4/23/2024 0 Comments Arduino mega 2560 reset pinLooking at the rest of the first (and only) message, it says "AVRISP_2" so I would expect to find this string within the dumped Flash, but I don't find it? Anyone familiar with the bootloader for Mega? The dumped flash looks like this where (I believe) the bootloader area begins: 0003e000: 0d94 89f1 0d94 b2f1 0d94 b2f1 0d94 b2f1. This probably makes avrdude disregarding the reply. Each communication sequence (according to the STK500v2 format) should start with 0x1B (dec 27), but the non-working Mega sends 0x19 for some reason. The odd thing is that it appears to be a communication problem from the Mega. Still get the problem with the non-working Mega. So, the non-working Mega should have exactly the same flash content as the working one. Both 256 kiB files compare with no differences. Finally, read the flash from the updated, non-working, Mega. Addition: I read the FLASH from the working Mega and wrote to the non-working Mega using avrdudess and an AVR ISP mkII. ![]() No, the bootloader - or something - is definitely there. Using AtmelStudio I have copied Flash, EEPROM, Fuses and lock bits from the working board to the one that isn't - still same result, can't program using the USB. Programming the board using an AVR ISP mkII works however perfectly well. Have trired to press reset manually with no result. I get the "avrdude: stk500v2_ReceiveMessage(): timeout". Programming the unit is however impossible using the USB port. When trying to program the board using USB, I see the same kind of reset signal on both the working and not working board (measured at the reset switch - DC block cap from CH340 is working). I have also verified this on an oscilloscope. ![]() When connecting a terminal, the arduino resets as expected so also reset is working. Serial port is working (at least at 115200 bps) - can send and receive characters using a simple sketch. One of the units works as expected and can be programmed through USB. A while ago I bought two Arduino MEGA2560 on ebay. Hello, I have come across a very odd problem - or so it seems.
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