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Re: "Free" emulator?


On Mon, Jan 24, 2000 at 12:34:31PM -0500, Quality Quorum wrote:

> I am sick an tired of various BDMs to the extent that I am going to
> put together BDM interface implemented by FPGA/CPLD which will work
> over standard EPP port, and I am going to make verilog/vhdl code for
> the thing available along with gdb target code supporting it.

Don't reinvent the wheel...  There's already a plethora of BDM
interfaces out there including, but not limited to

- motorola two-chip PD interface
- public five chip interface
- P&E ICD interface
- Pavel Pisa's(?) P&E clone(?) (16v8 PAL based)
- various other commercial solutions from EST, softaid, and god knows
  who else...

and this is just CPU32...  I have no idea if any of these work with
Coldfire or PowerPC.

the two-chip is unsuitable due to timing issues.
the five-chip is unsuitable if you want control over the BERR\ line.  [1]
the P&E/Pavel Pisa ICD interface lacks a clean driver. [2]

Ideally support for all of these could be put under the same driver
structure and distributed WITH gdb, or at the very least folded under
the same set of patches.  [3]

[1] I was in the process of modifying my five chip to allow direct
    banging of BERR\, when a working BDM interface box from EST showed
    up on my desk.  Pricy thing, but it works without me having to
    fiddle with it.  I've been trying to get a working CPU32 BDM
    interface under linux now for about two and a half months.  I'm
    certainly no hardware expert or programming wizard, but it seems
    like in the time the 683xx line of CPUs have been out, a
    free-software/hardware geek ought to have put something together
    that works.  I guess there's far less people designing embedded
    systems in their living rooms than are hacking on free software...
    ;)

[2] of the two linux BDM drivers sets I've seen, the Chris Johns / Eric
    Norum driver appears to be the cleanest.  I'd suggest using it as
    the base from which to hack on...

-- 
  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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