RC-USB Joystick Files - Page 9 - RC Groups
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This thread is privately moderated by Malc C, who may elect to delete unwanted replies.
Nov 02, 2007, 07:19 PM
Registered User
What version of the interface have you built ?

What do you mean "i cant do this work" - do you mean you've built one and it doesn't work, or do you you mean you can't program the chip ?

Does the DX7 output in PPM mode and not PCM - check the settings of the transmitter
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Nov 02, 2007, 09:34 PM
Registered User
Malc I have built the interface of Alessio: RC Joystick NG≤ 3.3.3 and it work great with a Futaba radio. But when I connect the interface to Spektrum DX7 it doesnt work.

I cant find where in the Spektrum I can change the signal output to PPM.

Dou you know if this is posible? This interface is Spektrum compatible?

Josť Luis
Nov 03, 2007, 04:56 AM
Registered User
Personally I don't know if the Spektrum has a PPM or PCM output from its trainer port, orr how to change it if it has this option.

If the interface works with your Futaba then there is nothing wrong with the interface as it will be decoding the PPM signals just fine, which would suggest that there is some compatibility issue with this model of transmitter. It also might be worth dropping Alessio a mail to see if he can help
Nov 04, 2007, 11:29 AM
Registered User
I tested my Spektrum with PPJoy + SmartPropoPlus (SPP) and work.

This is what I see:

In the SPP I put in Modulation:

Type: PPM (Generic)

Now for the Futaba in Shift Polarity I put Positive and it work.

For the Spektrum I put Negative and it work.

This is the only diference: Positive/Negative.

This is simple for our interface.

Supose in Futaba
pin 1 is GND
pin 2 is Signal

For the Spekturm
pin 1 is Signal
pin 2 is GND

All in the PPM imput.

And all works perfectly.

Thanks for all and I hope that I wrote will be helpful for someone else.
Josť Luis
Last edited by JoMebold; Nov 04, 2007 at 02:01 PM.
Nov 04, 2007, 06:01 PM
Registered User
I just wish to add that anyone experiencing issues should download one of the windows based oscilloscope applications such as http://sillanumsoft.altervista.org/download.htm

Hook up a lead from the sound cards line or mike input using screened cable, and connect the screen to whichever pin you suspect as being GND ( if its a round DIN type connector then this can be the circular outer shield - if its the square fitaba type then pin 2 should be GND) - then probe each of the pins to see if you get a trace

(more pin out info at http://www.mftech.de/buchsen_en.htm )

The trace should look something like

When you have found this trace, then make the interface connection lead to the same configuration (ie GND to GND and signal to input) and see what you get.
Nov 25, 2007, 08:37 PM
Registered User
what can I Revision the joystick name?
Nov 26, 2007, 04:21 PM
Registered User
1) - What version of the joystick are you building ?
2) - Check the hardware as it seems that the device has not been recognised
Nov 28, 2007, 09:55 PM
Registered User
Originally Posted by Malc C
1) - What version of the joystick are you building ?
2) - Check the hardware as it seems that the device has not been recognised
thank you
I think my hardware is ill
Jan 05, 2008, 06:19 PM
Registered User
JDill's Avatar
Is there a parts list that goes with the RC-USB8ch schematic? I did make up a list from looking at it but had some confusion. Most of the components are straight forward but I didn't understand 2 designations, 220R (R2) and 1K5 (R3).
Jan 05, 2008, 07:21 PM
Registered User
Hi Jeff,

The R designation is for Ohm, so in this case the 220R is a 220 Ohm resistor. The 1K5 means a 1500 Ohm (or 1.5K).

Hope that helps
Feb 13, 2008, 03:04 AM
Registered User

RC USB not working


I've built the RC Joystick NG2 and its is being recognised by the windows xp and game controller. i also have the led light on , on the circuit, but its not receiivng any input from my radio.

I ahve tried swap the radio output wires but still not working. I have both an old futuba 4channel and a DX7 spectrum.

Is there anything i can check. i will try also build the Malc C one to make sure i got it working i guess.

I have an old rc adapter but 4 channel only and it works fine with both radio, and im looking to fully benefit of the dx7 channel

Your help will be greatly appreciated

All spare parts on the circuit as exactly as specified
Feb 13, 2008, 12:43 PM
Registered User
The only suggestion would be to varify that you are getting a PPM signal into the interface. Simple way is to download one of the free soundcard based windows scope programs and probe the pins on the trainer port of the Futaba. It should be pin 2 on the DIN plug (if its the old round type). Other than that, check the board for track breaks, or shorts, and make sure all transistors are correctly mounted as some packages from some manufactures use different layouts (eg ECB EBC)
Feb 15, 2008, 11:46 PM
Registered User

Hi Malc C


I've build your version of the usb adapter and with my futaba 4 channel its working fine but not with my dx7 spectrum.

The led goes on and it works for 3 seconds and then nothing. I double check the mono jack, cable etc all seems fine, plug my futaba and its does work with it.

As u previously adviced i did download and use the windows oscilloscope and there is definately a ppm signal

Is there any issue with dx7 do i need to add a resistor etc for it to work


Feb 16, 2008, 03:48 AM
Registered User
Hi Fred,

Glad to hear that you have the interface working, at least with the Futaba. This confirms that the programming of the PIC worked well, and that your building of the board was sound.

Regarding the issue with the DX7, the only things I can think of is that either its sending pulse coded signals rather than pulse proportional, or the timing of the sync signal is out of range for the interface. Just to go over the development, I use a JR 3810 which has 8 channels which, along with Marks Futaba TX was used for testing. But since then (its now been almost two years since we took Allessio's code and modified it) there has been an explosion of RTF models and new transmitters, and thus we can't guarantee compatibility with some of the new technology.

You say you've scoped the output, try comparing the two outputs to see if they look the same or if the dx is repeating the signals quicker than the futaba. My recollection is that the interface is looking for a refresh every 20ms, if the dx is refreshing a ms or two sooner or later then this could be the issue. Maybe Mark could chime in here as he was the main drive behind the re-coding.
Feb 16, 2008, 12:21 PM
Registered User
I have realized the assembly of the interface with the chip 16c745, have recorded the file RCjoy-USB-Futaba.hex, the crystal of 6Mhz and it does not work, the PC does not detect anything on having connected the interface, any help?


P.S. I do not speak English write with a translator

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