Optiboot Atmega2560 Issue

hi all,

i have been trying use optiboot(https://github.com/majekw/optiboot/tree/m2560/optiboot) atmega 2560. know bootloader writing flash application, use upload sketches stk500 v1protocol.

i have burned bootloader mega2560 using atmel ice, boot loader burned successfully. have changed fuse bit

bootsz 4096w_1f000 1024_1fc00.
bootrst still set 1

observation 1:

arduino ide board type selected optiboot on mega2560, uses stk500 v1 on com port , able upload sketch. there verification error , sketch doesn't load after finish writing(avrdude using command line avrdude -cc:\arduino-1.6.7\hardware\tools\avr/etc/avrdude.conf -v -patmega2560 -carduino -pcom13 -b115200 -d -uflash:w:c:\users\sumanth\appdata\local\temp\build4fc144f385b06dee29b5212dbaa60d2b.tmp/presenece.ino.hex:i).

avrdude: verification error, first mismatch @ byte 0x0003
         0xc1 != 0x00

i using avrdude 6.2 write suggested change @ http://savannah.nongnu.org/bugs/?40897.

i couldn't understand why sketch not loading , verification error.

observation 2:

i compiled sketch ide , took [sketchname].with_bootloader.hex temp folder , used atmel ice write concatenated application , bootloader hex file. after successfull writing flash.

this loaded sketch correctly.

any inputs appreciated. thanks

the stk500v1 protocol used optiboot not allow more 128kbytes of code.
except stk500v1 used large devices anyway, using "raw spi command" feature of protocol change high byte of uploaded address.
however, optiboot stripped down minimum size, , not support "raw spi command" feature.

therefore, can't use optiboot on atmega2560, though works on atmega1280.

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