Re: ICD BDM, gdb, and error 613 on 68331

["Aaron J. Grier" <aaron at frye dot com>]

On Fri, Nov 12, 1999 at 05:46:29PM -0600, James Ruckman wrote:

> 1. I found an interesting Engineering Bulletin at Motorola which
> describes the error messages which Aaron reported. Maybe it will be of
> some use to the others as well.
> 
> "Startup Problems When Using a Software Background Mode Debugger and
> Booting from RAM or an Empty ROM Socket." Download the PDF at:
> http://mot-sps.com/mcu/documentation/pdf/eb305.pdf

This is _exactly_ the problem I'm seeing.  However, before you can even
change the stack pointer, you need to force the cpu to abort its bus
cycle by pulling down the BERR line momentarily, which the present linux
bdm drivers don't do.

> 2. I don't think the 68332 uses the same memory mapped register set as
> the 68331.  According to the 68332 user's manual, you shouldn't write
> nor read the register at 0xFFFA00. (I think I read this correctly...)

I'm using a 68331...  (I thought the 68332 was functionally equivalent
to the 68331, with the addition of some internal NVRAM.)

> 3. A rhetorical question: why would you write 0x62ff to SIMCR of the
> 68331? Seems 0x60CF is more appropriate (clear SHEN[1:0] to disable
> both external cycles and external arbitration at the beginning of a
> BDM debug session.

You may be right.  I was thinking for some reason that if external bus
cycles were enabled that tracing assembly code would be more accurate.
But like I said before, setting up the SIM _the exact same way_ under
the DOS ICD32 program works fine.

-- 
  Aaron J. Grier   |   Frye Electronics, Tigard, OR   |   aaron@frye.com
  "The simplistic anthropomorphism which asserts that source code has a
   life separate from its creator or maintainer is the product of one
   too many viewings of Tron."  -- paraphrasing of anonymous post on /.

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