Experimenting with a USBasploader type bootloader for a standalone 2561 project but testing on an Arduino MEGA.
Avrdude version 6.3 (from platformio), Mac OS-X 10.13.6, programmer is Olimex stk500v2 (DB25 back shell, LED but no push button).
No connection problems and programs reliably. Problem is what is actually programmed and read back.
While testing the bootloader I noticed it appeared twice in th the 256k address space, where it should be at the top, and again at about 128k.
Created a 256k random intel hex format file and wrote it, it writes but verify fails.
Reading the flash back and comparing it to what was written is odd. The first 64k byte block is correct, second 64k block doesn't match, third 64k block is correct, fourth 64k block doesn't match but is same as the second block. The two identical bad blocks don't match any of the write file blocks.
What is going on, is it the programmer, is it avrdude or its conf?
Hope to learn a bit more on the weekend when I can borrow a 'real' avr programmer.
Any assistance apprecicated.