Hi, I am having some problems with my arduino and was hoping someone could help me as I have already tried everything I can think of. When trying to upload a sketch I always receive the error code "avrdude: stk500_getsync(): not in sync: resp=0x00".
This started after I had uploaded a modified version of Mike Stirling's flashrom programmer which was compiled and uploaded to the arduino manually. Things I have tried so far include:
1: I tried three separate computers with a combination of known working cables, all fail to upload sketches. I can distinctly see where before uploading the board reboots (indicated by the L led flashing 3 times) and then the Rx led flashes another 3 times before it gives the error.
I then went on to trying a loop back test. This failed, I could again see the Rx Led on the Arduino blinking but the Tx led stays off.
The next thing i tried was re-uploaded the Uno's bootloader, via the IDE using a parallel programmer thinking I had over-written it when i uploaded the previous program.
Still being unable to upload through the IDE I uploaded a slightly modified "blink" sketch using the programmer to see if the ATmega328 was still functional. This worked and I reloaded the bootloader after this test.
Thinking that the problem had to be the atmega16u2 I downloaded flip and uploaded the "Arduino-usbserial-atmega16u2-Uno-Rev3.hex" firmware. This produced no change.
I then reloaded the "Arduino-COMBINED-dfu-usbserial-atmega16u2-Uno-Rev3.hex" as per this thread via the parallel programmer with the following command:
avrdude -c dapa -p m16u2 -P /dev/parport0 -v -e -U flash:w:Arduino-COMBINED-dfu-usbserial-atmega16u2-Uno-Rev3.hex:i -U lfuse:w:0xEF:m -U hfuse:w:0xD9:m -U efuse:w:0xF4:m -U lock:w:0x0f:m
This again made no change.
I again tried the loopback test shorting the Rx and Tx just ahead of the resistor pack as suggested here. This worked and I received the exact string I had typed.
This led me to believe that both the Atmega16u2 and 328p are working correctly but there is some problem in the communication between each. I then used my DMM to attempt a continuity test between the points referred to above and the Tx and Rx breakout points as well as pins 31 and 30 on the Atmega328p. Each test returned a resistance of 1.03k which is the same as the resistance of the resistor itself.
At this point I am unable to think of what could possibly be wrong. Can someone with a bit more knowledge on this topic give me a bit of advise please? I am in the process of ordering another Arduino but I would really like to see if i could learn why this failed and recover it if possible.
Edit: I should mention that the board is a Make Special edition SMD version and so I was unable to test it with the mega328p removed, the best I could achieve was to try it with the reset and gnd pins connected and also another time with the reset button held down.