RE: IEEE Adapter

From: Baltissen, GJPAA (Ruud) <ruud.baltissen_at_apg.nl>
Date: Thu, 1 Mar 2012 08:29:18 +0100
Message-ID: <219DEB1536CDE04E98DDD8620CA8CD68275BB1@winsv293.office01.internalcorp.net>
Hallo Jim,
 


> But, since they are mapped to the same pin on the IEEE connector,
> even a 1 to 1 mapping seems like it would fail.

In a schematic both connectors look the same. But in the real world the
pinout of both the IEEE connectors are mirrors of each others. For
example, have a look at the numbers of the LPT port: #1 is top-right.
But #1 at its counterpart is at top left. And this is exactly the same
for the edge and the connector soldered to the edge.

But why did I use the LPT port as example? Eagle couldn't provide me
with the male part of the IEEE connector. In fact I have never seen one
on a print; all devices use the female part. So does it exist at all? 

 
> IEEE-488 is not my forte, 

But it is mine, I dare to say :)


> I probably could fit an RTC footprint on some pins there in a way
> that would not interfere with normal operation... 
> EEPROM would also work, if the above works. 

The moment the system is in rest, everythin UNTALKed, UNLISTENed and ATN
= (H), you can do everything what you like to do with the IEEE lines
except ATN. So you could add a serial EEPROM, RTC or whatever and handle
it. 
But the moment the system takes over the bus again, I cannot guarantee
anything. AFAIK all combinations of control signals are possible. So it
is you that has to provide a mechanism that prevents the bus to address
the device(s) by accident.

If you want to add some ICs anyway, why not adding a microcontroller
that handles the IEEE bus? Once having this controller, you can add
other features, like uIEEE/SD :), the sky is the limit. But I haven't
any idea where you want to draw the line.


> Is there a project out that adds joysticks or IEC routines to the IEEE
pins?  

Never heard of one. It is doable, the most simple idea would be using
the 8 data lines plus two of the control lines for two joysticks with
each 5 signals. But... it means you're not allowed to touch any joystick
the moment the bus is needed by the system. And I don't think that that
is very user friendly. 
Putting the joysticks behind the microcontroller I mentioned above,
won't be programmer friendly and very slow IMHO. 

My opinion: if you want joysticks, connect them to the keyboard.


> blinkelights on the signal lines, to allow it to be used for
> debugging IEEE issues?

Great idea, I soldered one myself as a help to debug CBM-HD :)


--
     ___
    / __|__
   / /  |_/     Groetjes, Ruud
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    \___|       URL: Ruud.C64.org


 





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Received on 2012-03-01 08:00:31

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