On Tue, 21 Jun 2005, Steve Wiseman wrote:

Since the meeting last Thursday I've had a look at Jflash-balloon, and
I think I've now got my head around what it does and how the JTAG
boundary-scan chain works. I've made a start on tidying and reorganising
the code. The (very incomplete) results so far, if anybody wants to
look, are in:

  http://www-civ.eng.cam.ac.uk/brg/balloon/

Basically I've split the SA1110 code from Jflash.cpp into separate files,
and then added some extra files to 'support' the PXA270. As is, the
program should behave much the same as the old code. I haven't yet added
a command-line option to get at the PXA stuff.

Note that I don't actually have a JTAGing cable so I can't even test that
I haven't broken any SA1110 stuff by moving it about.

> Look what I found lurking in the datasheet (design guide)...
>
> 26.4.4.4 Flash Data Register
> The flash data register is a subset of the boundary-scan register. This
> subset of cells pertinent to flash programming facilitates shorter
> programming times using JTAG.

Well if this saves us having to shift all 504 boundary-scan cells on every
write then that would be good... Presumably we'd still need the full
504-cell chain to get at and program the debug control/status registers
and the use the shorter chain to actually write to flash?

I'll have a look at Chapter 26 and see if I can understand it...

Please let me know if anything I've done so far is completely stupid.
This stuff is all rather new to me.



Paul Fidler
-- 
Cambridge University Engineering Department | Tel: +44 1223 332816
Trumpington Street, Cambridge, CB2 1PZ, UK  | Fax: +44 1223 332662