oric_dan:
Ok, here is some progress. I tried lefty's sketch, with arraysize set = 4000 to 7000.
I uploaded a dozen or so times, using both the FTDI Friend and the FTDI cable, and
it never failed to burn and verify properly. I still have the RX0 wirewrap wire
running inbetween the xtal pins, and no low-pass filter on the RX0 pin.arraysize = 4000 gives a 67808 byte file, and 7000 gives 115808 bytes. Upload and
verify takes 70-sec for the 115808 byte file.One thing of interest - for arraysize > 4000 or so, the sketch no longer works correctly,
ie Led 13 does not flash after uploading. At 4000 and below, Led 13 blinks ok.
Yes, that is a problem, and it's very likely that the sketch is not being loaded correctly after a certain size is reached even though it's less then maximum flash memory size. There is no AVRDUDE error reported after the upload, but obviously the blink program is not running after the upload. It's believed to be a bug in the bootloaders for large (but still legally sized) sketches. For instance when using the Uno's bootloader one can load up a sketch right up to near the flash memory maximum size limit, but with a mega1280 I can't even get close to near max size. Coding Badly is of the opinion that is a bug in older bootloaders and their interaction with AVRDUDE on large code size uploads. So if the 1284P bootloader is just a recompilation based on one of the older mega bootloader programs it may have 'inherited' the same problem. This should be investigated further but I'm afraid I'm not knowledgeable enough in software/bootloaders to be a direct help other then testing.
I guess a first step is for someone to try a different method to developing large sketch sizes just to make sure it's not my sketch causing the problem symptom. Anyone up for the challenge?
Lefty