[avrdude-dev] ATmega256x support started

[Joerg Wunsch]

I started to implement ATmega256x support.

The major challenge here is that the current 16-bit addressing no
longer suffices, and the ATmega256x deploys an "Load extended address"
instruction to supply the high bit(s) of the address.  Thus, the
config syntax and the individual programming algorithms had to be
touched.

Implemented so far:

. new keyword "load_ext_addr" in config file
. config file entries
. jtag2 works out of the box as it doesn't use ISP commands
. jtag1 doesn't support it anyway
. the generic implementation used by the bit-bang backends
  has been done; it's quite slow in particular when reading,
  perhaps the high address bit(s) should be cached, and the
  load extended address command only issued when needed

Not implemented yet:

. stk500v2 adaptations
. stk500[v1] and stk500 probably don't support the chip anyway
. avr910/butterfly?

As I'm going to leave for vacation by end of the week, I'm not sure
whether I can do anything on the open items before that.  If at all,
it'll very likely be stk500v2 then.

-- 
cheers, J"org               .-.-.   --... ...--   -.. .  DL8DTL

http://www.sax.de/~joerg/                        NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)