Re: Re: How do I tell whether the phone's ringing?

["Paul Gordon" <paul_gordon@xxxxxxx>]

The modem should also send the RI (Ring Indicator) pin high when the phone
is rinnging, which is better than using the TX pin and trying to capture
the
"RING RING" ASCII data, as there "may" be other times
when other data might
be sent, causing false ring detection if you are monitoring the TX pin for
a
high signal....

Can't remember for sure (long time since I did any playing with serial
comms), but ISTR that RI is normally on pin 9 or 11....

Paul G.





>From: Ant Skelton <ant@xxxxxxx>
>Reply-To: ukha_d@xxxxxxx
>To: ukha_d@xxxxxxx
>Subject: Re: [ukha_d] Re: How do I tell whether the phone's ringing?
>Date: Wed, 05 Dec 2001 13:52:15 +0000
>
>Mark Harrison wrote:
> >
> > Hmmm... really wanted something that didn't involve a PC :-(
>
>You could use a modem plugged in to the phone line. When the phone
>rings, the modem will send "RING RING" out the serial port.
Not sure
>whether you can interface this to homevision, as I don't have one.
>
>My guess would be you either have an rs232 port (in which case you're
>laughing) or a TTL IO pin or somesuch, which might be tricker. To
>interface to that I guess you'd need to knock up a simple little
circuit
>- not sure if that's your bag or not.
>
>Although thinking about it, I don't thing modems send out anything else
>down the serial port when they're quiescent, so maybe looking for level
>changes on the modem's serial TX line would be sufficient.
>
>YMMV, HTH etc
>
>ant
>--
>                               /\/\
>ant@xxxxxxx                   (`')                  www.ant.org
>                                ()
>                     Megawatt Winged Avenger


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