Use EzDSP board as emulator?

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Hi:

I have recently begun using an EzDSP board from Spectrum Digital for the
TMS320F2812.  On the board is a FPGA implementing an embedded JTAG
emulation port, which talks to the PC via a parallel printer port.

I am thinking it is possible to use this board as a JTAG emulator for a
TMS320F2812 chip on *any* board, such as one I design myself.  That way,
I could have general purpose JTAG emulation (though perhaps restricted
to the F2812) for the price of an EzDSP board, instead of the minimum of
$1299 that other emulators cost.

What other limitations might this introduce?  There appear to be flash
programming capabilities in the other emulators, but as I understand the
F2812, it needs to program itself via a RAM based routine anyway, and
this can be done (albeit in a slightly awkward manner) through CCS using
a plugin that TI now makes available on the web for free.

Any comments would be appreciated.

Good day!

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Christopher R. Carlen
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Re: Use EzDSP board as emulator?
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To boil this down where I can understand it, are you saying that you
want to connect to the EzDSP with the parallel printer port from your
DSP, then to your own board from the EzDSP board through JTAG?  That
sounds like a strange thing to do.  I suggest an alternative - watch
Ebay for a Spectrum Digital XDS510PP (parallel port version - cheaper
than USB).  I've seen them for $500, but that was a while ago.  You
are going to have a headache trying to make the EzDSP board work as an
emulator.  I think it would not be worth the effort.  It is also a
good thing to stay current with the TI Code Composer development
envirionment.  I had several problems with the earlier versions but
have been running fine for a year or more on CCS v2.2xx.

SDFlash, from Spectrum Digital, is available in a beta version (could
be released already) that will download to the EzDSP through the
serial port using the `2812's built-in boot functions.  The bootloader
is part of the 2812's boot rom.  This method is FREE, but of course it
really, really strangles development because you'll have trouble
seeing inside your code when it runs.

Re: Use EzDSP board as emulator?
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Connect to EzDSP via parallel port from PC.  Then to my own board not
from the JTAG emulator port on the EzDSP, but from the actual
connections to the DSP chip on the EzDSP board.  I hadn't actually
thought of trying to tie the JTAG port of one EzDSP to the JTAG pins of
the DSP on another board.  I suspect this is the obvious attempt that
they would have made impossible.  That's because the JTAG interface to
the DSP is implemented by the on board FPGA, which also adapts the
parallel port interface to the local JTAG.

So I figured I could scrap one EzDSP board for use as a development
board, and instead turn it into a JTAG emulator, by pulling off the DSP
chip, or just breaking the traces to the JTAG pins, and sending them off
to the JTAG pins of the chip on another board.


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Yeah, I have 2.2.x also.  Good idea to look for a cheaper used parallel
port version.

Thanks for the input.


Good day!


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Christopher R. Carlen
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Re: Use EzDSP board as emulator?
Years ago, I did a similar thing with an eval board from Motorola. It
contained a target evaluation system with a 56303 and surrounding
peripherals and a 56002 with a serial port as a JTAG interface. The supplied
debugger talked to the 56002 which in turn controlled the 56303 using JTAG.
The nice thing about this board was that it had the JTAG connection through
jumpers, to enable a real JTAG debugger to be attached to the target 56303.
But I used it the other way around: pulled the JTAG jumpers and made a cable
that could connect my own 56303 system to the 56002 on the eval board. This
gave me full unrestricted JTAG debugging, even with the later purchased
Tasking 56xxx debugger software.

Meindert



Re: Use EzDSP board as emulator?
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Looking the schematics of EzDSP JTAG connector is one way only (from
external emulator to EzDSP, more specificly from external emulator to
FPGA to DSP). So the only way to use EzDSP is to connect directly to
DSP JTAG pins. More sophisticated approach would be if you would
disconnect JTAG connector to FPGA trace(lifting selected FPGA pins?),
and connect DSP JTAG pins to JTAG connector. This way you would still
have EzDSP functionality when DSP was in socket and when you needed
emulator you would simply take DSP out (assuming you have EzDSP 2812
socketed version).
But this is just theory, if you out this into practice let us know

Mitja

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