RC Mixer for VTail or Flapperons

This mixer uses a 16F84 PIC to mix two channels together,it has the following features :-

Servo reversing on both outputs.

100% or 50% of either input mixed with the other.

The idea to do this came from having built a similar kit for such a mixer supplied by Ken Hewitt which works very well so I decided to write my own code for one just to see if I could do it myself.

A complete kit for a Vtail mixer with the same features is available from Ken Hewitt for those of you who do not have the facility to program your own PIC`s. He also has many other projects available,and can supply a PCB for this project at £2.50 ask for his small PIC project PCB, I have used the same layout for convenience.

Source code Mpasm hex Tasm obj PCB overlay New PCB Circuit Diagram

Switch functions SW 1 I/P 1 50% SW 2 I/P 2 50% SW 3 REVERSE O/P 1 SW 4 REVERSE O/P 2

UPDATE

The origional source code polled the inputs on alternate frames while still sending both outputs in each frame, the mixermkll source code polls both inputs for each frame and may make the servo's a bit faster to respond and jitter less but there is very little difference.

Source code

MPASM HEX for the mixer MKII

PCB Layout

Theory

Problem : how can I make the PIC measure the first pulse first when the inputs can be plugged in any way around and also make sure that the output pulses occur in a blank space ?

With a frame length of 20 ms and two input pulses of a maximum of 2 ms each there must always be room for the output pulses somewhere. You can see from the drawing that if the PIC starts on the second pulse that the output pulses will occur during the next second pulse so the PIC will not get around to measuring until the next first pulse comes along and will then generate output pulses in blank space, so no special code is needed to make sure that the PIC measures the puses in the right order because it happens automatically