I've been searching for how to connect a SIM7100A module to an Arduino (Uno or Mega), but I haven't been able to find any posts anywhere, nor videos nor any kind of documentation that shows how to do it. Does anyone here know how to connect it so I can send simple AT commands to the module from the Arduino? (I just want to make GET requests and get GPS coordinates)
Got it to work, in part thanks to the documentation that @Juraj posted. My pinout is the following, in case anyone needs it:
SIM7100A -> Arduino Mega
SUPPLY -> 5V (the SIM7100A's SUPPLY pin powers the actual board, it's different from the VDD pin which is only for the Serial communication)
GND (both lower & upper) -> GND
VDD -> 3.3V
TXD -> RXD2
RXD -> voltage divider (5V to 3.3V) -> TXD2
Once the module is powered (the PWR LED is on), you gotta press the module's reset button for about 3 seconds and then wait for the NET and STA LEDs to turn on, then you can start sending AT commands to it.
I don't know if this will be the case for everyone, but for me, the serial communication through the SIM's USB debug port is with 9600 bauds, but the communication through the TXD and RXD pins is with 115200 bauds.