Futaba, Art-Tech, Transmitter PPM Channel Expander with Arduino

Futaba, Art-Tech, Transmitter PPM Channel Expander... 40 Mhz, 35 MHz, 72 MHz transmitters with Arduino...

I used Arduino...
First I tried to find PPM input and output pins on Futaba Transmitter (T6EXHP)... I tried  backside connector (Buddy Box) for reading...  I opened transmitter's cover... I cut PPM IN and PPM Out signals between "RC card" and Main card... That didnt worked... I cut MOD signal... That worked for "no output"... But I cant transmit Input to Output with Arduino...

After that I opened Art-Tech 4 channel transmitter and traced Audio Output (PPM Output) jack's line to MicroController's pin... Separated that pin as Input and Output... That was TTL so it worked with Arduino...

Next step was writing Arduino Uno Code...
Download...

Next, used Arduino Oscilloscope for looking voltages of Futaba T6EXHP's MOD signal...

Red is PPM Out, Blue is MOD input (reverse)...

MOD signal is reversed and 2.5V high... So I used PPM Out signal for input and MOD signal for Output...
It worked by reversed Input to Output test...

FUTABA T6EXHP Wiring :

FUTABA T6EXHP Wires

First Hardware Test for Futaba (simple input to output redirection)  : download

3 Position Switch :
I used two switch because one 3 pos switch seem to me not safe... You may use one analog switch ( Futaba T6EXHP's 5 and 6.th channels switches are digital (2 positions)...)

3 posisiton switch

Futaba Channel Expander with ATTINY Code Download Here....

Next problem is Attiny's 5 second startup delay... Removing this delay is a bit hard...
To remove 5 seconds delay. Follow this page :
http://www.instructables.com/id/How-to-unlock-Digispark-ATtiny85-and-convert-it-to/
Use: "micronucleus-1.11-entry-jumper-pb0-upgrade.hex" for bootloader...