9X with FrSky and ER9X as Master and DX7 as Slave

[frviana]

HELP

I'm not sure if its possible and I haven't found any thread about it yet.

I want to have my Turnigy 9X with FrSKY and ER9X as Master and a DX7 as slave connected through the trainer cable/port.
I tried but didn't work and after a few attempts and playing with the cable I blew the fuse on the DX7 (its replaced already).

I'm getting into FPV but not confortable yet on landing with the goggles and I want a friend to use my DX7 to land it for me... Can someone help me with the configuration?

What have I tried:
- Set DX7 as Slave
- Connect cable on both radios
- Turn on 9X and leave DX7 power switch off
- Flip the Trainer switch on 9X to switch (doesn't work)

On my 9X ER9X Radio Setup I enabled PPMSIM

And on the model setup its configured
Proto PPM 8CH 300uSec
PPM FrLen 22.5mSec
PPM 1st Chan 1
Trainer ON

HELP!

[MikeB]

You don't mention having configured the trainer menu on radio setup. This is where you set up the trainer switch to operate, and also calibrate the incoming signal from the slave.
PPMSIM relates to using the 9X as a slave.

Mike.

[frviana]

Thank you Mike... I'm trying to understand how it works and have played with it to try to pass the control to the DX7 without any success. I read in some threads saying you would need a mod with 1K resistor but I'm not clear if is needed or not.

I've tried to setup something on the Trainer menu as below just for kicks and see if I could give control to Slave.

TRAINER

THR += 100 ch1 TRN
ELE += 100 ch2 TRN
AIL += 100 ch4 TRN

Again, for now, my goal is first be able to give control and then I fine tune but I have not been able to pass control to slave by flipping TRN switch.

[MikeB]

When you say you can't pass control, do you mean the 9X keeps control, or you just have no control?

When you have the 9x switched on, and the DX7 connected as a slave, go to the TRAINER menu. The four numbers at the bottom of the screen are the four main channels as received over the trainer cable. These should not be 0, and should change when you move the sticks on the slave Tx.

Mike.

[frviana]

9X controls the channels no problem...
I noticed it was all 0 on the TRAINER screen but then when I moved the cable a bit it changed and got some numbers...
When I flip the TRN switch it moves the servos but the Slave doesn't get control
When I move the sticks or switches on the SLAVE (DX7) the numbers don't change on the TRAINER screen of the 9X

I played around with the cable to see if it was a bad cable/connection but nothing... the numbers sometimes changes when I play with the cable but it never changes when I move the switches or sticks on the DX7.

[frviana]

BTW, I see this thread -> http://openrcforums.com/forum/viewtopic.php?f=95&t=2794
that says I should add a couple resistors to the cable... is this a must have? Are the resistors in series? I'm not good reading circuit design.

[Flaps 30]

frviana - There is a transistor (Q1) between those two resistors in Kilrah's circuit. I don't know if that is applicable to the DX7. Hopefully someone will come up to let us know.

[frviana]

Hope someone comes to help... I blew the second fuse on the DX7 when playing with the cable... I'm not sure if my cable is good... I got a mono cable... when fully inserted on the DX7 I tried to read the voltage and get get nothing in either pin... If I play with the cable I get some voltage but the question is what pin is supposed to carry the + and what voltage it should read from the DX7.

[ShowMaster]

The cable is a 1/8 mono to mono cable. You will not read any DC from the dx7. The signal will be the ppm data out and will be AC. You can see it with a scope but not a meter. There is circuitry that detects the dx7 has a trainer cable plugged in and when off will power up and output a 3v ppm signal. Wiggling the plug around in the jack isn't good for the jack or the circuits, but I think your finding that out.
The issue is that the DX7 puts out a 3v peak to peak AC type ppm signal. The 9x wants to see 5 volts peak to peak input ppm. Kilras's circuit is a level shifter that converts 3v ppm to 5 v ppm and gets its power from the circuits it's in. I never tried it but its a good way to go for the radios. A scope will tell you what's going on but the dx7 ppm circuit need that load to output a ppm signal so measure it connected.
Please post more on how you're wiring this up and what you're doing when the fuses blow. Step by step please so there's more to know for more advice.
SM


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[frviana]

I will try to get another cable. The same cable when inserted on the 9X has one pin outputting 5V and on the 9X none of them outputs any voltage. I understand now what you are saying.

The way I got to blow a fuse (a couple times now) was by inserting the plug slowly (1/4, half and fully) while trying to measure the voltage to see if at some point I would get some voltage on the pins. While doing this I read 3V and a peak up to 9V but then the fuse was gone.

Learned my lesson now (I think). I'm glad I had bought a 5 pack fuse... I will try to get another cable and try to find pictures to build the circuit above.

If someone has picture of the circuit above built would be great... the way I read is one 1K resistor then a transistor and another 1K resistor... I don't think this is right so would appreciate if anyone could post a picture of the circuit.

Thanks

[Kilrah]

Inserting a jack slowly isn't a good idea as you've seen - jacks are crude connectors, and during insertion/removal will short contacts together. When it's quick enough it's more or less ok, but still one should not use jacks for power in the first place. Those radios normally don't have power on the main contacts, but only on the insertion detect contact - so if done well that contact should be isolated and there should be no shorting. Looks like the DX7 doesn't have it "done well".

Now to the trainer cable - Sleeve is ground, tip is signal. Middle (if present) is not connected.
That schematic (which by the way isn't mine - i think the first time I saw it it was actually posted by showmaster ) would see the transistor's emitter connected to ground, and base - collector "in line" with the signal wire with 1k res inbetween.
I've never tested it myself, but read about several "success stories".

[ShowMaster]

It was posted for me a year ago by Gruvin if I remember. I admit Iobes on to other projects at the time Ann's just used my spare 9x as the trainer.
Hopefully seine will post that it works.
I'll try it ASAP since I never followed up on it. The issue is that like JR, the Spektrum ppm out is an open collector circuit that is also capacitive coupled. This messes with the reference to ground as well as being a 3 volt or less level.
A search by me has never found any JR or Spektrum trainer input and output circuit schematics to see what's actually going on. Maybe someone has this info that can share it?
SM


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