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Old Nov 24, 2009, 02:59 PM
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jakesterama's Avatar
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Spektrum Module mod - Aurora 9 related

A few people have asked about Spektrum releasing a 9 channel (or more) module for the new line of Hitec radios like the Aurora, but has anyone done a mod to any existing module?

Hitec says that the new 2.4GHz is compatible with the older transmitters, but the older modules will not be able to work with the A9 because of the extra pins in the way, BUT it still has the old analog PPM output on the pins, in the same position. Couldn't you just cut out the material where the new digital pins lineup? See my master MSPaint skills.

I am thinking about modding a JR module to get the full 9 channels, but this might be a quick and easy alternative for those who only want/need 8.

I contacted Spektrum about a Hitec Aurora 9 specific module and they said

Quote:
Originally Posted by Horizon
Jacob, at this time there has been any plans or announcements for a module that will fit in the Aurora 9, but since this is a new transmitter we may have something to offer in the future. Please check back in a while and see if we have something then. Hope it helps and have a great day.

Thank You
References-
Aurora 9 Mixes, Setups, Tips, Undocumented Features
http://www.rcgroups.com/forums/showp...postcount=1078
http://www.rcgroups.com/forums/showt...5#post13086515
http://www.rcgroups.com/forums/showt...0#post13580320
http://www.rcgroups.com/forums/attac...4&d=1244825655
http://www.rcgroups.com/forums/showthread.php?t=1106052
http://www.rcgroups.com/forums/showthread.php?t=907994
http://www.rcgroups.com/forums/showthread.php?t=387442
http://www.rcuniverse.com/forum/fb.asp?m=6476841


EDIT / UPDATE - it turns out that the Aurora 9 does NOT have the old Futaba pins, but instead only 5 pins in a whole new location.
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Old Nov 25, 2009, 06:00 PM
Never enough RC time.
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Nothin? Man, it seems like there is both ends of the spectrum in these parts; people who want to build their own radios and those that just ask "IS THE X9303 OR 9C BETAR?!" and no place for the casual tinker-er like me...
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Old Nov 26, 2009, 08:24 AM
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You just have to hit on a topic with more wide-spread appeal. When you start talking about cutting away some of the circuit board on a working radio, you probably lose a lot of people's interest.
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Old Nov 27, 2009, 09:34 AM
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If you do try to mod the DM9 module, you'll also have to deal with inverting the PPM signal, DM9 is meant to work with positive PPM, the DM8 would work since it is meant for negative shift PPM.
It's a shame they didn't do it like Futaba with the 10C modular. They left the door wide open to use it with any Futaba compatible conversion module, or your old 72Mhz Futaba compatible module, what where they thinking
I think most folks looking at the A9 will be going with Hitecs 2.4Ghz
Pete
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Old Dec 01, 2009, 02:44 PM
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Hey Jake,

I just took a look at some pictures of a opened-up DM8 module and I think this would be an easy mod. The circuit board looks like a simple double-sided layout with nothing but straight board near the module connector.

I think we can get past the physical interference by drilling a few 1.0mm holes, precisely placed, to allow the digital pins to pass through the board. We would also need to enlarge the keyhole (or drill cutouts) in the bottom plastic module casing for the same reason.

Please see attached pictures for the areas circled in red.

Let me know if you have any success with the DM8! I'm itching to get an A9 (it's light-years ahead of the current Spektrum offerings), but I'm knee-deep in AR* receivers already.

[Credit to rc Tricks for the DM8 images]

Cheers,

Victor
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Old Dec 01, 2009, 03:54 PM
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Don't lose sight of the fact that the DM8 module is designed for an input voltage of 9.6V nominal. If the voltage after the internal VR in the module is less than the nominal 7.2V that the Aurora uses, then it may work. But never ASSume.
Good luck,
Pete
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Old Dec 01, 2009, 06:29 PM
Never enough RC time.
jakesterama's Avatar
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Quote:
Originally Posted by dmccormick001 View Post
You just have to hit on a topic with more wide-spread appeal. When you start talking about cutting away some of the circuit board on a working radio, you probably lose a lot of people's interest.
lol, I guess you are probably right. But it is only cutting away on the less expensive module

Quote:
Originally Posted by pilotpete2 View Post
If you do try to mod the DM9 module, you'll also have to deal with inverting the PPM signal, DM9 is meant to work with positive PPM, the DM8 would work since it is meant for negative shift PPM.
It's a shame they didn't do it like Futaba with the 10C modular. They left the door wide open to use it with any Futaba compatible conversion module, or your old 72Mhz Futaba compatible module, what where they thinking
I think most folks looking at the A9 will be going with Hitecs 2.4Ghz
Pete
I like Hitec's 2.4 offering, plus with the deal they are running through March (A9 + 9ch RX + free 7ch RX + $35 7ch RX) it is a crazy good deal! I just want to keep Spektrum for my bind-n-fly and micro receiver birds.

Inverting the signal shouldn't be too much of a hassle with a simple transistor and resistors.

Quote:
Originally Posted by ragamofyn View Post
Hey Jake,

I just took a look at some pictures of a opened-up DM8 module and I think this would be an easy mod. The circuit board looks like a simple double-sided layout with nothing but straight board near the module connector....
Dang, after seeing that I really want to order up an A9. Maybe I can dip into the house-down-payment-fund without the girlfriend noticing....

Quote:
Originally Posted by pilotpete2 View Post
Don't lose sight of the fact that the DM8 module is designed for an input voltage of 9.6V nominal. If the voltage after the internal VR in the module is less than the nominal 7.2V that the Aurora uses, then it may work. But never ASSume.
Good luck,
Pete
Oh ya, I don't think I would blindly plug it it in, I would probe and test first. Where do you find this info? I seem to search and search, and all I get is contradicting statements and half-truths.
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Old Dec 01, 2009, 08:10 PM
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OK, on the voltage issue, the transmitters the DM8 is designed for are all 8 cell radios. The Aurora is a 6 cell radio, as is the Airtronics SD-10G and the new Futaba 8FG and 12FG.
Pete
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Old Dec 02, 2009, 12:22 AM
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So are the modules usually expecting an exact input voltage, or are they adaptive enough to use any voltage in a range? i.e.

5.5V < V+ < 10V
positive pulse > 50% V+
negative pulse < 50% V+

I am trying to dig up some dirt on DM8 mods but all I find is 100 different ways to route the antenna internally...
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Old Dec 02, 2009, 02:17 AM
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My bet is that "U1" (on the underside of the DM8 module, see the pictures I attached earlier) is the voltage regulator. I'm guessing that the middle pin is ground, the pin connected to C2 is voltage in, and the pin connected to C3 is voltage out. Just speculation: I don't see a part number on that sucker.

Victor
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Old Dec 02, 2009, 02:27 AM
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What I find somewhat interesting is that all the Spektrum DSM2 modules I've come across seem to be the X1TXN. I'm guessing that this is for the 2.4GHz RF radio module itself, vs. the transmitter logic, which is probably that fairly-beefy SMD that has the "V22" sticker.

If the X1TXN is common to all Spektrum transmitters, then perhaps we can infer some commonality between transmitters. The cheapest that I've found to use this module is the plastic 4-channel transmitter that is included in the RTF versions, and this unit (like the DX6i) uses 4 x AA batteries... so it's probably safe to assume that the radio module runs on less than 5.5V.

I just read in another thread that the Low Voltage alarm on the DX6i comes on at 4.3 volts -- so maybe the radio module's Vin is 3.3V-4V?
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Old Dec 02, 2009, 10:00 AM
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I think you might have hit the nail on the head Victor. Looks like U1 is a Micrel 500mA 3.3V regulator, but only appears to be the power for the module, the PPM signal is passed directly to the main chip. This seems to be alright though, people have fed the 6 cell EVO's PPM into the module and all is good. I suppose lowering the voltage to a point is A-OK, but I am not sure about raising it.

http://www.datasheetcatalog.com/data.../MIC5209.shtml
http://www.rcgroups.com/forums/showthread.php?t=690828
http://www.rcgroups.com/forums/showthread.php?t=826539
http://www.rcgroups.com/forums/showthread.php?t=682256
http://www.rcgroups.com/forums/showthread.php?t=959625
http://www.sokoll.net/doku.php/pastimes:rc:mpx:spektrum
http://www.rcuniverse.com/forum/m_64...tm.htm#7243696
http://rctricks.altervista.org/archives/1499
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Old Dec 02, 2009, 02:51 PM
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Sorry for the novice question, but why doesn't PPM have a well-defined voltage standard like 3.3V CMOS, 5V CMOS, or 12V TTL? Shouldn't PPM be within a known range of reference voltages to ensure compatibility?

Victor
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Old Jan 22, 2010, 11:04 PM
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If i'm reading this correctly the middle picture is showing the red, black and white wires attached to the last 3 pin outs with red as positive. black as negative and white as PPM. this is the futaba DM8 module? I want to put this module in a 7CAP, I know the wires in the 7CAP just need to make sure of the DM8 module.
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Old Mar 05, 2010, 11:16 AM
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Quote:
Originally Posted by davecrash View Post
If i'm reading this correctly the middle picture is showing the red, black and white wires attached to the last 3 pin outs with red as positive. black as negative and white as PPM. this is the futaba DM8 module? I want to put this module in a 7CAP, I know the wires in the 7CAP just need to make sure of the DM8 module.
Any more information on this. Looking to do the exact same thing with my 7CAP. From the pinout jakesterama sent, looks like we only need to interface to pwr, gnd, and pulse signal.

It is the RF Out that I don't quite understand. I don't think the DM8 is actually sending RF through that connector. It must be some sort of ACK signal to let the controller know that the RF module is enabled. So since this RF OUT signal is an output from the DM8 to the controller, then we don't really care about it with the 7CAP.

The only small bit of information that is missing is the voltage coming out of the Futaba module based controller. Or, what voltage range can the DM8 accept. The pulse train coming from the controller should be pretty standard but would be good to know again what voltage level the Futaba module based controller is putting out, and what the DM8 can accept.

I can put a scope on my 7CAP lines and verify they are the same once we find this information.

I'll keep researching, and if anyone else has any input, let us know.

Thanks
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