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I do the same for testing dip switches, like on Atari pinball MPUs, turn
all of them on, read FF, turn all off, read 00. <br><br>
<i>Warning - Random blather below:<br>
</i>I am looking at automating the reading of switch matrixes by a
simple jumper plug with some diodes. Have the Strobes all going to a
separate Return, or , better yet, matrix all the possibilities with
a wiring blob (diodes and wire), and then treat the switch matrix as if
it was a RAM location in memory. Write AA and then 55 and see if any
errors appear. Perhaps a simple ROM chip might help out here, use the
strobes as the Address, and the Returns as the DATA. Run a Signature on
the "address"? But how to specify the failing Strobe/Return
line? Use the Walking bits test? Just some random ideas I'm
afraid...<br><br>
Looking in the Troubleshooter newsletter for an article on checking
cables using a pod, for the switch matrix you already have all the
select logic you are simply figuring out the test algorithm. Must re-read
that more carefully.<br><br>
John :-#)#<br><br>
At 10:35 AM 19/06/2002 +0100, Andy Welburn wrote:<br><br>
<br><br>
<blockquote type=cite class=cite cite>> Well how do you do
it?<br><br>
i thought i'd answer on-list :)<br><br>
hit READ, select the ADDR OPTION to I/O then read address 1<br><br>
repeat for addresses 2 and 3 for the other input ports..<br><br>
I didn't check them out fully, however, address 1 is for player 1
controls<br>
and coin/start for sure. Port 2 has the tilt switch.<br><br>
I didn't bother with the rest as the main things i was looking for
were<br>
stuck switches, of which there are none on this troublesome pcb
:(<br><br>
the read result has to broken into its 8 bits, if you read the address,
then<br>
hold the appropriate button and re-read, the result will change... its
pure<br>
sorcery i tells ya!!<br><br>
> Thanks,<br>
> Kev<br><br>
Andy</blockquote></html>
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Received on Thu Jun 20 22:25:48 2002
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