How to use er9X with/as a buddy box trainer

er9x is the best known firmware. It has a superb range of features and is well supported by the community. Well worth trying out.
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ShowMaster
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Re: How to use er9X with/as a buddy box trainer

Post by ShowMaster »

Gruvins circuit installed in to 4066 ppm circuit does work and should be installed as it works!
I did breadboard up Gruvins circuit externally and it works. I changed the base input resistor to 330 ohms to keep the impeadance low. I also have the 150k from base to vcc to make it work.
I'm going to use a 7805 as the regulator from some battery source. A repeat of another post but it does seem to work.
No flying test yet.
SM
Last edited by ShowMaster on Wed Feb 29, 2012 6:13 am, edited 1 time in total.

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Re: How to use er9X with/as a buddy box trainer

Post by cre8tiveleo »

Excellent! Appreciate the info!
:)
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Re: How to use er9X with/as a buddy box trainer

Post by ShowMaster »

Strange but I have to report.
My circuit works but I notice it loads down to 5 v ptp pulse when connected so I'm going to try again. I'm thinking someone needs to build and sell a SMD version of gruvins internal circuit and we just install it internally as part of the upgrages. I'm not giving up but I keep running into issues and run out of time to spend on it.
I'm thinking of trying a 4069 hex inverter to keep the parts cound down if it'll work with the lower input PPM?
Ideas are welcome to get this a working 100% circuit.
SM
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Re: How to use er9X with/as a buddy box trainer

Post by Kilrah »

How about a simple single transistor inverter? The 9X can take both positive and negative PPM, right?

Image

Input the low level PPM into the base via the resistor, wire the "+12V" label on the image to the 5V rail, maybe replace that 1K resistor with a 10k, and send the output to where the PPM in would normally go. Will work with anything above 0.6 - 1V as input.

I've done it recently to hook a Graupner MX16's trainer output (that outputs a low 2V signal) to a Futaba for a friend, that was enough.
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Re: How to use er9X with/as a buddy box trainer

Post by MikeB »

I've just bread-boarded the following circuit which worked fine from one 9x to another, EVEN when I added a couple ov 10K resistors on the input so it only saw 2.5V pk-pk. I used components I had lying around.
It needed no power, and was wired between the two transmitters, not inside. The output does not need a pull-up resistor as the 9x as Master has an internal pull-up resistor. The 1K on the output is to protect the transistor if you plug in to the Master without switching it on. In this case, the Master will turn on due to the jack being plugged in, and drive a signal out.
The 39K resistor provides a high resistance to the incoming signal, so not loading it, and the 330K makes sure the transistor does switch off when the input goes low (below about 0.7V).

Since I would like to use the jack connector as an output from what is normally the PPM-input (for PPM16 and the as yet unimplemented PPM-SIM) it provides a good solution as it does not break the internal circuit.

(PPM-SIM is intended to provide a PPM output for a simulator using the PPM-IN pin to drive it, thus avoiding the problem of the tx module possibly loading the signal when it is powered off)
Trainer.png
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Re: How to use er9X with/as a buddy box trainer

Post by cre8tiveleo »

0V is Gnd? Just checking.. you know , for those who look at a diagram, then ask where 0v is on the pcb...

Student ppm> rr27 > t4 > r29 > ppm Master, r28 between student ppm (after r27) > gnd... that's it?

Going to try this with the Itouch/Android software... could be cool.

:)
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Re: How to use er9X with/as a buddy box trainer

Post by MikeB »

Yes, 0V is Ground.
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Re: Throttle range synch problem

Post by Galand »

I set up a buddy box link between two Er9x Tx's using the simple cable and disconnecting the module on the student Tx.
Works fine for all the control surfaces but not for throttle.
As soon as I flick the Trainer switch, the motor spins up even with the student throttle all the way down.
When I set the throttle range with the student Tx then the Master throttle does not start the the motor until mid range.
Apparently the throttle ranges between the two TX's is quite different.
How do I synch the two?
Thanks
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Re: How to use er9X with/as a buddy box trainer

Post by cre8tiveleo »

settings for trainer 'on' on master - trainer 'off' on student box?
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Re: How to use er9X with/as a buddy box trainer

Post by Galand »

cre8tiveleo wrote:settings for trainer 'on' on master - trainer 'off' on student box?
Yes to both. If not the control surfaces should not work either. Correct?
Edit:
I suspect that playing with the calibration settings could fix it.
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Re: How to use er9X with/as a buddy box trainer

Post by ShowMaster »

cre8tiveleo wrote:
ShowMaster wrote:Another trainer update...
I'll post the final working circuit after I've flown it and feel safe with it.
SM

Post it, post it, i want to use my android or Itouch as a slave box... :D

No seriously, I want to test the ppm out of those apps to see if they work. Is it the gruvin fix? (I think I read that)

Cheers!
I can't post it because I'm have issues. I could use some help here.
It seems that the TX I'm using for testing the external circuit is a dx7 and depending on the dc level the ppm pulses ride on from the dx7 my circuit works and then it doesn't? I can see the dc level the ppm out from the dx7 floats on a dc level that can be + 5 and floats down to + 3. At + 3 all my circuits work, but at + 5 they all stop?
I'm missing something the dx7 is doing to the ppm out but it's got me stumped. Everything works great, then it doesn't?
Does anyone have an idea of the dx7 or JR ppm output ppm circuit? It should be so simple to convert a 1.5-2v PTP ppm steam to 5 v PTP? I guess I'm going to have to ask/beg for help on this one. Gruvins 1 transistor internal mod I installed works with every TX so far. I'm thinking that is the best option for the 9X if your in a hurry for something that works.
I'm so bummed right now, sorry for the almost circuit. I'm taking the night off to think about it.
SM
More info
I just found posts saying the dx7 ppm signal is capacitive coupled so that's why the dc level drifts and my circuits works and then not. So the key is to convert it back to dc only levels again. Not my best area of experience.
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Re: How to use er9X with/as a buddy box trainer

Post by ShowMaster »

MikeB wrote:I've just bread-boarded the following circuit which worked fine from one 9x to another, EVEN when I added a couple ov 10K resistors on the input so it only saw 2.5V pk-pk. I used components I had lying around.
It needed no power, and was wired between the two transmitters, not inside. The output does not need a pull-up resistor as the 9x as Master has an internal pull-up resistor. The 1K on the output is to protect the transistor if you plug in to the Master without switching it on. In this case, the Master will turn on due to the jack being plugged in, and drive a signal out.
The 39K resistor provides a high resistance to the incoming signal, so not loading it, and the 330K makes sure the transistor does switch off when the input goes low (below about 0.7V).

Since I would like to use the jack connector as an output from what is normally the PPM-input (for PPM16 and the as yet unimplemented PPM-SIM) it provides a good solution as it does not break the internal circuit.

(PPM-SIM is intended to provide a PPM output for a simulator using the PPM-IN pin to drive it, thus avoiding the problem of the tx module possibly loading the signal when it is powered off)
Trainer.png
Mike.
It seems dx7 and jr's use capacitive coupling out for the ppm. Your circuit and many I've tried doesn't reference properly to ground for the digital data to be drive the transistor high and low. For the moment I'm stumped. Add a series cap in your base circuit and see what happens.
SM
SM
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Re: How to use er9X with/as a buddy box trainer

Post by MikeB »

Interesting, Gruvin's internal circuit is almost the same, just slightly different resistor values. It may be the capacitor doing the coupling gets charged up due to the different charge/discharge paths (39K+BE junction, 39K+330K the other way). Adding a diode to provide a better discharge path might help:
Trainer.png
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Re: How to use er9X with/as a buddy box trainer

Post by ShowMaster »

I'll try the diode Mike thanks for hanging in there with me.
Yes the charging cap is what's causing the trouble. For some reason the 4066 must champ the 9x trainer in and that makes gruvins circuit work so well. My circuit(s) externally all suffer from the input from the dx7 drifting from +5 down to 0v. If I watch my scope on DC I can see the drift. When ever the DClevel of ppm drifts to around 3 volts the circuit starts to work and stays working until it drifts higher or lower. I'm sure learning a lot about what I don't know.
I sure wish I could see a schematic of the dx7's ppm in and output circuits. Well kept secret so far.
Another reason the 9x is my favorite, FCC and Gruvins schematics.
I wonder if Spektrums circuits are in the FCC's archive to look at?
I'll report later today on your circuit and the diode idea. I do have a few spare 4066 SMD ic's if all else fails. I'm determined to make this work now just to learn.
SM
Excuse any typos on my iPod and big fingers
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Re: How to use er9X with/as a buddy box trainer

Post by MikeB »

The 4066 probably does clamp the negative voltage caused when the capacitor coupled signal goes negative. The diode above should work as well.
Mike.

Edit: Just tested this, it actually seems best with the diode, and without the 330K resistor, but this may also depend on the value of the coupling capacitor. The first pulse after the sync gap was slightly odd with the 330K in.
I tested with a 0.1 uF. Maybe this would work best then if you add the diode, remove the 330K resistor AND add a 0.1uF capacitor to the input. Then you are always capacitively coupled, which may be good as it will block the DC voltage from a system that outputs 9 volts.
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Re: How to use er9X with/as a buddy box trainer

Post by ShowMaster »

They this Mike. I used your last circuit but I found that if I put the diode (4148) directly across the output from my dx7 and low end JR Anode to ground as shown and elimanated R27 and R28 but added a 330 ohm resistor from the diodes Kathode to the 3904 base everything works and keeps working. The pulses look good but I'll revisit that later as I ran out of " lab time".
I tried a 4.7k and a 2.2k in the collector circuit but will try 1k later. Anything I added before the diode messed with the pulse shapes so I guess the other cap coupled ppm outs are OK with it as far as a 20 min test can tell. I think we're getting real close to a good working circuit here. I know from google searches others are looking for a good interface option for FPV and ppm outs being so low and funny. Many seem to bypass the coupling cap as a last resort I read. This may be the simple way to go, no mods.
OK, one last discovery. When I powered off my breadboard the output pulses from my circuit fell from 5 v PTP to 3.3G PTP but it still worked fine with the dx7 and JR? I have so many circuits on the breadboard that I'm not sure what path of parts may be making it work? I thought it may be residual power supply voltage so I disconnected the only power lead powering the 5 volt rail all my other circuits connect to, this is the only power source. I'm going to revisit it all and clear my breadboard of all parts and start over with the new circuit that seems to work and go from there. Is it possible that the 9x is back feeding enough voltage to power the collector circuit of the transistor?
Something to think about?
Self powered inverter buffer circuit, is it possible?
It was too early for wine so maybe I'm onto something with a clear head?
As always, I'll fly anything I build before I'll give it the go ahead but I'll post my progress, please feel free to explore my findings everyone.
SM
Last edited by ShowMaster on Sat Mar 03, 2012 6:31 pm, edited 1 time in total.
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Re: How to use er9X with/as a buddy box trainer

Post by ShowMaster »

Anyone have a recommendation for a good iPad app for quick schematic drawing? I'm not at the computer as much and I would like to post diagrams.
Please move this Rob if it's off topic here.
SM
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Re: How to use er9X with/as a buddy box trainer

Post by MikeB »

If you look closely at my circuit you will see there is NO power supply, the 9x provides a pull-up resistor for the collector internally to the processor (20K to 50K). I was getting the full 5 volt PTP from it. For a 'repeatable' circuit I would go for the 1K on the output, 4K7 is a quarter of the 'worst case' pull-up resistor, so you not pull the signal down as hardl, its not a pull_up resistor, it is in series with the output as a current limiter.
Having the diode directly across the input may load the student output too much for long term reliability, its like a short circuit for negative going signals.
330 ohms into the base is a little low, at 5V input you are trying to drive 13mA into the base, with a gain of 100, you only need a few microamps in the base to get the transistor turned on. 330 ohms will also discharge the coupling capacitor.
Did you try my circuit with the 330K (R28) removed? It worked fine in my testing with a coupling capacitor of only 0.1uF.

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How to use er9X with/as a buddy box trainer

Post by cre8tiveleo »

I cant remeber what its called, i use it, and yeah...

Here is a pic...




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Re: How to use er9X with/as a buddy box trainer

Post by ShowMaster »

Mike,
I built up your circuit and it does work. I'm using my dx7 as the trainer and an Flysky 9x with a stock
Ppm input circuit.
The only power source is what the dx7 and 9x provides. I had to change the 39k resistor to 10k to get it working, all other values are as you posted them except I'm using a 2n3904.
The amplified/level converted pluses (positive) are rounded at the top leading edges but the 9x seems to like them. I haven't scoped the 9x ppm pin going to the Frsky module to see if they look ok there.
I didn't remove r28 or try a .1 yet but will.
Any other comments on wave shape?
SM
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Re: How to use er9X with/as a buddy box trainer

Post by ShowMaster »

A user in RCG, garland, expressed some frustration that our discussion here about buddyBox issues got off on a technical path and his issues using 2 9X's wasn't addresed. This may be true and I'm guilty. It triggered a topic that's been on my mind since my first 9x. In keeping with that, but feeling that the technical discussion is of value, do we need to splinter off somehow the technical from operation trainer issues?
Rob is the best person to help with this I think. Once we nail the interface for using the 9x with any popular TX I think that discussion will end for the most part.
Ideas?
SM
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How to use er9X with/as a buddy box trainer

Post by cre8tiveleo »

Ban hammer!

There is a pm system here, any user could pm someone for help too. Wiki and the first 9 posts answer almost anything that could be asked. :)

Pm is a good thing.
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How to use er9X with/as a buddy box trainer

Post by cre8tiveleo »

Galand wrote:
cre8tiveleo wrote:settings for trainer 'on' on master - trainer 'off' on student box?
Yes to both. If not the control surfaces should not work either. Correct?
Edit:
I suspect that playing with the calibration settings could fix it.

The student 9x should be 'dumb' , non of the trims, setting, etc set on the student should cause the master to send anything, just stick inputs that you define on the trainer page of the master.
Do you have any inputs inverted on the trainer/slave unit? Mono cable?

Slave trainer setting should be off.

Plug the trainer in first, with power off, the power on the master unit, and plug that in.

What mods are on either transmitter?


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Re: How to use er9X with/as a buddy box trainer

Post by MikeB »

I thought I'd add this description of setting up the trainer (posted on RCG). Someone with a little time might like to 'polish' it and put it in the Wiki!

"Plug the two Txs together, with the MASTER on and the trainee switched off. When you plug the trainer cable in, the trainee will turn on.
On the MASTER Tx, go to the trainer menu (LEFT LONG followed by RIGHT).
When you move the trainee sticks, you should see the numbers at the bottom of the screen change, these are the trainee stick values as seen by the MASTER.
If you are using er9x on a 9x as the trainee, it is best to set up a 'student' model. This simply has the four sticks output on channels 1 to 4 with 100% weight. No other mixers are required.
Centre all four trainee sticks, including the throttle, use the graduations to set the throttle. The numbers on the MASTER should all be near zero. On the MASTER system, press the DOWN button until CAL is highlighted, now press MENU, all 4 numbers should now be zero, this has set the centre position of the sticks.
Move the trainee sticks from end to end, you want the numbers to go from -100 to +100. If they are all less than this (say -90 to +90), change the scale factor to get them close, increase the scale factor to make them bigger. For a 9x to 9x, I would expect the scale factor to be close to 1.0. To get them to exactly -100 to +100, you can either change the weights on the trainee tx mixes, or on the MASTER trainer input weights. (The master weights change by about 1.5% at a time). On the MASTER trainer menu, you can also map which trainee channels map to which controls.
When you have all 4 value going from -100 to +100, you are synchronised. If you wish, you can always make them go from, say, -80 to +80, then the student has less total movement available than the master, might take longer to get into trouble!.
You also set which channels are switched, and by which switch, so you could give a student only some of the controls initially.
Finally, in the selected model on the master, enable the trainer function.
When you switch the selected trainer switch, to allow the trainee to have control, the MASTER sticks are replaced by the trainee inputs. These are then input into the mixers set up on the MASTER system, so you don't need to duplicate the model on the trainee Tx."

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Re: How to use er9X with/as a buddy box trainer

Post by Galand »

I solved my problem by discovering that in the settings the throttles cannel was showing ADD instead of SUBSTITUTE. How stupid can you be!
As to diodes and resistors, we should find a way to separate that sort of discussion from the programming and mixing issues.
Not that diodes etc... are not interesting but it is a different issue IMO.
Mike B's explanation on setup and calibration of the buddy box is absolutely worthy of a Wiki posting.
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Re: How to use er9X with/as a buddy box trainer

Post by Brent »

Hi Guy’s,
I have a problem setting up the buddy system with my radios.
I have two ER9X’s, both of them with version r811 firmware installed.
I’ve set up the trainer tx as per the instructions and the trainee tx is setup up as a basic four channel airplane.
At the beginning of the instructions, it mentions having to do a hardware modification, but then in parentheses it says that this is no longer necessary thanks to Mike B’s fix through software. Quoted below!
“Before proceeding, ensure you've done the following.
(This step is no longer necessary if you are using r750 or later. Mike B. came up with a creative fix through software.)
For two flysky/turnigy 9x radios to function together in this setup, you need to do the ppm fix.
One way to do this is shown here.”
I have even let the RF module dangle on the trainee tx as mentioned and it does not work! My question is, What am I missing? Do I need to make this hardware change or not?
Thank you,
Brent
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Re: How to use er9X with/as a buddy box trainer

Post by MikeB »

On the trainee, go to the RADIO SETUP menu and enable PPMSIM. This is the software fix I came up with.
With that enabled, plug the cable in to the trainee, turn the trainer ON and plug the cable into that.
On the trainer, go the the TRAINER menu. Do the numbers at the bottom of the display change when you move the trainee controls?

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Re: How to use er9X with/as a buddy box trainer

Post by Brent »

What joy, I knew I had to be missing something, and no hardware PPM fix modification.
Thank you Mike for the answer and the quick response.

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