If you don't mind an extra chip you could use a logic gate to get three
outputs from your two outputs in the National chips. You know, signal 1,
signal 2 and both. Or better yet, have the PIC detect when both signals are
present.  A lot of three channels remote controls work this way.

Rogerio


At 01:52 AM 18/06/96 +0000, you wrote:
>PIC purists - lease forgive me. This question is only indirectly PIC
>related, but what the heck - LCD displays are discussed all the time!
>
>Here is the question. I have a project based on a PIC 16C61. The
>input is connected to 3 buttons. I want to add RF remote to it. My
>garage door opener seems to have exactly what I want in it - a single
>chip design with a 3 button input. The problem is that I don't
>recognize the chip used in it - it is marked 125C67.
>Does anyone know:
>1. What is this chip and who makes them.
>2. Is there a place I can get ready made transmitter and receiver
>modules?
>
>I'm aware of the National Semi LM1871/LM1872 chips, but the design
>seems more compicated - there are only 2 on/off channels and power
>switch is separate. My remote is activated by a single contact pair
>(one of three).
>
>Thanks.
>
>--
>-Alex.
>
>