Date: Sun, 27 Oct 2002 11:19:15 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: David Nicholas Kayal <davek@saturn5.com> Cc: nbari@unixmexico.com, freebsd-hackers@FreeBSD.ORG Subject: Re: i am looking for a 5 volt signal Message-ID: <200210271919.g9RJJFEm091313@apollo.backplane.com> References: <Pine.BSF.4.44.0210270918380.364-100000@blackbox.yayproductions.com>
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:
:Shouldn't the fact that the signal is in a while loop keep the 5 volt
:signal going? Isn't the parallel port being blasted with the
:value 255 over and over again?
:
:The serial port will not fulfill what i am ultimately trying to achive. I
:am trying to have the parallel port to control 8 relays each turing
:on/off based upon which bit i send out to the port.
:
:..
:> try using also the serial port and a logical buffer
:>
:> the 5 volt signal is very fast and your multimeter is maybe not to fast
:>
:> > I'm looking for a 5 volt signal.
Uh guys. Parallel port digital outputs do not generally have a whole
lot of drive. I really doubt a parallel port output could drive a
relay.
And it's probably TTL level equivalents, not CMOS. Even if you ganged
the output bits together I doubt you would get enough drive out of
them.
A serial port output (+/-12 but you may see +/-10 or -5 and +12 or other
out-of-spec combinations) is far more likely to be useful in driving
a relay, though again there will not be much drive. It would be far
better to supply the power you need from another source, like a +5V
power supply. Or just get a wallwart with DC output and run it through
a linear regulator. At least then you aren't likely to burn the house
down :-)
-Matt
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