Fixed hfuse for mega 2560.

Optiboot / optiboot

Small and Fast Bootloader for Arduino and other Atmel AVR chips

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Fixed hfuse for mega 2560. #271

Closed ZsoltSaskovy closed 5 years ago

ZsoltSaskovy commented 5 years ago

According to the comment in the makefile 1k bootsize should be set, but 0xDE means 4k.

See http://eleccelerator.com/fusecalc/fusecalc.php?chip=atmega2560&LOW=F7&HIGH=DC&EXTENDED=FD&LOCKBIT=FF for further reference

WestfW commented 5 years ago

Both your fusecalc and the one I use say that 0xde is 512words (1024bytes), which is correct. 0xdc would be 1024 words. 4K words would be 0xF8... Beware “set” vs “1” - on AVR, you set a fuse by programming it to zero...

ZsoltSaskovy commented 5 years ago

Woot,you are right. 512 WORDS, not bytes. Let me ask just one more question before declineing the PR: why did you choose 0xF7 for lfuse? I'm asking because where ever I was looking for the default value it's said to be 0xFF.