I screwed up, and in error, I connected my usbasp programmer to a circuit containing an atmega328p Pro mini board that was running on two AA batteries.
The usbasp supplies voltage (5V) to the circuit.
There is an led on PD4 in the circuit. Cathode is connected to PD4, anode contains a 1K resistor to VCC. The led is always on as soon as power is applied.
The code no longer works. I even tried a simple blinky code, nothing is working. Funny thing, I can program it, it verifies, fuses are ok,
just code does not work and LED is always on.
I don't care about the $3 board, I would just like to know what could have happened to the mcu and how to prevent it in future.
(like maybe a protection circuit of some kind)
It is a big deal to remove the board, the circuit is very delicate and I would rather not if I can help it
or perhaps salvage the board. I know if I remove the board from the main board, I'll be replacing themain board or doing some trace patching!
Curious to know what happened.
Anyone have any ideas?