Can I upload new programs onto a MEGA2560 through a serial port connected to pins 2&3? (through the correct RS232<->TTL level shifters)
I know the 16U2 chip acts as a USB->serial converter and it also asserting the reset which starts the bootloader running on the 2650. Does it do anything else?
As long as I can time the reset correctly, is there anything else preventing reprogramming directly through the RX/TX pins?
And if I do this, will the application program still be able to use the serial channel?