Re: Arm7 or Freescale Coldfire?

Thus Freescale's MPC5xx line of PPC-based microcontrollers
have a BDM interface for debugging, and a JTAG interface for boundary
scanning. I don't know about any other Freescale PPC devices.

None of the newer ones (8xxx, 5xxx etc.) have separate BDM, all
has gone JTAG - which is good enough an interface, my sole issue
with it is the data secrecy. They claim to keep it secret because
it would be a great support effort, which is of course nonsense.
Some people do get enough data to make debugging equipment.

If my memory serves me right, what Freescale call "COP" is what everyone
else calls a watchdog (it stands for "Computer Operating Properly"),

This is correct, I believe they introduced the term with the HC11 back
in
the 80-s. Or perhaps even earlier than the HC11 - anyone remember?

and has nothing to do with debugging.

Well for reasons I do not remember (I am pretty sure I knew once,
but I may be wrong on that :-) they call COP also the JTAG debug
port, which is exactly the interface they keep secret.

Dimiter

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Dimiter Popoff Transgalactic Instruments

http://www.tgi-sci.com
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David Brown wrote:
Didi wrote:
BDM can save you an emulator.

It certainly can, and probably does most of the time.
The PPC products also have an equivalent of the BDM, but
it is accessed through the JTAG port (that is, there are command
registers which you can use via JTAG without activating
the boundary scan facilities), which would be better than
BDM since it uses a standard cable; however, those registers
are kept secret... BDM was publically specified for at least some
parts of the CPU32 line, but apparently for control purposes
nowadays they do not publish the JTAG accessible debug
port features (for the PPC, they call it COP - whatever this was
supposed to mean, I know I knew it once :-).


JTAG debuggers do not, in practice, use standard cables. For some
reason, known only to those making money from selling JTAG debuggers for
sometimes huge sums of money, every different CPU target has its own
incompatible JTAG debugger, often several depending on your choice of
debugging software.

The BDM is a better interface for debugging than JTAG, because it is
specifically made for debugging, and has additional signals that JTAG
does not. Thus Freescale's MPC5xx line of PPC-based microcontrollers
have a BDM interface for debugging, and a JTAG interface for boundary
scanning. I don't know about any other Freescale PPC devices.

The BDM is, as far as I know, fully publicly specified. Sometimes it is
not always easy to understand the details of the information, but
certainly for the ColdFire and the CPU32 BDM interfaces, I have not seen
any indication of information being hidden or kept back. I know jtag
debugging information is restricted for some processors (like the msp430
and the AVR), but I have no idea about jtag debugging of PPC cores.

If my memory serves me right, what Freescale call "COP" is what everyone
else calls a watchdog (it stands for "Computer Operating Properly"), and
has nothing to do with debugging. But I could well be mixing that up
with another manufacturer.

mvh.,

David




Dimiter (also known as "der Didi" .... :-)

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Dimiter Popoff Transgalactic Instruments

http://www.tgi-sci.com
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Oliver Betz wrote:
David Brown <david@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:

[...]

connectivity testing rather than debugging). BDM is similar to JTAG in
many ways, but a bit more efficient since it is designed specifically
for debugging.
the main difference is IMO that BDM allows memory access without CPU
intervention, IOW "non-intrusive".

BDM can save you an emulator.

If your budget stretches to high-end tools, the BDM
interface can be used for real-time debugging.
There should be also "cheap" BDM interfaces.

Oliver
--
Oliver Betz, Muenchen (oliverbetz.de)


.

Relevant Pages

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