gnupic: Re: [gnupic] Line recievers
Subject:
Re: [gnupic] Line recievers
From:
Dan Andersson ####@####.####
Date:
25 Oct 2006 19:00:34 +0100
Message-Id: <200610251900.28339.dan@andersson.co.uk>
Why even use a chip?
Use pin diode(s) instead. They are easy to control and are surprisingly simple
to drive. Most cheap pin diodes give you switch times n the GHz region so I
wouldn't worry about the speed and also, more important, the footprint for a
diode and the corresponding resistor is so small.
//Dan, M0DFI
On Wednesday 25 October 2006 18:42, John Woolsey wrote:
> The application is an input switch within a pinball machine. The reason for
> the high voltage is to ensure that there is not interpherence. Reaction
> time within 100 ms would be acceptable. All of the microswitches are
> depressed for longer periods of time than that.
>
> The leading microcontroller to use is a PIC18F2450. 8 of the pins would be
> configured for input. 1 to a pot for configuration (A/D conversion gives me
> the ability to adjust the input number.) And the remaining (14) for output.
>
> I want to wire a 24v supply to microswitch to a line receiver that outputs
> a TTL output to my microcontroller input. This seems the standard pinball
> way to do input. They question is what chip do I use?
>
> - thanx - JAW
>
>
>
>
> ---------- Original Message ----------------------------------
> From: Arnim Littek ####@####.####
> Reply-To: ####@####.####
> Date: Wed, 25 Oct 2006 20:31:48 +1300
>
> >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
> >
> >---------------------------------------------------------------------
> >To unsubscribe, e-mail: ####@####.####
> >For additional commands, e-mail: ####@####.####
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: ####@####.####
> For additional commands, e-mail: ####@####.####
--
Dan Andersson, M0DFI
####@####.#### ####@####.####
