"Mario I. Arguello" wrote:

> Hi Quentin,
> thanks for your fast response, I know it can be done with a pic, just that I
> have never done any circuit design but I understand some electronics.
>
Mario, I was just making a jest, since you asked on the PIC list. :)

> I want CH2 (Servo 2) output to follow CH1 (Sevo 1) in proportion  (MIX) by a
> certain percentage adustable via a pot on the circuit board. Trims at TX are
> centered and can also be used for further adjustmet but I want the % mix pot
> on the MIXing board.

> Also at any point weather it is full down or full up on CH1, I want CH2
> (Servo) to move  full left and full right independently via CH2 (at TX).

OK, How about this:
The signal from the RX to the servo is a pulse 1000 to 2000 microsecs,
repeated every 20 millisecs. If the servo (thus the Ch on the TX) is
centered, then the pulse width is 1500 microsecs. You might know all
this.
So now you make the PIC read the pulse width of both CH from the RX and
the setting of the pot.
Servo1 can be directly connected to CH1 output from the RX, with a Y
piece connector (or on PC board) with the 2nd end to input CH1 signal
into the PIC, thus the PIC does not need to control servo1 (makes it
easier on the programming side).
The first 1000 microsecs of the signal is don't care, so measure only
the value of each channel after 1000 microsecs, so you have a reading of
0 to 1000 microsecs for each channel, then:
The pot is a value 0-100% of CH1 (call it PCH1)
See if CH2 is smaller or bigger than 500 microsecs. If smaller then
subtract (500-CH2) from PCH1. If the result is smaller than 0 (negative)
then make the result 0.
If CH2 is bigger than 500 then add (CH2-500) to PCH1, if the result is
bigger than 1000, then make the result 1000.
If CH2 is 500 microsecs, then the result is PCH1

Add 1000 microsecs to the result and run the servo.
voila! (I think, hehe)

Hope this helps
Quentin