"momentary" IR decoding

I am designing a motorized drape controller. I have a PIC 16F84 decoding IR signals to my main controller chip. In response to a button press on my remote, the PIC has to send a signal to my main controller chip that in return sends a PWM signal to an H-Bridge.

My main issue is coding a "momentary" signal from the IR decoding PIC to the main controller. When I press the button, I can either send a serial signal b/w the two or simply connect an i/o port from one to the other, correct? With that background, here is a list of issues:

1) There is a lot of "lag" time when I use a serial connection b/w the decoder & controller. Thus I loose any detailed control of the motor. I have no true "momentary" signal transmission. Do you know a reliable method to use serial signals for a momentary control type? I can’t design a loop statement that effectively detects the same signal being sent and keep a PWM active on an output pin.

2) If I use direct i/o port interfacing, then I have problems with noise in the circuit when the motor starts running. In other words, the TTL signal is not strong enough to be effective over the noise, I think.

Of course I would prefer to use serial commands to tell my main controller which button was pressed. I am at a loss with this now. I need to find a way to have the main controller tell is the button is being pressed and held, all while minimizing lag time and allowing the main PIC to supply a clean PWM signal to my H-bridge. THIS IS DRIVING ME CRAZY!!!

Do I need to use a RS-232 controller chip?
Also, do you know any clever ways to isolate parts of a design circuit, for example to separate motor power and IC power all while using the same wall transformer?

I really appreciate any help with this stuff. Ive put so much work into it so far, it’s a shame to not be able to complete it.

Alan J Jurim
[email protected]