Hacking a TX, turning it into a computer radio
 

Hi:

I need to identify the wire that carries the PPM signal from the main circuitry board to the RF module, inside a HobbyKing TX.

The goal is to turn it into a computer radio. For that purpose I have to add an Arduino microcontroller, an LCD screen and of course the Arduino will have to produce the PPM signals, replacing the original circuitry. Another reason being the TX has 4 channes but the RX has 6, so I can use those extra 2 channels provided I manage to create the PPM signals.

I found 4 wires connecting the main board with the RF board, I guess they are GND, V (5v? 3.3v?) and signal, but the 4th wire leaves me puzzled. To complicate things further, I don't have an oscilloscope.

I'd appreciate any hint or help.

Thanks, Robert.

As noted in reply to your post on RCG, very few modern radios use PPM internally. What you likely found was a serial connection. What did your oscilloscope show you?

Andy

Ok if it is not PPM anymore, what then?

Read my second sentence. The third one is helpful also.

Well it is an old HobbyKing V1. The RX is in fact two RXs wired together.

As I said in my post, no osc here.

The Arduino is capable of serial comm. If that is the case, I should get an osc and see what is present in the line. Of course I should find a friend that owns an osc.

Yes, you should get a scope (that was the point in asking about it even though you said you didn't have one). You're going to need it. Let me be more clear: you are going to NEED it.

There are many types of serial communication. The scope is going to help you determine not just the hardware used, but things such as clocking. Don't be surprised if there isn't a library for what you need.

Have fun!

Andy