Upload Error [solved]

[DonpK]

I am suddenly unable to upload any sketch to a Moteino MEGA USB which previously was working fine.

I've surveyed similar problems elsewhere on the Forum and none of suggestions help - I've swapped USB cables and ports to no avail. The USB cable and port uploads fine to other Moteino boards.

Oddly, the problem started after I tried to upload a sketch I had divided into multiple tabs. It compiles fine, but won't upload. This is the first time I'd tried that approach, although it's hard to see any connection. I can see the TX and RX LEDs flashing, but I get this error:

       Using Port                    : COM3
         Using Programmer              : arduino
         Overriding Baud Rate          : 115200
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x52

until it finally times out. 

The last sketch I successfully uploaded is still running okay - it's communicating successfully with another Moteino node. This would seem to indicated that the Moteino MEGA board itself is operating normally. I just can't upload any sketches - includiing the basic blink.ino - to the MEGA.
Any suggestions?

[Felix]

Does the board serial/COM port show up normally (no "Unrecognized device" or similar errors)?
Do you have another identical board that uploads OK on that same computer?

[DonpK]

Does the board serial/COM port show up normally (no "Unrecognized device" or similar errors)?

Yes, as indicated in the portion of the error message shown in my message,
 Using Port                    : COM3
         Using Programmer              : arduino

Do you have another identical board that uploads OK on that same computer?

Yes, I tried uploading blink.ino to another Moteino MEGA USB and the upload worked fine.

Here's a portion of that MEGA's successful upload message:

         Using Port                    : COM13
         Using Programmer              : arduino
         Overriding Baud Rate          : 115200
         AVR Part                      : ATmega1284P

[DonpK]

I believe I found the problem. I recently added a RTC to the project I'm using that MEGA for. I connected the alarm output of the RTC to MEGA pin D8. This pin is also used for RX0 for the Serial 0 which is used by the FTDI/USB connection. When I removed the RTC alarm connection to D8, the upload problem went away.

I didn't have the upload problem when I was uploading the sketch including the RTC code module. However, when I was trying the multi-tab version of the sketch, the RTC section wasn't included.

[Felix]

Thanks a lot for the update, that explains it!