gnupic: Re: [gnupic] Line recievers
Subject:
Re: [gnupic] Line recievers
From:
Arnim Littek ####@####.####
Date:
25 Oct 2006 08:43:13 +0100
Message-Id: <200610252031.48292.arnim@actrix.gen.nz>
On Wednesday 25 October 2006 18:58, John Woolsey wrote:
> I am trying to build a 24 volt micro switch circuit to a ttl input
> switch on a pic micro controller. I was told to use a line receiver. But
> everything I look at seems to be a high voltage rs-232 that goes
> positive and negative. I just want a +24V line through a switch into a
> line receiver. What chip should I use?
If you want TTL input, then you want high above 2.0V and low below 0.8V on the
micro, is that correct?
You don't say what switch levels you expect to tolerate on the 24V side. How
noisy is your 24V cct? Is the switch debounced?
How fast do you want the reaction? If you're just detecting a level change
with no speed considerations, a resistive split with a small capacitor on the
bottom resistor is fine. If your 24V line is really noisy, prone to spikes,
then you might want to protect your comparator-with-hysteresis.
Lots more information required in order to come up with something like an
optimal solution.
FWIW,
Arnim
