Extra inputs for Devo Tx's

Adding inputs to the 7E comes up every so often, and has led to extra 2x2 or 1x3 and then 2x3 switches, but no extra analog inputs. It can be done, so lets talk about that.

First note that the 6s and 8s would also benefit from this, as the 10 and 12(s) are the only Devo Tx's with extra analog inputs. I'd even like some shoulder sliders or dials on the my 10.

Second, you can already use the trim switch features to get as many as 6 "analog" inputs. They aren't as fine as the sticks, but you can get up to 200 steps out of them, scaled pretty much how you like it.

So the current proposal is to hijack the PWM input facility. I've actually thought about that a lot, and like it because you can do it without having to open the Tx or modify the deviation to do it. Just set the PWM mode in the model setup to "Extended" and the number of channels, and they get added to the available inputs for use in mixes, etc. Downside is that you can't then use the PWM port for buddy boxing, head tracking, sims, etc. at the same time. Probably true of any implementation that uses that serial port.

I was thinking about designing a "cradle" that looked like a full-size Tx that the 7E/6S snapped into, and putting sliders/dials/knobs/etc. on it to taste. It would plug into the trainer port as part of snapping in. Maybe include a pass-through. The electronics could migrate to other Tx's as is, but you'd have to figure out how to mount them so they were usable.

So, any other thoughts on this?

I guess i kind of brought this one up.
I started talking about this more out of curiosity. I just started with toy quads, and bought a 7e and modified it (first nrf24l01, now also with the 2x3 switches, so my needs are currently covered ). As i'm spending time reading on what's available, i also noticed seeing request of being able to add (analog)channels to the lower range devo's in a lot of threads (or often remarks that the devo 7e lacks channels).

For me i immediately made the link to the current universal module that's under development. If you're making your own module, adding such channels would probably be fairly easy. However it's already in its final stages, so adding that now would be quite crazy.
Since only 1 internal serial port would now be needed for all transmitter modules, maybe a second module that does nothing but add channels would now also be possible. But i'm also wondering if there's much demand.

For me it was more of a curiosity question, i'm learning a lot about rc & about this project in particular, and knowing a bit about electronics & a lot about programming, i'm wondering what the next steps will be .

I guess somehow we are reaching a point where it doesn't make sense to add many more features to a 7e, since most people choose it based on its extremely low price. The step up to the Devo 10 isn't to big which gives two analog inputs, no more memory problems and no longer the need to do the power mod. The cost of (nice) two nice 3 way switches and a cradle (maybe 3d-printed? ) with electronics and good quality analog inputs should leave you at the price of a Devo 10. And those who picked the 7e due to its size wouldn't use an cradle either, I guess. The internal space in the 7e is to crammed up to seriously put in another serial input module together with the two additional RF modules many people put in.

I guess the only true benefit comes for the 6s/8s, since it has a nicer display than the 10, but they lacks analog inputs. So maybe we should just look at a way to internally add analog inputs to the 8s? Or swap the display of the devo 10 for a nice TFT...PB mentioned something in another thread he found a similar sized higher res display...

To sum it up, based on the price we have 7e as entry level, the next step up would be a 10 with more control but a mediocre display or, at a similar price the 8s with the nicer display but lacking inputs.

I'm also one of the people looking at this, my primary interest is in adding POT's and/or sliders to the 7E (mainly 2 POT's), not to be a dick at all, I love the idea and will support it any way I can regardless of where it heads but frankly I dont care if it's not cost effective overall, I love my 7E and tho I need a 10 badly (unless I / we get this working soon) it's not cause I think I'll like it more, it's purely cause I need the functionality, and again I love my 7E, it's size makes it easy to carry around and easy to reach all the controls and I like how it feels vs a full size Tx and it's weight and I just like it overall so if I can make it do what I need I'd MUCH rather have it over a 10 or anything else. In the end, if it costs me anything less that a devo10 costs I'm saving money, and I'm not alone, I'm sure there's lots of other people here on this site and on RCGroups that would be happy to pay a good amount for something like this over spending $150= on a devo 10 to gain 2 analog channels (assuming they've already added the 2x 3-way's), I do understand what you're getting at saying it wont be cost effective to someone who owns neither and has to buy a D10 or buy a 7E and the 2 switches and all this stuff too but it's not like people new to deviation would be the target consumer of this thing, it'd probably be about the same as the universal module (popular among us here already using devo and able to do the technical aspects of it, so not a huge group lol)

I have nearly everything I need to put together an arduino into a PPM converter to do this, and that is probably super simple, I'll probably find some existing code for that in about 3 minutes on google lol. All I need is the POT's, what is the range on the stock POT's on the devo10 and how many turns? Anyone got a pic of one or an exact replacement link so I can get the same thing so everything's compatible?

I'm just gonna open mine up and wire it in and power it from the battery but it will work the same plugging it in with it's own power supply. Only thing is I dont see how a pass threw would be possible, seems like you'll have to setup provisions for your processor (AVR or whatever) to accept another PPM input and then mix the external input (buddy box, head tracker ect) and it's own together and send it out as one to the devo.

Cereal_Killer wrote: .. over spending $150= on a devo 10 to gain 2 analog channels (assuming they've already added the 2x 3-way's).

Just to be clear, the Devo 10 is $120 these days, not $150. And you may only want two analog inputs, but you get two analog inputs with their four trim buttons, two more 2-way switches, a high gain antenna, a lot more room to add internal modules, the prospect of the universal module just plugging in, getting all of the Devo features, not having to worry about protocol files not matching the dfu, and not having to mod the thing to get those two extra 3-way switches and an output power suitable for larger models. Personally, I think that's not a bad deal for $60. Especially when I've got a 10, and have already run into cases where I'm using the trim switches and still want more controls. A gps-equipped quad with four+ flight modes, and a 2d gimbal plus wanting to control a camera will do that to you.

And beyond that, I now want a control that's more suitable for controlling a foresail servo than either the knobs or the sticks. A shoulder slider or dial, for instance. Anyone got a Devo 12 or Taranis for sale cheap? Really cheap, considering I've bought 3 yachts in the last two months....

But yeah, I love the 6/7e form factor. I traded my 7e in for a 6s to fly micro helis before the 2x3 mod was invented, because I was already past at the limits of the 1x3 or 2x2 mods. While I have some issues with the touch control on that small screen and the buttons not getting to all the controls because touch screen, I don't want to use the 10 for everything. Or go back to the 7e.

That I have two devos is one reason I really like the external box approach. Well, that and it gives me another excuse to do some 3d design work. A two-part design with a box with an arduino + battery and maybe a switch and charge port (gotta love the Adafruit boost boards) and a second low profile box with a set of Devo 12 shoulder controls that I could velcro wherever they were convenient means I could move it between the two. Not that I've wanted an extra analog input on the 6 yet.

Scrap this method, see working method starting on next page!

Nice plan like it a lot.

Another thought popped into my head....
Why not just add another core 7e $20/30 most if not all parts needed. stm32F103 Dev boards do have pads for flash memory on them, may need to reroute them. We know software is great

As mentioned previousl I think future is a universal ARM board + display adapted for deviation for the DIY Tx
We are now talking adding arduinos to walker a tx etc, are in troubles of memory etc.

If we could use an Mbed or Teensy or whatever ARM board with display possibly a board with audio and vibrator. We could make really diy tx could be fitted in any old tx.
www.adafruit.com/

Would expect the project to get more attraction and more developers when it is very universal and can be assembled using standard available modules.(no custom pcb's to be deigned)

Fernandez wrote: As mentioned previousl I think future is a universal ARM board + display adapted for deviation for the DIY Tx
We are now talking adding arduinos to walker a tx etc, are in troubles of memory etc.

If we could use an Mbed or Teensy or whatever ARM board with display possibly a board with audio and vibrator. We could make really diy tx could be fitted in any old tx.
www.adafruit.com/

Would expect the project to get more attraction and more developers when it is very universal and can be assembled using standard available modules.(no custom pcb's to be deigned)

www.aliexpress.com/item/STM32F103RBT6-RC...ard/32253083468.html

If you need more of the cart just say...

I'd be all over a 5$ solution (which is what the attiny would be) to have an analog pot or two.
I love the 7e for its size, when I go flying, I have so damn much stuff to carry already, I really don't want a full size transmitter on top.

Likewise

There is a little spare room left in mine even though it has the extra 2 boards and 2 switches, though hot gluing a small ish project box on its back and trailing wires through the mysterious rubber bung on the rear wouldn't be an issue

As I am a layman at this - are you talking about an additional board with 2 pots and it outputs these into the TX's PPM line as an input, thus adding them as extra chanels?
It would also need a bit more programming for deviation to get these extra inputs to become controllable meaningful radio wave outputs?

I can wield a soldering iron, but still need diagrams showing where to point it
Have only got this far due to the rather well laid out and documented recipes that I followed

Regards
Rob

Arakon wrote: I'd be all over a 5$ solution (which is what the attiny would be) to have an analog pot or two.
I love the 7e for its size, when I go flying, I have so damn much stuff to carry already, I really don't want a full size transmitter on top.

ACK...
Really like this game controller feeling with my 7e...
If I use my old Futaba FC18V3Plus (two sliders), now with a FRsky-DHT module, it's like a brick in my hands.

Fernandez wrote: As mentioned previousl I think future is a universal ARM board + display adapted for deviation for the DIY Tx
We are now talking adding arduinos to walker a tx etc, are in troubles of memory etc.

If we could use an Mbed or Teensy or whatever ARM board with display possibly a board with audio and vibrator. We could make really diy tx could be fitted in any old tx.
www.adafruit.com/

Would expect the project to get more attraction and more developers when it is very universal and can be assembled using standard available modules.(no custom pcb's to be deigned)

I'm not trying to force my method on anyone, nor am I trying to say "this is how it's gonna be or nothing", the way I'm tackeling this is purely the way I want to do it to my TX, if as a community people decide they like the way I'm doing it and want to turn it into a community project that's great, all my work will of course be open source and available for use as-is or just as a starting point for a more in-depth project however I'm doing it how I am cause I need a solution ASAP, I need to have this up and running in th next few weeks.

It willi use a custom PCB for sure, it will use the ATTiny84 and it will require drilling two holes in the TX case for the pots and wiring inside the case to the main board and tapping into power and the PPM line and majoring editing of the MUX and won't necessarily be plug and play. If no one else is happy with that solution and you guys want to do your own thing that's great to, but again I'm going the direction I am cause I don't have time to wait for a community developed solution to do something I can throw together in a short time with $15 worth of components and 2k worth of AVR code. My end goal is a workable solution as fast as possible.

Community projects take time, if I was waiting on the universal modual to be able to fly a model id of been pretty dissapointed (no offense to anyone on that project, I've been watching it and realize the work it took), I don't have time for a solution along those lines, I have a plane now that needs the two extra inputs and that's my main motivation for the AVR solution I posted above. After all the multi-mod started out as a simple and cheap AVR board and evolved till it was scrapped and developed into the universal module, maybe something along those lines could happen here...

robocog wrote: As I am a layman at this - are you talking about an additional board with 2 pots and it outputs these into the TX's PPM line as an input, thus adding them as extra chanels?
It would also need a bit more programming for deviation to get these extra inputs to become controllable meaningful radio wave outputs?

Yes that's exactly what I'm doing. There will be a small board inside the txt that has the attiny, two pots will get installed in the case and wired in, also power and the PPM output.

The signal will get send from it to the devo (internally wired to the trainer port's data line) and then you'll need to setup a MUX to add the two (or four or six, the max the 84 can do) channel onto the end of the output PPM by editing the mixer. Just really generally you'd set it to use PPM ch1 as output channel 7 and PPM Ch2 as output channel 8 and it'll just pass that data straight theew (but you can also mix them into other channels if you wanted)

robocog wrote: There is a little spare room left in mine even though it has the extra 2 boards and 2 switches, though hot gluing a small ish project box on its back and trailing wires through the mysterious rubber bung on the rear wouldn't be an issue

No need to go through the "mysterious rubber bung". The trainer port is already tied to the serial port we want to use for this. All you need to do is have those wires terminate in a mono audio jack that you plug into the audio port.

robocog wrote: It would also need a bit more programming for deviation to get these extra inputs to become controllable meaningful radio wave outputs?

It doesn't need any extra programming. Might be useful, but not required. Deviation already has the ability to take PPM input on the line that we're going to coopt for this and treat it as extra inputs. Go to model setup, select "Extend" for the PPM item, click on it and set the number of channels you want. They now show up a sources in the mixer, after the virtual channels. If you plug in a second Tx outputting PPM - a deviation Tx set to PPM protocol, or some other Tx in buddy box slave mode - into the trainer port, you can mix it's controls into your channel output.

Might be useful to add a hardware.ini option for "Internal PPM channels" If people settle on a standard way to do this. Except that 1) this interferes with PPM output, so kills buddy boxing and using simulators if it's on, so you want to be able to turn it off, and 2) the 7E is running really tight on code space now, and we've already started disabling some features on it that add convenience instead of functionality.

The other reason for adding code would be to not use PPM, which is an signal, but instead use some digital signal. Would make things faster and more precise. But the hardware can all be built and tested without doing any programming!

The real question is - who's going to do the work? That's what's going to determine what's going to get done. Once a working example of any of these things exists, it's easy to convert between them. Except for replacing the cpu board, anyway. I suspect there's lots of support for all the alternatives. Just needs someone to do the initial setup. I'm chasing other projects now, so hopefully someone else will do it before I finish them.

I've already got my simple add-on board ordered, I made it tiny (about .5x.75", the size of a typical add on RF moduleI). All it's got on it is the attiny84 (in the 14 pin SOP package, I'd like to use the QFN in the end but for initial testing I needed to be able to solder to the pins if something was wrong and I hate doing that to QFN's) plus the xtal and the two needed CAP's for it, another input/filter lcap and a bunch of via's around the edge in standard breakout spacing. It cost $2.40 for a set from oshpark and I should have them in about 10 days (oshpark has really been cranking out my orders recently!)
I'll be more than happy to simply release that, or to update it more (I'm sure have a few changes to make probay even before these get here lol) or to just keep using it for my need-it-now solution and start on something else for the project here. I have a couple of personal PCB based projects I'm working on now but I'd be more than happy to do the board / circuit design & layout for this as a community sourced project!

I work in eagle 7.3 and I'm happy to share my actual board files so you can make board edit's as is fit for your own wants and needed, not just the gerber's like a lot of "OSHW" stuff these days...

I believe adding analog pots to Devo 7e have already been done by Galee. I saw people at Taoboa are selling various kinds of mods to 7e, one of which is to add analog pots. Maybe you can take a look at his source.

item.taobao.com/item.htm?id=36473440719

Wow,
m.intl.taobao.com/detail/detail.html?spm...2.0.0&id=43511786397

160¥ is about $25-30 U.S.!

Edit: I've never bought from TaoBao before but I just submitted a buying request, not sure what the process it... I do hope the one that comes has all the screws in it LOL. I'm much more interested in their solution that using the product, if it's a good workable solution I'll just install it, I'm just guessing it's either arduino or atleast 328P based.



Edit2: The entire thing already modded is only 328Y, that's <$60 US, WTF didnt I just buy that from the start!?!

As far as I can tell (by using Chromes translate feature) the only language their firmware supports is simplified Chinese...which would be an added major learning curve :/
(like is wasn't already a bit of a steep one!)

Thanks for clearing that up about the extending the PPM...it's somewhere I have never explored TBH
Only time I have used PPM is for when using the TX on a sim...now it's all setup and seems to work with everything I have chucked at it I guess I had no reason to have a mooch in there

Do hope this pulls off...esp if its not going to be particularly expensive

Regards
Rob

Any progress here? I've recently revisited attempting something similar to the taobao.com mod above.

I've again been fiddling with PPM input after discovering the PWM gimbal I got was defective. Still waiting on some Arduinos on the slow boat.

I still can't figure out the DSC/trainer port of my 7e. Everything I've found says the 3.5mm plug's tip is signal, and the rest is ground. However, checking my plug out.....

The plug tip connects to the black wire, which is contrary to the taobao.com image above where the signal wire connects to one of the middle 2 white wires.
Additional info:
The 2 white wires (#3 & 4) connect to the ground of the plug. They are separated without the plug inserted.
The other white wire (#2) connects to the right side of the unpopulated pad. The opposite pad (left) connects to the black wire/ plug tip.
This is confusing the crap out of me.

Does anybody know the pinout of the plug on the 7e's main board? Anything I do will be internal, so I really have no need for the DSC jack.