how to write AVrdude configuration file ?

[chrischris]

Hi there ,
I have posted thsi question in AVR forum but seems that nobody is using it, so I am posting it here, I am trying to add support for ATmega8U2 in AVRdude and for that I have to edit configuration file of avrdude, I have understood everything about how to do it except for one thing, in avrdude configuration file, for each AVR MCU there is somethign defined as readback_p1 and readback_p2 for EEPROM and FLASH, can anyone tell me what is it ? and how can I findd it in the datasheet of ATmega8U2 ? On edaboard forum I found that it is the hardware ID for the device but, I dont know where to look for it in datasheet , and why it is different for FLASH and EEPROM of the same device ? For ATmega8 the configuration of avrdude goes like this with readback_p1 and readbackp2


EEPROM

readback_p1 = 0xff
readback_p2 =0xff


FLASH

readback_p1 = 0x00
readback_p2 = 0xff



Please anybody explain to me what is this readback ?


Thanks,
Chris