I’m having issues with atmega 328p-au (arduino nano). I created a custom board using an ADC and the micro controller, flashed a new boot loader and programmed it successfully. Then I tried to upload an sketch which scans for I2C devices to check if my ADC is being recognized. half of the time it managed to find it, but failed the other half. I realized the RESET pin of the ADC is controlled by the arduino and that’s what’s causing the issue, so I added a single line of code to pull that pin high. That’s where all hell broke loose!
After finishing upload, I opened the serial monitor and instead of the messages I was expecting, I was met with a bunch of gibberish … I checked the baud rate and it was correct.I tried re uploading the code but to my surprise, that failed too! I dropped the baudrate from 115200 to 9600 and this time it worked! but the output was still junk! I thought I might have killed the chip so I replaced it, but it’s still the same issue with the new chip as well. I washed the board with 70% alcohol and let it dry, tried checking for shorts, etc but still no luck! does anybody know why my serial communication is broken? how can I troubleshoot this issue?
I attached a picture of the output.