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Old Jan 08, 2014, 12:14 PM
RC beginner
New York
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ERGO-TX: low cost easy to build single stick rc transmitter

one of the funniest things ive ever seen was a fellow at the local AMA field flying a $5 3ch hobbypartz foamie with a $1000 futaba transmitter. complete with futaba neck strap and $50 tray. lol! if the guy had bigger more expensive planes it wouldnt be so hilarious but that was his only model. so i decided to see what could be done with minimum instead of maximum hardware and expense. browsing fmkits tracker thread (http://www.rcgroups.com/forums/showt...fmkit+nunchuck) i realized its hard to beat one of those $3 ebay wii nunckuck controllers as the basis for a low cost easy to build rc radio. and as a surprising side effect, extremely ergonomic to boot. easy to launch one hand which allows tossing the model with the other. very helpful when grass is your only runway.

enter "ergo-tx", a complete, low cost, easy to build, single stick radio based on a nunchuck and open source firmware. in fact everything can be done using off-the-shelf chips and parts with no need to get involved with mcu programming or any of that other stuff true geeks so love. one of the first versions i built used an m128 harvested from $9 hobbyking 9xr replacement board and pcbs from $15 flysky plug-in rf module. no flashing or mcu coding required.

however there are plenty of open source projects floating around if thats your thing. for example the popular er9x open source firmware is available which makes for just about the cheapest and most versatile ppm encoder possible as seen in my "core9x" project:

http://www.rcgroups.com/forums/showthread.php?t=1631369

for arduino fans patolin created an excellent rf encoder thread (http://www.rcgroups.com/forums/showthread.php?t=1817699) and midelics rf module project is very popular (http://www.rcgroups.com/forums/showthread.php?t=1921870). besides my core9x version ive successfully tested both of these with the ergo-tx hardware which is shown in the photo below.



attached is a circuit diagram showing how to connect the core9x or any of these modules to the nunchuck joystick. there are two possibilities for throttle control: use the built-in buttons or add a small trimpot on the side. ive tried both and must admit that for me the buttons worked best for controlling a plane. quite a surprise for someone who was brought up wiggling sticks. buttons can be implemented in a couple of ways: a simple capacitor circuit to bump adc input up/down or via software when connected directly to an mcu. the latter allows some pretty fancy throttle control features like setting upper/lower/mid levels, rates, limits, kill, etc using different button down times. ive implemented this on my tiny24 based encoder and as mentioned find it more ergonomic than a stick.

i also tried using the accelerometer chip in the original nunchuck circuit like fmkit does but for some reason didnt like it as much. somehow twisting and turning my wrist didnt feel that intuitive. maybe i need more practice.

the drawing below is not just a block diagram but actually a complete schematic with all components shown. if theres interest i can provide more links, photos, and info on things like component values and construction details. let me know. and if anybody else does actually build one of these this is a great place to show off your creation. i would love to hear about other ideas people have for low cost single stick transmitters too.




1/10/2014

added photos of er9x version. amazing to think this is a single stick version of turnigy 9x. uses same suntek xl7105 rf module for flysky compatibility but of course any type can be used. a friend prefers spektrum compatibility so he connected a hk orange dsm module. this one is powered by lipo instead of l-ion. if you look carefully you may be able to make out the protection board in that fullriver cell.



1/14/2014

photos of diy nunchuck cable adapter for those who might want to experiment with the built-in accelerometer w/o permanetly modifying it. 30sec with exacto and 6 header pins (polarize the cable by removing that unused middle pin).there are tons of arduino sketches out there for using that original internal chip. not all of them work due to compatibility issue so you might have to wade through a couple to find the right one. i was lucky to get it on the 2nd try. also added a pinout diagram. idk where the original came from but i modified it with some arduino names and colors. it worked for me but there may be differences among versions so if something dont look right speak up.




photos:
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Old Jan 08, 2014, 12:49 PM
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Nice,
which values for r1 and r2?Yes I'm more interested with details as theres are not many threads with single stick nunchuk.
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Old Jan 08, 2014, 12:55 PM
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Quote:
Originally Posted by dave1993 View Post
one of the funniest things ive ever seen was a fellow at the local AMA field flying a $5 3ch hobbypartz foamie with a $1000 futaba transmitter. complete with futaba neck strap and $50 tray. lol! if the guy had bigger more expensive planes it wouldnt be so hilarious but that was his only model. so i decided to see what could be done with minimum instead of maximum hardware and expense. browsing fmkits tracker thread (http://www.rcgroups.com/forums/showt...fmkit+nunchuck) i realized its hard to beat one of those $3 ebay wii nunckuck controllers as the basis for a low cost easy to build rc radio. and as a surprising side effect, extremely ergonomic to boot. easy to launch one hand which allows tossing the model with the other. very helpful when grass is your only runway.

enter "ergo-tx", a complete, low cost, easy to build, single stick radio based on a nunchuck and open source firmware. in fact everything can be done using off-the-shelf chips and parts with no need to get involved with mcu programming or any of that other stuff true geeks so love. one of the first versions i built used an m128 harvested from $9 hobbyking 9xr replacement board and pcbs from $15 flysky plug-in rf module. no flashing or mcu coding required.

however there are plenty of open source projects floating around if thats your thing. for example the popular er9x open source firmware is available which makes for just about the cheapest and most versatile ppm encoder possible as seen in my "core9x" project:

http://www.rcgroups.com/forums/showthread.php?t=1631369

for arduino fans patolin created an excellent rf encoder thread (http://www.rcgroups.com/forums/showthread.php?t=1817699) and midelics rf module project is very popular (http://www.rcgroups.com/forums/showthread.php?t=1921870). besides my core9x version ive successfully tested both of these with the ergo-tx hardware which is shown in the photo below.



attached is a circuit diagram showing how to connect the core9x or any of these modules to the nunchuck joystick. there are two possibilities for throttle control: use the built-in buttons or add a small trimpot on the side. ive tried both and must admit that for me the buttons worked best for controlling a plane. quite a surprise for someone who was brought up wiggling sticks. buttons can be implemented in a couple of ways: a simple capacitor circuit to bump adc input up/down or via software when connected directly to an mcu. the latter allows some pretty fancy throttle control features like setting upper/lower/mid levels, rates, limits, kill, etc using different button down times. ive implemented this on my tiny24 based encoder and as mentioned find it more ergonomic than a stick.

i also tried using the accelerometer chip in the original nunchuck circuit like fmkit does but for some reason didnt like it as much. somehow twisting and turning my wrist didnt feel that intuitive. maybe i need more practice.

the drawing below is not just a block diagram but actually a complete schematic with all components shown. if theres interest i can provide more links, photos, and info on things like component values and construction details. let me know. and if anybody else does actually build one of these this is a great place to show off your creation. i would love to hear about other ideas people have for low cost single stick transmitters too.
Clearly you don't the schema provided for your chunk that you have in the photo. Unless you are using 2 CPU instead of one ... that make not much sense.

I see a cheap A7105 with PCB integrated antenna.

What type of range you get from this cheap A7105 module ?
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Old Jan 08, 2014, 12:59 PM
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Yes there are 2 cpu One M8 is hidden humping XL7105..like a bug.I like that word.Lol!
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Old Jan 08, 2014, 01:16 PM
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Dave,
I see you broke the socket of one screw and the other you fixed the board with the other screw.
How you keep all together in one piece?
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Old Jan 08, 2014, 01:18 PM
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New York
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Originally Posted by midelic View Post
Nice,
which values for r1 and r2?Yes I'm more interested with details as theres are not many threads with single stick nunchuk.
yeah.. i think 4 threads including fmkit but nobody does it SIMPLE or CHEEEEEP.

resistor values depend on how responsive you want throttle to be. for my big foamies slow response is best so i use big values. it helps compensate for my tendency to over correct. i think 1k was what i started out with but dont remember what cap i used then or whats in there now. trimpots at one point but once the ohms were figured out replaced with fixed. experiment.

of course that relates to capacitor value too which is pretty important to prevent "droop". not so much adc input impedance which is pretty high but internal leakage. this is really a sample-and-hold circuit.

btw if electrolytics sit around unused for few months it may be necessary to "form" them by applying voltage for a short time. then they are good for few more months or a year. some are better than others and theres a tradeoff between size vs voltage. not much room behind those push buttons.
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Old Jan 08, 2014, 01:24 PM
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Originally Posted by midelic View Post
Dave,
I see you broke the socket of one screw and the other you fixed the board with the other screw. How you keep all together in one piece?
actually not broke but the middle temporarily screwed down for pics and working on wiring. things packed in so tight w/o that screw or top cover in place everything explodes. i did have to chop out the screw holder on the back end to make room for a lithium ion cell (make sure you use one with built-in protection ckt). much easier to pop in and out than it looks.

anyway the two case parts snap together and dont really need any screws. i do use the middle one though just to play it safe.
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Old Jan 08, 2014, 01:27 PM
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Originally Posted by midelic View Post
Yes there are 2 cpu One M8 is hidden humping XL7105..like a bug.I like that word.Lol!
What a waste

All could be done with a single arduino mini for 2.8$ shipped

Also I don't get the reason for use a cap for a digital switch ... sound a old school electronic or a lazy programmer

What is the range with these cheap A7105 module as TX ?

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Old Jan 08, 2014, 01:34 PM
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1200mAh is not overkill? A7105 is around 20mA and M328 max 300mA
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Old Jan 08, 2014, 01:35 PM
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Hey don't jump on me is not my doing .He used combined 2 separate modules patolin Tx and my FlyskyRf module .However I'm curious to see how all this is working.

Quote:
Originally Posted by e_lm_70 View Post
What a waste

All could be done with a single arduino mini for 2.8$ shipped

Also I don't get the reason for use a cap for a digital switch ... sound a old school electronic or a lazy programmer

What is the range with these cheap A7105 module as TX ?

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Old Jan 08, 2014, 01:39 PM
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Originally Posted by e_lm_70 View Post
Clearly you don't the schema provided for your chunk that you have in the photo. Unless you are using 2 CPU instead of one ... that make not much sense.

I see a cheap A7105 with PCB integrated antenna.

What type of range you get from this cheap A7105 module ?
thats a suntek which has pretty crummy antenna so range was only a few meters. enough for testing and indoor micro planes. since that pic was taken i replaced it with one like in my v911 increased range thread:



around 10x more range, maybe 300-400'. more than enough for the local soccer field. i also got a nunchuck with cheapo flysky rf module tested to 2km.

as far as 2 boards, midelic was right. heres an example of the deadbug technique from my original flsky rx thread (http://www.rcgroups.com/forums/showt...3#post23679201). instead of tiny13 ppm rx shown there i used one of midelics mega8 and instead of dealextreme type 7105 i used suntek module. no room for the big one.

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Old Jan 08, 2014, 01:40 PM
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Hey don't jump on me is not my doing .He used 2 separate modules.However I'm curious to see how all this is working.
For sure it is working

I'm just curious to know TX range

Ok I could even do on my own ... just too lazy ...

My stick with zeemote is on hold since ages ... winter time also does not speed me up

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Old Jan 08, 2014, 01:48 PM
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Originally Posted by dave1993 View Post
thats a suntek which has pretty crummy antenna so range was only a few meters. enough for testing and indoor micro planes. since that pic was taken i replaced it with one like in my v911 increased range thread:



around 10x more range, maybe 300-400'. more than enough for the local soccer field. i also got a nunchuck with cheapo flysky rf module tested to 2km.

as far as 2 boards, midelic was right. heres an example of the deadbug technique from my original flsky rs thread (http://www.rcgroups.com/forums/showt...3#post23679201). instead of tiny13 ppm rx shown there i used one of midelics mega8 and instead of dealextreme type 7105 i used suntek module. no room for the big one.

Good job, as usual

I have a couple of FlySky TX with PPM in from some cheap rtf bird, a 4ch and a 6ch tx both having same module on it

I also may use some standard TX moduke ... but design may sucks a bit with TX module hangong in the arm ...

The good 7105 module cost over 10$ ... so ... but it should fit inside

Anyhow ... if I win again my lazy mode, once I get my china numchunk I can experiment .. my zeemote case was too small for hold anything more then 328 and 6050 ...

Still I'm convinced the capacitor for have analogue thottle is not the best approach ... better use digital signal from 328 ... checking 50 time a second ... it wilk be super smooth anyhow ...

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Old Jan 08, 2014, 01:49 PM
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thanks.

btw midelic probably meant to say 3ma not 300ma. and i get a lot less current for the 7105. at least 100 hours per charge. that translates to weeks of use in the summer, months in the winter.

but you are right about lazy programmer=2 boards. in fact thanks to guys like you probably wont be publishing code on rcg anymore. hex OR source. unless already promised that is. as mentioned i got "people" for that. lol!

you are also right about digital push buttons. at least as described in post #1 there is more potential for extended features. however for those with "micro-phobia" (fear of flashing) and guys like me who always take the easy way out theres the resistor/cap approach.
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Old Jan 08, 2014, 01:55 PM
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Originally Posted by e_lm_70 View Post
The good 7105 module cost over 10$ ... so ... but it should fit inside
yeah... right... i can tell your nunchuck has not arrived yet. like i said even the the dealextreme 7105 module dont fit.
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