Programming the T-SIM7600G
Setup
7600x Github - I cloned this repo for easy access to the examples. git clone https://github.com/Xinyuan-LilyGO/T-SIM7600X.git
I already had the "ESP32 Dev" board installed on the Arduino IDE, but I had to install a couple libraries: TinyGSM and StreamDebugger, they were easily found through the library manager search.
Programming ESP32
I had to plug the USB-C cable into the TTL port (there are 2, one labeled USB and one TTL)
I set the baud rate to 115200 and left everything else default. I had to select the /dev/ttyACM1 device before getting the ATdebug.ino sketch to upload.
After setting the Serial Monitor to "115200" and to use "Both NL & CR", and pressing the RST button on the board, we were able to get an "OK" response!
AT Commands
Attach:SIM7500_SIM7600_Series_AT_Command_Manual_V3.00.pdf
I couldn't send the "ctrl-z" control character with the Arduino serial monitor, so I ended up struggling with minicom (it would've worked if I just unplugged/replugged the board), but I ended up compiling gtkterm. After that I was able to send the AT command to send a text message (after changing the mode: AT+CMGF=1)
Very cool