Re: Electronics Question

["David Buckley" <db@xxxxxxx>]

RS232 specs define one of the states as betweeen 3v and 25v, and the other
state as between -3v and -25v.  However, most RS32 receivers use something
like a MC1489 for reception, which kindly interprets greater than about
1.5V
as on, and less than 0.5V to 1V as off.

So in principle, over short-ish wires (and at 1200 baud, short-ish need not
be very short),  if your output voltages are compatible with thiose above,
you can connect your device direct to a normal RS232 port, and it will
probably work.

Gotcha: RS232 drivers and receivers all invert, so your output signal from
your box may need inverting.  If this is thecase, a RS232 driver (the
MAX232
will do fine) is the simplest option, unless its a PIC or something with
bitbanging serial and you have the source code, in which case just swap the
bit polarity round.

----- Original Message -----
From: "Stuart Poulton" <swp@xxxxxxx>
Newsgroups: tex.com.ml.ukha_d
Sent: 23 February 2002 19:24
Subject: [ukha_d] Electronics Question


> Hi,
>
> I'd like to take a data signal clocked at 1200 Baud, from a battery
> powered deivce (power is 3x1.5V AAA) for connection to a serial input
at
> either 5V or RS232 levels, any suggestions on the best way to do this.
>
> Note I only need to read the data.
>
> Cheers
>
> Stuart
>
>
>
>
>
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