I bought Gboard module with Atmega328P inside: https://wiki.iteadstudio.com/Gboard
I don't want to use Arduino at all. I just want to upload my own code into Atmega328P and make a phone calls without external devices. The problem is GBoard works in 3,3V level but I want to upload my software with 5V USBasp (Barion copmany, V2 of USBasp). There is a jumper to work with USB 5V OR not to supply the device that is programmed. I want to supply my programmed Atmega328P with 5V so the jumper is on.
There are ISP pins available in GBoard but is it safe to connect my USBasp?
- Once I connect my USBasp there will be 5V in the output of GBoard ASM1117 voltage regulator (in the output pin; is reverse voltage safe?).
- Once I connect my USBasp there will be 5V in the LED with 1k resistor.
- Will it break my SIM900 module? In general there is no direct connection with power supply of SIM900. Could anyone advise?