PPM Generator for T9X

[xenon]

Hi everybody.

I searched the forum to find out a similar subject but I didn't found anything

So here's my project: I want to control my Quadcopter or my planes with my computer.

It's "easy" to generate the PPM signal and send it to the T9X with a simple audio Jack. I already have the source code to generate a PPM signal.
But my problem is that my T9X doesn't "use" my PPM signal.

Here's the way I try:
I connect the audio jack on the INPUT of my computer's audio card and record the PPM signal (and I move the sticks). When I check this PPM recording, I can hear the variations of the PPM signal. I also analyzed the signal with Zelscope (an audio card based oscilloscope) and I get this:


So I guess that my signal is correctly recorded.

Then I connect the T9X to the OUTPUT of my audio card and play the PPM. I also activate the trainer options in the menu but nothing happens to my servo...

I even tried the resistor mod successfully on my T9X but still no movement on my servo while I play the PPM recording...

Any idea?

(I hope my question(ssss) are clear )

Best regards.

[MikeB]

It may be the amplitude audio output signal is not big enough. The signal you show on the screen dump is only 0.5V.

Did you turn the trainer enable on in the model as well as enable the trainer inputs in the trainer menu?

When playing the PPM signal into the 9x, the pulse width values should be displayed at the bottom of the trainer menu.

Mike.

[Helle]

Hy,

the signal at the skope you have recorded is a negativ PPM signal
-->gernerate a positiv Signal at th9x Screen 2/12 PPM Frame, 22,5ms, 300us + for Positv

the signal at the skope you have recorded is a AC coupling signal, you can see at positiv an negativ Parts, thats not ok for your purpose!
-->you need a DC coupling signal, ot in other words Signal from 0V to 5V
-->Generete a 0V to 5V Signal, or add +1V and amplify it with 2 to 3 so you get a standrad PPM signal 0V to 5V

The input for PPM at the TH9x jacket must reach 0V to min 3V better 5V and positiv PPM Signal with DC coupling
Thats all!

Lots of others had same Problems.
There are in other fouren some adapters with one or two transistors to generate the right PPM pulses

Same Signal-Problem are with Graupner DSC output jacket for teacher input at TH9x

if you can try use a Summery Signal at a receiver becouse that is DC coupling and 0V to 3V or 5V PPM

There are testgeneratros for PPM signals with a simple atmega8 for 4 to 12 channels in other forum

Helle

[Kilrah]

the signal at the skope you have recorded is a AC coupling signal, you can see at positiv an negativ Parts, thats not ok for your purpose!
-->you need a DC coupling signal, ot in other words Signal from 0V to 5V
-->Generete a 0V to 5V Signal, or add +1V and amplify it with 2 to 3 so you get a standrad PPM signal 0V to 5V

The problem is that sound card inputs and outputs are AC-coupled, so you can't measure nor output a DC-coupled signal with such a sound card scope solution.

[Helle]

Hy kilrah, Mike B,

thats correct and so you need levelshifter with one Transistor to get a correct signal to DSC input at each TX

Look at this Pages, ists from me.
http://fpv-community.de/showthread.php? ... geht-nicht

PC-Software for PPM-Generator --> Sound card output AC-coupling --> Levelshifter --> DSC input at Th9x --> Teacher Screen

Helle

[Romolo]

Are we sure that generating PPM on a PC using the sound card is a safe idea for piloting something ???

[tornback]

Suggestion if the audio signal is AC:
Connect a diode to clip the negative signals (or positive signals) then adjust the volume to hit the exact voltage required.
Tell me if it works.
I will try to replicate what you have done with my Futaba 9C.

[jhsa]

Any updates on this project??

João