9XR Trainer port problems

[KirkaFordisRex]

Hello everybody. I'm having problems getting my 9XR to receive inputs from the trainer port.

I just purchased my 9XR about a month ago. I haven't modded it in any way. I have the EZUHF JR module installed in the module bay.

In RADIO SETUP page 1/5 Enable PPMSIM is ON
In SETUP page 2/11 I have "Trainer" ON
in TRAINER page 2/5 I have:
RUD := 100 ch4 TRN
THR += 100 ch3 TRN
ELE := 100 ch2 TRN
AIL := 100 ch1 TRN
Multipler 1.0
Cal 0.0 0.0 0.0 0.0


I can move all the control surfaces of the aircraft. When I press and hold the TRN button I can only manipulate the THR (to make sure it's working)


If I plug in an empty Futaba cord (or 3.5mm JR cord) the Cal numbers freeze and will not change regardless of stick position on the 9XR and regardless of TRN switch manipulation.

I have a device called a PCTx which converts PC Joystick movements to PPM via a USB to Futaba cord.
I also have Realflight 6.5 with the interlink controlled with a Futaba plug on the back.

I can activate the PCTx and plug it into the Realflight controller, and control the model airplanes. [This tells me PCTx is operating normally, and sending PPM signals]
I can plug my 9XR into the Realflight controller and control the model airplanes [This tells me that the 9XR is sending PPM correctly]

But if I plug my PCTx into my 9XR, the 9XR does not appear to be receiving any PPM signal. The Cal numbers at the bottom of TRAINER page 2/5 don't show inputs. Without a cord attached, when I hold down the TRN switch, then nubers fluctuate quickly, and by increasing the multiplier they fluctuate at higher intervals. But none of them appear to be receiving a signal. I've scoured these forums and others and tried several of the "fixes":

I have tried:
- Bridging the connection between PPM out and PPM IN on the futaba port. (all this did was freeze the cal numbers permanently until the bridge was removed. (note: I tried all the fixes below with and without the bridge)
-Used the JR port instead of the Futaba. (I opened the PCTx and sent the PPM signal to the PPM IN part of the JR port, and the GND to the GND of the JR port.
-Tried setting the PPMSIM to [OFF]
-Tried removing the UHF module that is attached to the radio.
-Checked the protocol of the radio [PPM 8CH 300us]
-Tried unplugging the Battery, then plugging in the PCTx and then plugging in the battery
-Reset the Hi-Resolution PCTx firmware to Standard Res
-Checked the MIXER page to see if my PPM was appearing there. (Best I could tell it wasn't but I don't really know what I'm looking for)


I have yet to try:
-Kilrah's circuit that increases the voltage of the PPM from 3v peak to peak to 5v peak to peak.
-A different firmware for the 9XR
-Wiring the PCTx directly to the JR module.
-Measure the PPM from the PCTx on an Ocilliscope. (I don't own one) I can read voltage though with a multimeter.

Any light you guys can shed here? From what I've experienced, this is the single most knowledgeable forum on the internet when it comes to the Turnigy 9XR any help would be appreciated.

-Kirk

[KirkaFordisRex]

Is there any way to test that the trainer port is operating properly?

[MikeB]

Remove the module from the module bay.
Switch the Tx on.
Set the protocol to PPM.
Go to the TRAINER menu.
Plug the trainer lead in to the JR 3.5mm socket.
Now carefully hold the tip of the other end of the trainer cable to pin 1 (top pin) of the module connector. It is worth covering the other 4 pins with something insulating while you do this to help protect from accidental shorts.
Now, the 4 main controls should cause the CAL values at the bottom of the TRAINER menu to change. If they do, then the trainer input is working correctly.

Mike.

[KirkaFordisRex]

I followed your steps and the CAL numbers move (once calibrated) normally without the TRN switch held down. If I hold the TRN switch down, the CAL numbers don't change. Is that normal?

If I reattach the module, the CAL numbers move normally again without a trainer cord. I don't understand what's going on here.


I scrounged up a JR F400 analog 4channel radio. I removed the 72MHz crystal out of the back and tried to use it as a slave to the 9XR. I still can't get the CAL numbers to move with the TRN Switch up or down. I tried with the F400 on and off.

I can make the 9XR slave, remove the module, and send PPM to the F400 and that seems to work, just not the other way.

Suggestions?

[KirkaFordisRex]

I did some more testing today after making my own JR trainer cord and soldering it to the PCTx.

I can now send PPM info to the JR F400 from the PCTX and it's 100% functional. Control surfaces function appropriately.

If I take that cord and plug it into the 9XR there is no response from the 9XR. The CAL numbers freeze and don't change, nor do they pass along the signal to the RF module (with or without the TRN switch pressed). I'm now 100% certain that the problem is with the Turnigy 9XR. It's either defective with the hardware or software, unless someone can see where I have made a mistake setting it up to act as a trainer.

[MikeB]

The fact that the CAL values on the TRAINER screen move normally with the loopback I described (from pin 1 of the module port) indicates both the hardware and frimware are working. When you hold the TRN switch in this mode, you actually stop the output on pin1 because it is actually the input on the trainer connection.

If the CAL values don't change when you use the input from the PCTx, then there is almost certainly a voltage level problem. The input to the 9X has a (processor internal) pull up resistor to 5V (between 20K and 100K), and expects the input to be pulled down to below 1V to be seen as a logic 0.
Specifically, a logic 0 is below 1V and a logic 1 is above 3V.

I've just done a search, but cannot find any info. regarding the voltage levels on the PCTx output.

Do you have any way of looking at the PCTx output voltages (oscilloscope for example)?

Mike.

[KirkaFordisRex]

No, I don't have an oscilloscope, but I have a multimeter and a "can-do" attitude.

[MikeB]

I'm not sure how much we can determine using just a multimeter, but we can try some things.
Using my multimeter in AC voltage mode I measured the signal on pin 1 (top pin) of the module connector (ground is on pin 4). Be very careful doing this as pin 3 is the battery voltage. Best to insulate pin 3 somehow, perhaps plug a servo connector in to it so just one of the servo 'socket' pins is connected.
Doing this, I got a voltage of around 1.1 volts AC. You could try this, then also try the same measurement on the PCTx output.

Mike.

[KirkaFordisRex]

PCTx AC Voltage changes from 0.40 to 0.75 depending on servo position.

[MikeB]

That is probably too low and you need to increase the output level, or buffer it.
I've attached a circuit for the 9X, as drawn by GRUVIN (thanks), that includes a suitable buffer circuit (blue box at the bottom). You could try this, it will still work if built outside the 9X, no need to actually modify the 9X itself. If you do modify the 9X, you will disable the ability to use the PPMSIM option.
This circuit does not need any power to operate, it just accepts a low level signal and 'boosts' it to the full 5V level due to the internal pull up resistor to 5V in the processor.

Mike.

[KirkaFordisRex]

I've built the circuit and attached it in-line between the PCTx and the JR cord. I'm getting 0.00 voltage from it. I've got a good ppm voltage to the "buffer" board (0.46v) but nothing after it. It's possible my circuit is screwed up, how would I test my circuit to see where the problem is? This is my first circuit.

[MikeB]

The circuit is "open collector". This means it only drives to 0V and relies on the pullup resistor in the processor (when connected) to get a positive voltage. If you haven't got it connected to the Tx then it will stay at 0V.
If you can, plug a trainer cord into the Tx, with the Tx on, and check you get around 5V on the other end of the trainer cord.

Mike.

[KirkaFordisRex]

So I went ahead and plugged the JR trainer cord with the boosted signal into the 9XR's trainer port and got nothing. The 9xr still failed to detect the signal. While the 9XR was powered on and had the trainer cord plugged in and the PCTx was sending a signal, I measured the AC voltage of the PPM and GND wires soldered to the booster circuit. the voltage was 0.28 volts. I checked the voltage coming out of the PCTx without the booster and it was 0.46 volts AC.

I checked my handy work with the multimeter. From the PPM input to the Collector leg of the transistor I had 330 ohms. From the Base leg to the Emitter leg I had 150,000 ohms, and from the Base leg to the PPM out I had 4,700 ohms. It seems like the soldering and circuit building is right. Unless, I'm sending PPM the wrong way. I'm presuming it comes from the "PPM IN" and comes out after the 4K7 resistor, and is then sent along the JR cable into the trainer port.

I have tried switching the PPM wires and the 9XR didn't detect it that way either. What do you think is the problem?

[KirkaFordisRex]

I reviewed another hack from the PCTx site found HERE and they had the PPM from the PCTx on the Base leg of the transistor, while the PPM signal going to the buddy port was on the Collector leg. I tried their circuit (and it didn't work either) and then I tried the Gruvin hack with the PPM from the PCTx on the base leg.

The 9XR is still non-responsive but when I checked the AC voltage on the cord with it plugged into an [ON] 9XR the voltage was 0.63 to 0.80 and kept fluctuating between that high and low.

Additionally none of these boosters work with sending PPM to my JR radio.

[MikeB]

This should work. Please check your PPMSIM settings. If you have PPMSIM enabled (RADIO SETUP) AND PPMSIM set as the protocol on the selected model, the 9X will actually be using the trainer input to send a PPM signal out. Make sure at least one of these is OFF.

The hack you refer to is the correct connections, PCTx to the base, collector to the radio.
You could try using different resistor values where you have 150K. Try 47K and 4K7.

Mike.

[KirkaFordisRex]

the 9X will actually be using the trainer input to send a PPM signal out.

Just to clarify: are you saying the 9XR will take the PPM signal from the trainer port and sent it to the module bay pin?

I think that's what you're saying, but I just want to be sure.

[MikeB]

Have a look at the diagram on this post: viewtopic.php?f=5&t=2&p=7541&hilit=ppmsim#p7541.

Mike.

[KirkaFordisRex]

According to that diagram I'm trying to get "Existing Master".

Take PPM from the Jack Socket, and sent it to the TX Module, that's what I want to do.

[MikeB]

Yes. As you can see from the last 2 diagrams, if PPMSIM is enabled, and selected in the model as the protocol, then the trainer jack is used as an output.
I was surprised you have a fluctuating AC voltage measurement, and thought it might be because the radio was sending out a signal as well as the buffer sending one in. Since these would be out of phase, I thought that might cause the variable AC voltage measurement, so thought I would check.

Mike.

[KirkaFordisRex]

Well i tried both PPSIM ON and OFF just to be sure. Neither worked. Here's my SETUP pages:

SETUP 2/11
Name Airplane
Timer 10:00
Trigger OFF
TriggerB ---
Timer Count Up
T-Trim ON
T-Expo ON
Trim Inc Medium
Trim Sw ---
Beep Cnt RETA123
Proto PPM 8CH 300uSec
PPM FrLen 21.5mSec
Shift Sel POS
E. Limits ON
Trainer ON
T2ThTrig OFF

--------------------------------------

RADIO SETUP 1/5
Owner Name Kirk
Beeper xShort
Sound Mode Beeper
Contrast 23
Battery Warning 9.0v
Inactivity alarm 10m
Filter ADC SING
Throttle Reverse OFF
Minute beep OFF
Beep Countdown OFF
Flash on beep ON
Light Switch AIL
Light off after 60s
Light on Stk Mv OFF
Splash Screen OFF
Splash Name ON
Throttle Warning ON
Switch Warning ON
Default Sw TRE012AG
Memory Warning ON
Alarm Warning ON
Pot Scroll ON
BandGap ON
Enable PPMSIM OFF
Mode 2

[MikeB]

Are you using the original firmware that was installed on the 9XR?
Have you tried diffferent resistor values for the 150K resistor?
If you are prepared to flash new firmware, I could build a test version that displays some information about what is being received, if anything, on the trainer pin of the processor.

Mike.

[KirkaFordisRex]

Yes I'm using the original firmware. I don't have the USB adapter to flash new firmware.

I tried 2 4K7s in a series in place of the 150K still nothing. I took apart the entire circuit and rebuilt it, and found that I had wired the circuit incorrectly the first time, I had transposed the pins on the transistor. I rebuilt it correctly, and retested everything from then forward, still nothing. Although now with the JR plug inserted in the trainer port, when I flip the trainer switch I can hear the throttle go to 50%. I can still not get any PPM into the radio, and my AC voltage on the trainer cord has never reached 5v.

[KirkaFordisRex]

Well I've fixed the problem, more or less.

I did some bench testing and discovered that the JR module would accept a PPM signal from the PCTx with no problem.

My challenge then was to force the transmitter to send the PPM from the trainer port to the module, while overriding the PPM from the transmitter brain.

I accomplished this by locating the wire that sends the PPM signal from the control board of the 9XR and disconnecting it from the plug.

I then soldered a wire to the mount of the aforementioned plug and wired it to a SPDT switch that I installed at the top of the transmitter. I wired that switch to the backside of pin 1 (PPM pin) that sends it to the module.

I located the signal pin of the 3.5mm trainer port, and soldered a wire from that, to the above reference switch.

The result was a switch that would select which PPM signal would be sent to the module. Direction "A" would select the 9XR board and the transmitter would function normally. Direction "B" and the transmitter would send PPM from the trainer port to the module.

-Kirk