openrcforums

Hello all,
this is my first post here.

I've just received my 9Xtreme and had to do a few mods to get it to connect to my DJT module for telemetry, without wires sticking out.
I'd like to share my solution as it might interest others.
This is not something new, I achieved this by piecing together other guides.

First you'll want to mod your DJT module to send its TX and RX through the unused pins of the JR module connector (the connector on the back of the remote that connects to the module).

Remove the two screws from two screws from the module, and solder a wire between the TX pin and pin 5 of the back connector.
Solder a second wire between the RX pin and the 2nd pin of the back connector, but put a 2K7 ohm resistor in between, that is a red-purple(or pink)-red color coded resistor. The resistor is not strictly necessary, but it allows you to still use the RX and TX ports on the back of the DJT module (it will override the connection to the transmitter). EDIT: A better mod of the DJT module is detailed here: viewtopic.php?f=95&t=3868&p=57121&hilit=#p57047 , where a 4K7 resistor and a diode are added to the TX wire. This makes it safe to use in a Taranis remote. Thanks Mike for pointing this out.

Now it's time to open the transmitter. Remove the four screws from the back plate, slide the power connector out of the plastic casing, and now you are able to lift and flip the back pcb.
This is the tricky part: you'll have to disconnect pins 2 and 5 from the ground. Use an xacto cutter knife to sever the connections going to the pins.
For more details on these steps, you can follow these instructions (first three screenshots only): http://openrcforums.com/wiki/index.php/ ... Sky_module

Now you can solder two wires from pins 2 and 5 to a male header pin. I glued this header to the side of the back plate, as shown in the picture. You can use hot glue or superglue, as long as it sticks. Then make sure to connect the WHITE wire of the 9Xtreme telemetry cable to pin 2 (RX from DJT), for which I used a red wire.
Connect the black wire to pin 5 (TX from DJT), I used a blue wire for this.
If you are smart, you use a black and white wire instead of a red and blue. I was not
Note that not all illustrations or pictures are mine, some are, others I have gathered from these other great sources:
http://openrcforums.com/wiki/index.php/ ... _Telemetry
http://er9x.googlecode.com/svn/trunk/do ... ryMods.pdf
viewtopic.php?f=126&t=7718&hilit=djt&start=150
viewtopic.php?p=103459#p103459
viewtopic.php?p=102836#p102836
http://www.smartieparts.com/shop/index. ... page&id=21


I noticed another mod on this forum that is similar, though a bit different too: viewtopic.php?f=26&t=7768


EDIT2: I'm adding complete basic testing instructions, for those who are new to the er9x software, as to me it was quite puzzling at first. Just for completeness I'll go over the complete instructions.
Now you will want to test whether telemetry works.

I tested this with a D8R FrSky receiver, of course it also works with a D4R. We'll be verifying whether we can see the RSSI from the receiver on the display of our remote. The RSSI is an indication of the signal strength between remote and receiver, it is a number between 0 and 100 (careful: it's not linear!). We test the RSSI because, without additional sensors connected (or a telemetry connection with a flight controller like a pixhawk), this is the only telemetry information that the receiver will transmit. A quick way to test the receiver is to connect a battery (I used a small 2S battery) to a 5V BEC, and plug the BEC into the + and - of one of the receiver channels (I plugged it in ch8). BE SURE to connect the polarities correctly! Failing to do so WILL destroy your receiver.
The first time you do this, the receiver and DJT module will have to be paired. Press with a screwdriver in the button on top of the FrSky receiver, then plug in the power.
Switch off the remote, hold the button on the back of the DJT module and switch the remote on with the button pressed. Now both modules should be paired. Switch them both off again, and turn them on the regular way (without pressing a button). The led on the receiver should be on continuously to indicate that a connection is made.

Hold MENU button, select "Model setup" (because telemetry settings can be customized per aircraft model)
Select "Telemetry" menu, verify that UsrProto says "FrSky", this should be the default
Press DOWN, and keep going through the menus until you see "Custom Display 1"
Add RSSI to this display (you can also add other things here but for testing we only need RSSI)
Continue with DOWN through the other menus
Verify that FrSky COM port is set to 1 (COM1), this should be the default.
Now you can EXIT out of this menu.

EXIT back to the main screen, now press the DOWN key until you see the first telemetry display.
It should show RSSI

If modifying your DJT, I would recommend doing it this way: viewtopic.php?f=95&t=3868&p=57121&hilit=#p57047.
Not necessary if you are only using it with the 9Xtreme, but it does let you use the modified module in a Taranis.
BTW, ersky9x is available to run on the Taranis.

Mike.

Yes, my DJT has both resistors

João

What about the schottky diode?

Mike.

I didn't solder the diode as I don't have a Taranis.. It's ok for the 9Xreme without the diode, right?
Thanks

João

Yes.

Mike.

MikeB wrote:If modifying your DJT, I would recommend doing it this way: viewtopic.php?f=95&t=3868&p=57121&hilit=#p57047.

Thanks for the tip! I don't have a Taranis transmitter so I was not really worried about that, but I'll see if I can update my mod in the future, just for the case where I do plug it in a Taranis.
With the information spread around the forum it's easy to miss new information and rely on outdated ones.

It sure is. The information will come together over time.

Perfect, just what I was looking for, I'll try it out, thanks!

Thanks for the post

Hey guys, thanks for the great post. I've been working on the mod and noticed strange behavior. Initially I only hooked up the TX side of things, wiring the TX pin to pin 5 in the module and then in the case connecting pin 5 to the black wire on the 9xtreme board. I'm getting a RSSI value, but it was only about 87 when the controller and the model were on the same bench. Also, I was getting values for TSSI even tho that pin wasn't connected to anything, but I did cut the traces for pin 2. Any idea what's goin on?
thanks

Both values are telemetry values and all telemetry values are sent over the connection you have made.
RSSI is the signal strength seen at the receiver and TSSI is signal strength seen at the transmitter.

The real test of RSSI is to put the Tx in range test mode and move away from the receiver. You should get at least 30 paces (yards/metres) before the RSSI drops below 45.

Mike.

MikeB wrote: For the XJT just connect the black wire for the telemetry connection to pin 5 (bottom pin, old antenna connection).
You don't actually need to cut any tracks on the back board for this as pin 5 doesn't connect to anything except the big antenna pad.
For a DJT (with wiring mods), you would need to cut the tracks for pin 2 on the back board,
and then wire the white wire to pin 2.
Mike.

I run the telemetry wires through the back radio case and connect them externally to the FrSky DJT or the XJT module pins.
Maybe Mike or João will have more info about connecting the DJT module telemetry wires internally through the 5 module pins.
For more info, see here: (viewtopic.php?f=126&t=8506) and (viewtopic.php?f=95&t=7182).

Bob B.

When using PXX (XJT) protocol, it seem to be normal to see the RSSI to jump around and read lower RSSI values (PXX protocol gives you RSSI and SWR data reporting).
When using DJT or the XJT as a DJT and using PPM protocol, the RSSI normally gives more stable readings.

Mike, because I run the telemetry wires through back of radio case, I may have forgotten this, my understanding has been
when using the DJT and XJT in protocol PXX (XJT) in D8 setting for D-Series receivers, the telemetry needs to have both telemetry wires connected, what is the answer ?
I also do not mod my DJT modules as they may be used in my Taranis also.

Bob B.

You only actually need the wire for the data from the DJT to the radio.
I have modified my DJT to include a schottky diode, then it does plug directly into the Taranis using the bottom pin for the telemetry data.

Mike.