GDB-BDM erratic phenomenon

Eric Norum eric at
Wed Jun 7 15:42:08 UTC 2000

"Kim, Jeong-Hwan" wrote:
> CPU is MC68360 and gdb patch is gdb_4.18_bdm.
> The wrong operation of my bdm board may result from just my soldering mistake,
> not schematic problem.
> I used RESETS instead of RESETH.
> Does it affect the operation of BDM ?
> Not connecting Vcc to the bdm board, I ran chk program ((ex) chk /dev/bdm0).
> The check program wrote and read the Address registers, Data registers and
> it converted PC to 0.
> I seemed that the check program read and wrote reigsters correctly.
> ( For each register "..........................." was displayed and no error message )
> But I'm not sure it operates normally - because when I connect Vcc to my bdm board
> it returns errors and when I ran executable files with gdb its result was not good.

1) What BDM circuit are you using?
2) See section 9.9 of the MC68360 User's Manual -- You should use
3) I don't understand what you mean by `connect Vcc to the bdm board'. 
The BDM circuit should receive power from the 10-pin cable connecting it
to the target system.  Again, see section 9.9 for details.
4) You must be careful to avoid ground-bounce problems between the PC,
the BDM circuit, and the target.  In particular, the cable between the
BDM board and the target should be no more than 30 or 40 cm and the
cable to the PC should be no more than 1.5 to 2 m.
5) Try different BIOS parallel port settings.  Things usually work best
if you disable all `enhanced' or `extended' features.

Eric Norum                                 eric at
Canadian Light Source                      Phone: (306) 966-6308
University of Saskatchewan                 FAX:   (306) 966-6058
Saskatoon, Canada.

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