Re: catbox usage

Kevin,

The signals you are trying to test D(7:0) come from the catbox/fluke itself,
so looking at them doesn't tell you much about your board. Another words,
you're looking at the output of the CB and could make the same measurement
with the board disconnected.

On the fluke, these signals will only be valid for one cycle, so you
couldn't probe them manually in the manner you are describing (the level
you're looking for would be long gone by the time you put your probe was on
the net).

If you have a fluke and a CB, which it sounds like you do, use the fluke. If
you have a fluke, the only reason to use the CB is for signature analysis.

Moving to a higher level, what is the purpose (for you) in doing this test?
There is no ram at that address (0x0), so you won't be able to read back
anything you write. If you're trying to run a ram test, you might try a
higher address (e.g. >= 0x4).

Also, this is a raster game and you are posting to the vectorlist.

-Mark

On Wed, Nov 25, 2009 at 3:56 PM, Kevin Moore <talon.k@gmail.com> wrote:

> So I'm still new at this and I'm hoping that someone can help me understand
> what is going on.
>
> I'm trying to troubleshoot a liberator board, and I've run into a snag.
>
> I've thus far been able to run diags with a catbox to check the address
> lines. Those check fine.
>
> So I moved on to the Data lines and that's where I'm having problems. Both
> in using the catbox, and the fluke.
>
> Seems simple enough, remove the cpu, plug the 50 pin edge connector, tie %0
> and %2 together, and ground the watchdog dis.
> Tester self test = off
> tester mode = r/w
> bytes=1
> pulse mode = unlatched
> r/w mode = off
> r/w = read
>
> When I write AA to address 0000 I'm supposed to check the inputs on E2
> which is a ls245 so I check the input lines first according to manual.
>
> I'm supposed to get the following pin 11 high, 12 low, 13 high, 14 low, 15
> high, 16 low, 17 high, 18 low. What I have is 11 high, 12 high, 13 low, 14
> high, 15 high, 16 high, 17 low, 18 low.
>
> Now when I write 55 to address 0000 I get the same thing.
> The other thing that happens is that the outputs are not reading high, or
> low.
>
> Now if I replace the CPU, and let it run, the outputs toggle as well as the
> input. So I'm not sure what's going on..
>
> Here's the schematic of E2 and the cpu.
>
> http://lh5.ggpht.com/_s5vOp-dzA9Y/Sw2kSWICiwI/AAAAAAAADlA/sSf1UtjxmsA/s512/cpu.jpg
>
> So I'm not sure what's going on.
>
> Thanks,
> Kevin
>

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Received on Fri Nov 27 13:27:30 2009