[avrdude-dev] EEPROM programming and page_erase

[Hannes Weisbach]

Hi everyone,

when testing some code for avrftdi I came across a problem with EEPROM 
programming: avrdude segfaults in avr.c:818 when calling pgm->page_erase (since 
avrftdi does not define that function).
If flash is programmed at the same time when the EEPROM is programmed, there is 
no problem, since a device erase is executed. Writing only EEPROM and using -e 
also works.

First, should that call not be protected by checking if the function-pointer is 
non-NULL? As far as I can tell it is an optional function.
Secondly, why is this function (page_erase) called at all? The devices I tested 
(Mega32 and PWM3B) do not have a "page erase" command for EEPROM. The 
datasheets state that EEPROM locations are erased when re-programmed: "An 
EEPROM memory location is first automatically erased before new data is 
written." (PWM3B datasheet, doc4317 p. 295).
pgm->page_erase() is called when auto_erase is true (avr.c:818). I would call 
the behaviour of the EEPROM of the M32 and PWM3B "auto erase". Maybe this is a 
mistake and should be if(!auto_erase)?

I would appreciate any comments.

Best regards,
Hannes