rtems gdb/insight to jtag

-boggy boggy at elab.tmf.bg.ac.yu
Tue Aug 31 22:13:34 UTC 2004

>> 2. debug-cable and gdb with bdm4gdb patch for
>> Motorola's MPC860 (http://www.vas-gmbh.de/software/mpcbdm/ < patch and 
>> cable schematic is included in tar.gz)
>> This cables cost about 50EUR, but that interfaces
>> are very simple (about two HC chips + possibly some diodes and
>> transistors... we built all of this in our labs... nothing special
>> we have one cable per software or hardware engineer, and this is good...)
> 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?

MPCBDM don't use jtag port, but BDM (Background Debug Mode/Monitor)
interface (this is some of Motorola debug interface implementation
similar to older MC68360 BDM)

> 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).

We don't use any of "wiglers" or "ravens", only free-schematic version.

> How do you go about programming flash on your target with mpcdbm/gdb?
>> 3. Now, we use BDI2000 with firmwares for MPC860 and MPC8260.
>> All of this tools works well...
>> Cheap cables are slow for upload large images and debugging, but it 
>> works...
>> We buy BDI2000 because we don't have any freely available cables for 
>> MPC 8260, but this "cable" is very fast... and, because this, we also 
>> buy a firmware for MPC860...  but we have single BDI2000 hardware, and 
>> this is
>> enough...
> Do you connect to your BDI2000 with ethernet?


  I can see why you just
> bought one since they are expensive (see my other message).

Yes, it is expensive, but if you need fast and good hardware debugger 
for gdb this is good choice. If you need debugger for processor
with JTAG debugger interface documentation covered with an
NDA, BDI2000 is a good choice... also. (BDM interface is documented in 
processor manual for MC68360 and MPC860 without any sort of NDA!)

This is another reason why we don't have "free hardware" debugger
for our MPC8260, and/or your PPC4xx, and we must byu some expensive 
tool, if wee need to buy food later... or start to build our own 
hardware debuggers (closed under NDA)... :)

>> We have success with it in both operating systems we use in our 
>> boards... RTEMS and Linux (for Linux especially, listed cheap debugger 
>> cables is better than more other "cheap" debuggers available in the 
>> market)... and gdb is probably more than 60% "secret" of this success....
> So you mean cheap bdm4gdb adapter and cable works better on embedded 
> linux than BDI2000?

Of course not, but our cheap debuggers is very usable...

  What other "cheap" debuggers have you used, Macraigor?

We don't use any, but we read mailing lists, and hear for some
problems... in our history, we have trouble with Leuterbach
BDM debugger for MC68360 (this one have problems with timings
when processor run at 32MHz and not only 25MHz... )

With "Open Hardware" cheap debugger cable (they have same problem) we 
solved that problem with some delay to one signal... and this works for 
a years...

>> We also build some good software routines for production testing...
>> and BDM cable is our only one tool for this...
>> With good hardware debugging interface (BDM or JTAG), gdb is great 
>> tool, not only for software debugging but also for hardware debugging, 
>> for
>> any new and prototype board... at end, I'm hardware engineer only :).
> Thanks for the info, boggy!

No problem...

Best regards,


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