Devo7e work

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21 Jan 2013 15:05 - 21 Jan 2013 15:06 #5319 by vlad_vy
Replied by vlad_vy on topic Devo7e work
At any case it's not very simple task to modify Devo 7E module. Possible will be easier replace module with Devo 8s module and use any Wi-Fi antenna with U.FL connector or Hitec Optima replacement antenna (inside original Devo 7E plactic antenna).
Last edit: 21 Jan 2013 15:06 by vlad_vy.

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21 Jan 2013 15:55 #5323 by RandMental
Replied by RandMental on topic Devo7e work
Noticed how the price of a Devo7e has dropped since we discovered this HW limitation :)

Walkera DEVO 7E 7-Ch 2.4Ghz Telemetry Function Radio System
User Id: skyes_rocFeedback: 257 | 99.5%
Returns: Not accepted

Buy It Now $39.00 +$25.00 shipping

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21 Jan 2013 16:13 #5324 by PhracturedBlue
Replied by PhracturedBlue on topic Devo7e work
Well, the layout of the Devo7e module is completely different from that of the Devo8/10/12 module. But they could easily replace the diode with a shunt for >10mW Txs I guess for future designs.

The CYRF6936 has a max output of 4dbM which Seems to correspond to the pre-antenna info listed on the FCC page for the 7e

The Devo10 docs show that value to be about 12dBm higher which sounds right given that they don't run the CYRF chip at full power in the Walkera firmware.

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21 Jan 2013 16:20 #5325 by PhracturedBlue
Replied by PhracturedBlue on topic Devo7e work
FYI, here is an image of the module with the shield removed. the diode in question is just below the xtal
Attachments:

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21 Jan 2013 16:26 - 21 Jan 2013 16:27 #5326 by Xermalk
Replied by Xermalk on topic Devo7e work
So, theoretically one could make this a >10mW Tx if one could remove the metal cover and add a small drop of solder over the entire diode? (Easier but not as good as soldering a wire over it)
Last edit: 21 Jan 2013 16:27 by Xermalk.

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21 Jan 2013 17:09 #5327 by PhracturedBlue
Replied by PhracturedBlue on topic Devo7e work
Probably yes. That picture is deceiving though. Those are really small parts. I probably wouldn't want to do anything without magnification. Also, getting the shield off was more work than I expected armed with my 150W gun and a solder-sucker and solder-wick, I still had trouble cleaning the pads enough to get the cover off. My gun is old and was being quite finicky, so that may be part of it.

I'm planning to take the diode off and replace with a shunt to see what happens, but no need to do that right at the moment.

Also note that there are all sorts of impedance matching issues to take into account. It is actually possible that shorting the diode will actually make reception worse. I'm assuming that won't be an issue though, since they use the same antenna for Rx

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21 Jan 2013 17:23 - 21 Jan 2013 17:26 #5328 by Xermalk
Replied by Xermalk on topic Devo7e work
Hrm, think ill stay away for now. Though i do have a very good magnifying lamp, but crappy soldering iron.

What would happen if one heated the entire shield and then lifted it of,
or would the heat damage something?

Im guessing the V911 flysky module would have no issues with 100/150 mW though?
Last edit: 21 Jan 2013 17:26 by Xermalk.

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21 Jan 2013 17:36 #5329 by PhracturedBlue
Replied by PhracturedBlue on topic Devo7e work
Th V911 module will not be affected by this limitation on the CYRF module. I'll try to get you pin-outs tonight.

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21 Jan 2013 18:35 #5333 by PhracturedBlue
Replied by PhracturedBlue on topic Devo7e work
FYI, I think it is very unlikely that Deviation had anything to do with the design of the 7e transceiver. The 7E was qualified by the FCC in August which is when we did the 1st official release of Deviation. Before that, we had publicly discussed the power output, but I don't see there being sufficient time to design and validate the transceiver board on the 7e in response to our findings.

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21 Jan 2013 19:23 #5336 by quique65
Replied by quique65 on topic Devo7e work
Hello,

I've just successfully tested your last commit with a SUPERFP and power output at 100mW. No disconnection on flight. I can't check the range because I'm flying at home but I suppose that is similar to the original, so I hope it's ok for small helis.

I have an older WK-2402 TX. Do you think that would be possible to use their module on the 7E?. I've attached the FCC ID document with internal photos.

Thanks in advance for your opinion.

Regards,
Enrique.

File Attachment:

File Name: WK-2402.pdf
File Size:394 KB
Attachments:

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21 Jan 2013 19:52 #5337 by FDR
Replied by FDR on topic Devo7e work
Not likely.
The WK-2402 is 10mW and has no amp at all, neither it has telemetry...

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21 Jan 2013 20:18 #5339 by PhracturedBlue
Replied by PhracturedBlue on topic Devo7e work
Inside the house, '100mW' is probably fine. outside I would use '150mW'
'100mW' in Deviation will give you ~1.5mW power actual
'150mW' in Deviation will give you ~7mW power actual

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21 Jan 2013 20:27 - 21 Jan 2013 20:36 #5340 by Xermalk
Replied by Xermalk on topic Devo7e work
7 ? ouch, i wonder how that would work with my master cp.
Mind making a Guesstimate on how long the range would be on a Master CP with 7 mW?


Anyway, im guessing this is what we would need to upgrade the range?

www.ehirobo.com/shop/product_info.php?products_id=11530

Edit: Hrm, only 7 solder points on the 7E Module? the 8s one seems to have 10
Last edit: 21 Jan 2013 20:36 by Xermalk.

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21 Jan 2013 20:48 #5341 by PhracturedBlue
Replied by PhracturedBlue on topic Devo7e work
7mW is from the FCC docs. I have no idea what it means for range. I do have a USRP which probably can be used as a spektrum analyzer, but I have no way to calibrate it for absolute measurements

Yes that 8S module is the one you'd need. You only need 7 pins to hook up the 8S module.

The pins are:
Power, Ground, MISO, MOSI, SCK, CS, RESET (though I don't know the order on the 7e off the top of my head)

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21 Jan 2013 20:56 - 21 Jan 2013 20:56 #5342 by sbstnp
Replied by sbstnp on topic Devo7e work
I think this antenna could be compatible with the Devo 8S module socket:

www.hobbyking.com/hobbyking/store/__1666...r_antenna_15_cm.html

I have 4 of them on the way, but it'll be another week or so before they arrive so I don't know for sure.

Devo 10 + 4in1
Spektrum Dx9
FrSky Taranis + TBS Crossfire
Last edit: 21 Jan 2013 20:56 by sbstnp.

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21 Jan 2013 21:07 - 21 Jan 2013 21:09 #5343 by Xermalk
Replied by Xermalk on topic Devo7e work

sbstnp wrote: I think this antenna could be compatible with the Devo 8S module socket:

www.hobbyking.com/hobbyking/store/__1666...r_antenna_15_cm.html

I have 4 of them on the way, but it'll be another week or so before they arrive so I don't know for sure.


Hrm i have a few 2.4 ghz antennas left over from routers and usb adapters, one of them should have a proper connector. Actually, that connector looks exactly like the ones used in every single laptop wifi module. i can likely steal one of those from a old decommissioned laptop.

Edit, BTW Pb could you take a photo of the soldering points with a ruler next to them. Id like to get a feel for the scale.
Last edit: 21 Jan 2013 21:09 by Xermalk.

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21 Jan 2013 21:47 #5346 by SadSack
Replied by SadSack on topic Devo7e work
If you want to give yourself a chance at removing shielding with modest tool set why not give this a go www.anticsonline.co.uk/533_1_1671854.html
it's same product as www.zeph.com/lowmelt.htm without industry pricing! Sure in US there's something like it at your local hobby shop.
Works well at removing 100 pin mcus :whistle:. Just need to use more flux and clean it all off after, flux/solder braid. If you don't have braid you could use old usb lead strip it you'll see what i mean or coax has better copper braid but mostly on old stock if you have any.

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21 Jan 2013 21:53 #5347 by quique65
Replied by quique65 on topic Devo7e work

PhracturedBlue wrote: Inside the house, '100mW' is probably fine. outside I would use '150mW'
'100mW' in Deviation will give you ~1.5mW power actual
'150mW' in Deviation will give you ~7mW power actual


Ok, changed to 150mW. Thanks.

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21 Jan 2013 21:55 #5348 by quique65
Replied by quique65 on topic Devo7e work

FDR wrote: Not likely.
The WK-2402 is 10mW and has no amp at all, neither it has telemetry...


Thank you. Ordering a 8S module...

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22 Jan 2013 01:00 - 22 Jan 2013 01:06 #5350 by RoGuE_StreaK
Replied by RoGuE_StreaK on topic Devo7e work
Might not need the module hack if an antenna hack is used? I'm not quite sure how the power/antenna gain thing works, but there's a post describing an "upgrade" of the antenna of the devo6:
www.rcgroups.com/forums/showpost.php?p=21025317&postcount=73
www.rcgroups.com/forums/showpost.php?p=21194370&postcount=214

PB, any pics of how the antenna cable is connected? I kinda like the cute little stubbytenna, but would be interesting to see if we can come up with a standard swap-out method that is doable by anyone with basic skills.
"Ideally", I'd like to be able to swap antennas depending on how much range is required, and how portable I want it to be. Seems most cheap antennas on ebay, and spare ones from routers etc., use an "RP-SMA" screw in connector, would be cool to have one of these fitted in the antenna location that you can swap-in whichever antenna you want?

eg.
$1.30 for an IPX to RP-SMA adaptor (if plug on board rather than solder)
http://www.ebay.com.au/itm/190766782598

$1.80 for a 7dbi antenna
http://www.ebay.com.au/itm/180424715087

$2.50 for a 16dbi megatenna
http://www.ebay.com.au/itm/251211302498

~$4 for a 2.15dbi stubbytenna
http://www.ebay.com.au/itm/300554009601
Last edit: 22 Jan 2013 01:06 by RoGuE_StreaK. Reason: added more devo6 antenna

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