Hi All,
I'm got something funny going on with a atmega 2560 board that I have made.
It has exactly the same layout and circuitry as a previous board which works fine, however:
I programmed the bootloader with the standard Arduino bootloader file, set fuses etc and it successfully programs and sets fuses.
However, when I try and program it using UART (I am using a USB to TTL converter) it cannot see the atmega and I get a timeout error.
I have tried reburning the bootloader and checked connections multiple times and it doesnt work.
Even though the ttl adaptor works on the original board, I have done a loopback test to confirm it works okay.
I have used a continuity tester to check the reset circuit, the RX and TX and all is good. I have also added a 0.1uf capacitor from the DTR pin on the TTL adaptor, with the negative going to the reset pin on the atmega.
Still no joy!
Any ideas please folks?