rtems gdb/insight to jtag

Erwin Rol mailinglists at erwinrol.com
Tue Aug 31 22:00:12 UTC 2004

On Tue, 2004-08-31 at 23:43, Smith, Gene wrote:
> -boggy wrote, On 8/31/2004 3:32 PM:
> > Hello Gene,
> Looking at the "cable" schematic it appears to drive a standard JTAG 
> port as I find on my ppc405gpr (IBM) board. So this should also work 
> with ppc4xx processors too, not just MC6xxx right?

The problem is the spec of the BDM commands, it might electrically be
the same interface, but for example for the MPC82XX you only get the BDM
command+register description under NDA (also useless for open source
projects). The only two MPC it is possible to make OPen Source
interfaces are the 8xx and 5xx. 

> This appears to be a open implementation of the "wiggler" (or possibly 
> "raven") product from Macraigor, right? Curious as to how it differs. I 
> guess it works just as well since Leon P. now say this is what he uses 
> (bdm4gdb==mpcdbm I think).

I believe the open source ones all have the same roots, a few transistor
version by some Russian guy. But they are not exactly the same, for
example the VAS one is a GDB-only path, where i split things up in a
library and a patch. Leon used my version,or tried to use it, since he
helped me find some smaller problems.

> How do you go about programming flash on your target with mpcdbm/gdb?

By uploading code in the shared-onchip memory, and than run that
program, in combination with uploading the data via the BDM port. If the
shared memory is needed for other things (like in a running system) it
will can do the whole thing (slow) via BDM too. The BDI uses JTAG
(wiggling the real pins) i think, so that works for any JTAG supported

The next problem is that LPT ports are starting to disappear :-/ So at
some point the interface will be useless. Maybe i will build one with a
EZ-USB or so, but as long as i don't really need to i won't. 

- Erwin
      Erwin Rol Software Engineering - http://www.erwinrol.com/
tel:+49-(0)8024-479378 gsm:+49-(0)171-6929198 email:info at erwinrol.com

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