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Author Topic: JR rf module pinout?  (Read 4939 times)

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Offline Andy Sayle

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JR rf module pinout?
« on: August 04, 2007, 17:11:32 PM »
Afternoon Mac_man,

I was just wondering if you could tell me (or at least confirm if the stuff below is correct!) the pin connections to a standard JR rf module?  I beleive they are usually 5 pin connectors, and if you look at the connector on the module, pin 1 is the upper most one.  That makes them as this:

Pin 1 -  PPM (or PCM) modulation input (I don't know the min/max voltages for the PPM/PCM stream though if you can share that info?!)
Pin 2 -  Unknown
Pin 3 -  Battery voltage?
Pin 4 -  Gnd
Pin 5 -  Unknown.

Of the two unknown pins, one of them must be the RF output to be passed on to the aerial.  I am not sure if Pin 3 sees the full battery voltage from the TX, or whether it is regulated at all inside of a JR tx?  Finally, is the PPM input stream at the battery voltage level, or a regulated level?

Any help you (or anyone else for that matter!) can offer would be much appreciated!

Cheers
Andy

EDIT:  Also, can you confirm if all JR radios when sending a PPM stream to the rf module, use a normally "high" signal, with each pulse being a drop down to 0 volts?
« Last Edit: August 04, 2007, 17:17:42 PM by Andy Sayle, Reason: Added a bit more :) »
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Offline Theaton56

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Re: JR rf module pinout?
« Reply #1 on: August 04, 2007, 22:53:02 PM »
Pin 1 is the modulation info (either PPM or PCM usually 0 - +5V
Pin 2 is a regulated 6V
Pin 3 is Batt Voltage fed from the Power Switch on a separate "wafer" (allows for DSC operation) at Full Voltage
Pin 4 is Gnd
Pin 5 is RF Output

Inside a JR set there are usually a couple of voltages...  Raw Batt Voltage, Main 5V regulated, 6V regulated, 3V lithium (if fitted) and a couple of -ve voltages on the 9X & 10X (for the contrast on the LCD).

Off the top of my head, I can't remember whether its a +ve going pulse or a -ve pulse....  can check on Monday for you.

:)

Offline Andy Sayle

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Re: JR rf module pinout?
« Reply #2 on: August 04, 2007, 22:59:44 PM »
That's fantatstic, Cheers :)  I take it most (all?) JR tx's use 9.6v nicad packs as a power source?

I'm going to be an even larger pain in the rear now, and ask if you can take a couple of measurements for me too if that is not too much trouble?

I'm trying to find out what the PPM modulation info looks like when it is churning out a 9 channel stream.  Things like the channel marker pulse widths, sync pulse width, and overall frame length.  I don't suppose you could post, or email if it is easier, a 'scope shot of the PPM stream could you?

I'll have to owe you a favour if you could :)

Cheers
Andy
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Offline Theaton56

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Re: JR rf module pinout?
« Reply #3 on: August 04, 2007, 23:03:31 PM »
^_________   Falls off chair laughing his socks off in a maniacal way....

IF I had a decent scope and a decent camera, I would be more than happy to help.  However....  it is not possible to take any timings with the scope I have. 

I'll email someone who has better equipment than I have and ask him to make the necessary measurements.

:)

Offline Andy Sayle

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Re: JR rf module pinout?
« Reply #4 on: August 04, 2007, 23:21:11 PM »
If you could do that, it would be much appreciated!

You are saving me from buying a 9 channel JR tx to poke around with, so I'd be more than happy to buy you a beer or two ;)

I thought everyone had digital storage scopes these days  ;D

Cheers
Andy
I can fix anything in the whole world, for I am armed with two rolls of Duct tape, and a rather large Hammer....

Offline Theaton56

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Re: JR rf module pinout?
« Reply #5 on: August 06, 2007, 01:01:37 AM »
Thats the least of my problems.......

With the garbage I have, I am amazed that I havent sent anything major back to JR for repair !

Offline cyclone

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Re: JR rf module pinout?
« Reply #6 on: August 08, 2007, 10:03:12 AM »
This might help Andy

Offline Andy Sayle

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Re: JR rf module pinout?
« Reply #7 on: August 08, 2007, 10:10:24 AM »
That's brilliant cheers!  May I ask if that has been taken from the RF module connection, or the Trainer port?  It looks like it is around 10v signal level (battery level I presume) which seems a bit high to be fed into the rf module :)

Thanks though, it is much appreciated.

Andy
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Offline cyclone

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Re: JR rf module pinout?
« Reply #8 on: August 08, 2007, 10:13:11 AM »
Taken at the rf module connector (rf module disconnected)

Offline Andy Sayle

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Re: JR rf module pinout?
« Reply #9 on: August 08, 2007, 10:18:57 AM »
Smashing.  From my measurements of that image, it is showing a frame length of ~22ms, and a channel marker pulse width of 400Ás.

One more question to anyone who happens to know, what is the maximum and minimum servo timings that a JR radio can send out?  I.e. the pulse widths that are sent to the servo from the receiver.  This would be with the TX set to its maximum possible end point, with full trim etc etc?

Cheers
Andy
I can fix anything in the whole world, for I am armed with two rolls of Duct tape, and a rather large Hammer....

Offline cyclone

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Re: JR rf module pinout?
« Reply #10 on: August 08, 2007, 10:29:23 AM »
Spot on 22ms and 400Ás (had to pause there to figure out how you typed that)

I'll measure the max and min width on the throttle channel when I get a moment.

Offline Andy Sayle

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Re: JR rf module pinout?
« Reply #11 on: August 08, 2007, 10:50:04 AM »
That would be great thanks!

Cheers
Andy

PS.  the "Alt" key is your friend :)
I can fix anything in the whole world, for I am armed with two rolls of Duct tape, and a rather large Hammer....

Offline cyclone

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Re: JR rf module pinout?
« Reply #12 on: August 08, 2007, 12:07:42 PM »
900Ás min and 2.10ms max (predictable I suppose with 1.5ms nominal centre)

I did try max everything but it wouldn't go past those, on the rudder channel.

Offline Andy Sayle

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Re: JR rf module pinout?
« Reply #13 on: August 08, 2007, 12:21:23 PM »
Fantastic,  Thanks very much for your help, it is much appreciated.

cheers
Andy
I can fix anything in the whole world, for I am armed with two rolls of Duct tape, and a rather large Hammer....

Offline cyclone

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Re: JR rf module pinout?
« Reply #14 on: August 08, 2007, 12:44:02 PM »
You are welcome.

Dare I ask what you're up to ?

Offline Andy Sayle

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Re: JR rf module pinout?
« Reply #15 on: August 08, 2007, 13:16:20 PM »
Of course!

To cut a long story short, I am really missing the programming and mixing options on my MPX evo 9 radio.  I have been using a DX7 radio for a while now on my smaller planes, but it doesn't really cut it for some of the mixes and control options I wish to use on some larger planes.  As I am now really liking the lack of interference, glitches and short aerials, I thought it would be quite nice to adapt a spektrum air module to work with my Evo radio.

Anyway, on the workbench, it is currently working, albeit only when I set the Evo to output 8 channels.  When I try for 9 channels, I am getting a lot of jitter in the servos, and dropped frames (as indicated by the spektrum flight log thingy).  I figured that this has to be down to the timing of the Evo 9 channel PPM signal, and it not matching up to what the JR Spektrum module is expecting.  As I don't own a JR radio, this makes it quite hard to get some decent readings for the timing of a JR PPM stream, but thanks to you and Mac_man, it is sorted now :)

The Evo radio in 9 channel mode uses a frame length of between 24.1 and 25ms (depending on whether the outputs are set to universal mode, or Multiplex mode).  The JR radio (as you know) is putting out a 22ms frame.  Everything else is pretty much identical, pulse width limits, etc.

I'm now going to knock up a circuit to test this out somehow (not sure how yet though!)

You did ask :) :)

Cheers
Andy
I can fix anything in the whole world, for I am armed with two rolls of Duct tape, and a rather large Hammer....

Offline slippyr4

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Re: JR rf module pinout?
« Reply #16 on: August 08, 2007, 14:39:56 PM »
Isn't DSM2 an 8 channel protocol?


Offline Andy Sayle

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Re: JR rf module pinout?
« Reply #17 on: August 08, 2007, 14:51:42 PM »
Not according to the module I have.  It quite clearly says on the front of it "9 Channels".  I have sent an email to Spektrum asking for more information on the input requirements to their air modules, as nothing is mentioned in the manual about things like input pulse durations, voltages etc...

So far I have managed to get it working great on 8 channels (on the work bench), and leaving it on for an hour with some servos cycling, revealed no frame losses or aerial fades recorded at all.  I'm hoping to get a few more tests done outdoors this week, and perhaps look at trying it out on a lightweight foamy to prove it works...

Cheers
Andy
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Offline cyclone

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Re: JR rf module pinout?
« Reply #18 on: August 09, 2007, 08:45:38 AM »
What's the frame length in 8 channel mode Andy ?

By now you're probably half way through programming a PIC to sort it all out.

Offline Andy Sayle

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Re: JR rf module pinout?
« Reply #19 on: August 09, 2007, 09:57:06 AM »
The MPX Evo frmae length when you have 8 servos assigned (channels) varies between 22ms and 22.8ms, depending on whether the servos are set to "MPX" format, or "UNI" format.  I did a bit more testing last night, and with everything set to UNI, it works perfectly.  When some servos (or all) are set to MPX, there is the odd jitter and frame loss seen.

The problem with writing abit of code to sort the signal out, and correct the MPX 9 channel frame to a compatible 9 channel frame (i.e. go from 24.1ms to 22ms) is that there is going to have to be a delay in there of some sort, which will slow down the response of the overall system.

I've not quite got my head round the best way to shorten the pulses yet, or indeed whether it is worth the effort for an extra channel :)  Suggestions are always welcome though!

Cheers
Andy
I can fix anything in the whole world, for I am armed with two rolls of Duct tape, and a rather large Hammer....

 

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