[avrdude-dev] Load Extended Address command and word/byte programming issues

[Hannes Weisbach]

Hello,

I'm currently streamlining avrftdi's paged load and write functions. In the 
process, I adapt them to the new avrdude interface for paged load and write. 
However, I stumbled across some issues I'm not entirely clear about.

1) Does avrdude take care of issuing a load extended address command? Because 
page programming is now done page-by-page avrdude "knows" when the 128k 
boundary is crossed and could issue a load extended address command. is this 
the case?

2) If the programmer has to issue the load extended address command: Does the 
command need to be issued _exactly_ once, or can it be issued multiple times? 
For example, before loading a page with an address greater 128k, is it "safe" 
for the programmer to send the command before loading the page. This would slow 
down the programming time noticeably, but simplify the programmer code a lot.

3) It seems to me, today all AVRs are programmed word-by-word, and a word being 
2 bytes wide. Is this correct? Code in avr.c:373 suggests that there are AVRs 
which use word-addressing and others which use byte-addressing to program the 
memory. avrftdi now only supports word-addressable memory (in paged mode). Is 
byte-programming still used or do all "modern" AVRs use word-addressing?

Best regards,
Hannes