Reads from eeprom and flash take a normal amount of time. Maybe 20s for flash and a few seconds for eeprom.
I did have to fix the bootloader on the atmega2560 using an arduino uno board. Maybe I introduced an error in that process (wrong bootloader uploaded for example). //------- +*†*+ ------- ȌȔȕȍȕȕȍ Shane Santner Founder and President, roundup2roundup <http://twochristiansandagrill.blogspot.com/> Embedded RE @ blackowl <http://blackowlre.com/> On Thu, Sep 16, 2021 at 10:27 AM Andy Bennett <andy...@ashurst.eu.org> wrote: > Hi, > > > I have a mega2560 R3 arduino board. I created a simple sketch > > from the Arduino > > IDE from file->Examples->EEPROM->eeprom_clear and then modified it to > write > > 0x00112233445566778899aabbccddeeff repeating to the eeprom memory. After > > writing out these values and then using avrdude to read them back I get > > 0x00112233445566770011223344556677 instead. I have a custom programmer > that > > read back the expected values correctly. > > > > The avrdude command I am using for reading out the eeprom is: > > avrdude -p atmega2560 -c wiring -P COM4 -b115200 -U eeprom:r:dump.bin > > I had a similar problem reading/writing from/to a Mega2560 R3 Arduino > board > with a JTAG3ICE in ISP mode. I managed to read the fuses, flash and eeprom > but couldn't write them reliably. > > I managed to flash the arduino bootloader reliably and then flashed the > rest using that. > > The ISP was also very slow, taking ~20 minutes to read or write the image > from/to flash (which was > 200KiB large). > > > I'm not sure if there is a problem with these boards. My searching was > inconclusive as not many people seem to post about using the ISP header > and > lots of people who have this problem solved it by reflashing the > bootloader. > > I tried powering it through the power jack rather than the USB port but > that didn't seem to help. > > > > How long do your EEPROM reads and writes take? > > > > > Best wishes, > @ndy > > -- > andy...@ashurst.eu.org > http://www.ashurst.eu.org/ > 0x7EBA75FF > >
