Sun May 29 19:39:03 CEST 2011
AT91SAM7 back channel
Are the DBGU ports/registers accessible through JTAG in monitor mode?
Data sheet SAM7S 12.6.1
* Find out what monitor mode does (as opposed to HALT mode) 
* What are COMMTX and COMMRX signals.
I'm browsing  looking for monitor mode at 5.9 and I find debug
communication channel (DCC) at 5.8. Maybe that's what I'm looking
Googling for '"coprocessor 14" openocd' I get . On the ARM side
it's just a MCR / MRC instruction. On the host side it's scan chain
Is this the same DCC as in "dcc downloads" ? Indeed. This mechanism
is already used; I've found some ARM code so it looks like it places
some code in RAM to handle the other side. Cool.
It has some setup code in arm7_9_common.c and the bulk in
So this _should_ definitely be workable. How to go about it then?