[nSLUG] External temperature sensor (Gerald)
budman85 at eastlink.ca
Tue Dec 11 16:58:32 AST 2007
Dop Ganger wrote:
> On Mon, 10 Dec 2007, Mike Spencer wrote:
>> I've been irritated for years that there was no similar, easy-to-use,
>> analog-to-digital port on a PC. The joystick article seems to suggest
>> that there's a way to do this kind of thing after all without getting
>> onto the GPI Bus.
> It's not quite so simple. There's a bit of fiddling involved; from memory,
> I had to read the port, wait for 10ms (ish?), and then loop reading and
> waiting until the value changed and then the differential of the two
> values was the analogue value being read. Once you've cobbled together a
> routine to do that things are good to go. My only caveat is the Creative
> Soundblaster PCI joystick ports were somewhat uncooperative. As Daniel
> noted a thermistor is non-linear, I think I took around 20 readings to get
> a reasonable level to alert on (this was for a server room to alert on
> If you want to do a similar thing on the digital side the parallel port
> works well. I helped build a two-person roller race setup using a magnet
> and reed switch using two lines off a parallel port which did the trick
> quite nicely for next to no outlay - though it was a pain hacking off the
> end of an old printer cable and tracing each piece of wire because I was
> too cheap to buy a plug and hood...
I remember adding a thermistor to show temps on my BBS when I had the
Commodore 64/128 running.
Back in the good old days (BW-Before Windows), my friend (who was good
at electronics) and
I setup an interface to control stereo equipment to automate mass
recording of DJ CD's (he worked as a DJ).
At first we used the serial port, but that limited us to one channel.
So I explained how we
could use the parallel port interface. He then picked up a few timer
chips from Radio Shack
and bingo. We also interfaced a third parallel controller (some cards
were capable of
the third address) to give us 16 inputs.
The system worked for many years - I think he still uses it from time to
He eventually ported to Visual Basic. I've been trying to get him on
No luck so far.
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