Spekky advice please

Like B&Q for homebrew radios
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Phil_G
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Spekky advice please

Post by Phil_G » 24 Jan 2019, 21:06

A potential Retro-R/C enthusiast has asked me what module he should buy in order to build a Spektrum-compatible tranny. The usual answer of 'Orangerx DIY' is no good as HK seem to have been out of stock forever. There is the Futaba-cased Orangerx module but then you need aerial extension leads and you have to be careful they're the right connectors (orange are different to everyone else)(except assan & quanum). Confusingly some of these remap the channel order from AETR to TAER in the firmware and some dont, and its pot luck which firmware you get.
Then there are the multiprotocol modules but its a minefield of different types, range claims, different manufacturers and different levels of nerdiness to get them going. He wants plug & play, no loading firmware or configuration to do. And he wants two of them. What would you Spekky types recommend for him please?
Ta
Phil

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PaulJ
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Re: Spekky advice please

Post by PaulJ » 24 Jan 2019, 21:55

Yes, supply of the Orange DIY is spurious and sometimes there are long periods when they are unobtainable but, in conjuction with your various emulators and encoders, they are so easy to use that I just click "Alert me" on the HK website and wait for them to come in. At the moment they are saying "Early February" so hopefully not long to wait now and when they do come in I will order three........ I have two Txs waiting for conversion and I will keep one in stock.

So yes, it is irritating having to wait but anything worth having is worth waiting for!

Paul

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_AL_
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Re: Spekky advice please

Post by _AL_ » 24 Jan 2019, 22:52

With the price of the modules these days it might be cheaper to buy an old DX4 or DX5 & rat the RF from that.

Al

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Phil_G
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Re: Spekky advice please

Post by Phil_G » 25 Jan 2019, 00:05

_AL_ wrote:
24 Jan 2019, 22:52
With the price of the modules these days it might be cheaper to buy an old DX4 or DX5 & rat the RF from that.
Thanks Al, unforch they're not ppm driven, they use a serial protocol at a weird baudrate, it has been documented but its not the plug & play module our guy is looking for Image

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Wayne_H
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Re: Spekky advice please

Post by Wayne_H » 25 Jan 2019, 04:05

Phil,

have you seen this - may solve your problem?
https://www.ebay.com/itm/Spektrum-DM8-m ... 0169.m2942
Cheers,

Wayne
Once a Retrobate, always a Retrobate............ ;)

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_AL_
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Re: Spekky advice please

Post by _AL_ » 25 Jan 2019, 12:26

Phil_G wrote:
25 Jan 2019, 00:05
Thanks Al, unforch they're not ppm driven, they use a serial protocol at a weird baudrate, it has been documented but its not the plug & play module our guy is looking for Image
Fair enough.
If it were me, I'd be looking for a 2nd hand Spektrum DM or Orange Rx module on the forums. That said, looking at Wayne's link, you might want to avoid any that were put in the rain for a pic :?
With so many moving to the all in one modules, there must be a few of the old Orange ones floating around.

Al

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Wayne_H
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Re: Spekky advice please

Post by Wayne_H » 25 Jan 2019, 12:47

Fair enough.
If it were me, I'd be looking for a 2nd hand Spektrum DM or Orange Rx module on the forums. That said, looking at Wayne's link, you might want to avoid any that were put in the rain for a pic .....
Al
Al - I thought that was Pommy sunshine :lol: :o
Cheers,

Wayne
Once a Retrobate, always a Retrobate............ ;)

Mike_K
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Re: Spekky advice please

Post by Mike_K » 26 Jan 2019, 17:11

Hi Phil

If he really wants an OrangeRx DSM2/DSMX DIY module, I've got half a dozen on the shelf, I could sell him one. I've also got a couple of the multiple protocol modules that have the firmware already loaded and ready to go if he'd prefer. But is it worth talking your friend out of using a DSM2/DSMX compatible module and to use a FrSky DIY module instead?

If he converts a transmitter and uses your Arduino firmware, it doesn't have multiple model memories, so it will probably be one transmitter per model. Therefore if he only converts one transmitter and uses a FrSky module, he only needs to buy a single receiver which isn't too expensive. I've got nothing against OrangeRx modules (both DIY and Futaba compatible) and have used them together with Spektrum DM8 modules with the case removed, the multi-protocol modules from Banggood and FrSky with equally good results, so he doesn't need worry about the protocol.

Out of choice I now use FrSky DIY modules as they are so much easier to obtain. And as my encoder has multiple model memories an OrangeRx DIY module is a pain in the neck if you have a mixture of DSM2 and DSMX receivers as it transmits on the last selected protocol and you are forever pressing the bind button three times to change the protocol back to what is needed. At least with the OrangeRx switchable Futaba modules you can set the switches to DSM2 and 22mS so that all DSM2/DSMX receivers will work without changing the modules protocol.

Finally a couple of years ago I did get a Spektrum DX5e 2.4 module working with an Arduino, but as I wanted 7 channels for many of my models, I didn't pursue it. There has been a far bit about using them on other forums, but many have had issues getting them to work with a 16MHz Arduino. The reason is the Spektrum module works at 125K baud, which is not available with a 16MHz ATMega 328. They set the baud rate for the nearest available which is 115K, but this actually gives 111K buad on a 16MHz Arduino (115K -3.5%). Spektrum DX4e, DX5e and DX6i all use 3.3V ATMega's at 8MHz. An 8MHz ATMega at 115K baud actually runs at 125K buad (115K +8.5%) so obviously is matched. The secret is to use a 3.3V 8MHz Arduino, there is plenty of processing power to do all the other bits of the encoder, maybe I should finish that project off properly so that Spektrum DX4e, DX5e and DX6i modules could be used for conversions.

Cheers

Mike

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Phil_G
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Re: Spekky advice please

Post by Phil_G » 26 Jan 2019, 17:32

Thanks all. He's quite willingly agreed to go Frsky so problem solved for now :D
Yes quite why Spekky used a non-standard baud rate always baffled me Mike its been a while since I looked at the DX4e modules, I'd always expected it to be an RS232 standard speed like 115 but I did follow the RCG thread where all was revealed, IIRC they initially thought it was 100k then found it was 125.
I'll have another read of the 328P datasheet as I just assumed the 3.3v and 5v uart clock options were the same - you learn summat new every day. Incidentally I wonder if anyone's used a Frsky XJT in a conversion yet, not heard of one. I think all the relatively 'poor' modules have faded away now, pretty much anything on the market now seems perfectly ok, take the Flysky RM002 for example - fourteen quid and superb range & reliability Image

Thanks everyone esp Mike for the offers but he originally wanted two Orange modules, and he's in Italy so I think better he orders his own and now he's decided on Frsky's we're all good to go.

Ta v much everyone Image
Cheers
Phil

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