get an answer when i send 'AT', NR and CR are enabled in the serial monitor).
Pins are connected as follows:
SIM800 5v -> 5v/3a Power supply
SIM800 V_TLL -> 5v Arduino
SIM800 GND -> GND Arduino & GND Power supply
SIM800 TX -> Pin 19 (RX1) Arduino
SIM800 RY -> Pin 18 (TX1) Arduino
There is a german e-plus simcard with simlock disabled inserted.

My code:

void setup()
{
  Serial.begin(9600);
  
  Serial1.begin(9600);

  delay(1000);
  Serial.println("Testing GSM SIM800L");
}

void loop()
{                
  if(Serial1.available())
  {
    Serial.write(Serial1.read());
  }
  if(Serial.available())
  {    
    Serial1.write(Serial.read());
  }
}

I am out of ideas and searching the forums and the rest of the internet didn't give me any concrete answers, as to what is going wrong.

I would really apprechiate some help!

IMG_1168.JPG

2

I'd try swapping TX and RX again, just to be sure

3

Swapped it more times than i can count. Stumbled onto this though: Hardware build | Details | Hackaday.io Will try that out first thing tomorrow. Might break the module, but I'm out of options anyway