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

[Joerg Wunsch]

As Hannes Weisbach wrote:

> My understanding so far is, that the load extended address command
> has to be issued when a page with an address >= 128kiB has to be
> programmed and the page programmed before had an address <128kiB. Is
> this correct?

Yes, I think it is.  (But the usual disclaimer: we don't have access
to the firmware sourcecode, so you cannot be 100 % sure.)

> The STK500v2 initialises last_addr to UINT_MAX, so it seems to me,
> it is signaled to the programmer to issue the load extended address
> command, before the first page is programmed.

Before the very first access, you have to make sure the programmer is
configured for the same address range as the programming software
assumes it to be.  There is no explicit "good bye" command in the
STK500, so without issuing that load extended address command before
starting to program the very first block, it would be possible the
programmer is still (mis-)configured for a different page from a
previous programming session.

> So, can a load extended address command be issued on all page
> accesses on devices which support that command (and have a memory >
> 128kiB)?

I think it is (probably even on smaller devices), it's just
terribly inefficient.
-- 
cheers, J"org               .-.-.   --... ...--   -.. .  DL8DTL

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