ATtiny85 Galloping Ghost decoder

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Wayne_H
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Re: ATtiny85 Galloping Ghost decoder

Post by Wayne_H »

Martin you've been busy :!: It looks great.

I'll probably make my first with headers for use on the bench to experiment with motors/actuators. Once happy with a particular combo, I'd hard wire it, put it in heat shrink & stick it into a model.

If a revision to the sketch needed uploading, I'd prefer to use an adapter board assembled on vero as Phil has done or wedge the header in place temporarily. 3rd & least preferred option would be soldered 90deg pins for the programming header.

Thanks again for your efforts ;)
Cheers,

Wayne
Once a Retrobate, always a Retrobate............ ;)
Tobe
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Joined: 16 Feb 2018, 06:19
Location: Varberg or Stockholm, Sweden

Re: ATtiny85 Galloping Ghost decoder

Post by Tobe »

Martin, first of all I would like to thank you for your amazing work in this matter. I have a suggestion here if you could split it in 2 different topics so whom is looking for the the simple DIY would recognize himself, find the right info and post his remarks/question in the right thread.
Cheers,

Tobe
Martin
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Re: ATtiny85 Galloping Ghost decoder

Post by Martin »

Okay Tobe, I'll start a separate thread for the simple DIY version.

Here's what the board will look like without any headers fitted. Board size is 35mm x 15mm.

Front.png
Front of board: click for bigger view.

Back.png
Back of board: click for bigger view.

I'll get the gerber files done. I'll give it a day or two in case anyone spots any mistakes or has suggestions for improvements. Then I'll get the first batch of test PCBs ordered. I think I'll be able to assemble these surface mount components okay using the hot plate or toaster oven method. Like I said, I would have liked to use the smaller DRV8838 chip, but I think soldering that would be beyond my skill level! :shock:
Martin
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Re: ATtiny85 Galloping Ghost decoder

Post by Martin »

PCBs arrived now. I've built up and tested the first four. All working as expected. I'll get some photos and maybe video over the next few days.

I ordered 100 PCBs and enough chips and other parts to finish the first 40. Once I've built some more of the batch and tested them out, I'll put them up for sale on Ebay.
Martin
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Re: ATtiny85 Galloping Ghost decoder

Post by Martin »

Boards are tested and available, if anyone wants one. A couple of videos below show the board in action both with a motorized Galloping Ghost style actuator, and a magnetic actuator. If you wish to use the third auxiliary (drive power) channel, it works as described, but if you leave it disconnected, I've defaulted the setting close to 100% now - that makes the board more compatible with Tobe and Phil's decoders which always run at 100%.





The specification is motor/actuator drive voltage from 2 volts up to 15 volts. The current rating is up to 3 amps continuous, 6 amps peak - it would probably be advisable to fit a heat sink to the H-bridge chip if you're intending to push it up to the higher currents, but when working at one amp it doesn't even get warm.

The logic circuits operate at 5V nominal (normal receiver voltage). There is no regulator on board so if you use a (rare) radio receiver running at 6.5V or more, you need a separate logic level converter to avoid damaging the board.

I'm thinking of selling them on Ebay for about ten UK pounds each with free post and packing. I think most people will want them with the right-angle headers fitted, as shown in the videos, but covered in clear heat shrink and without the programming header soldered in place. An option would be to omit the header for people who wish to solder direct to the board to save the weight/bulk of connectors: for that option I could still supply a length of clear heat shrink, but leave it unshrunk so that the buyer could shrink it over the connection pads after soldering, or leave it off entirely.

If you're interested, please let me know in this thread or by PM. This thread might be best so potential users can discuss what should be the default standard configuration. I can then start a separate thread with just the documentation and without all the clutter once they're up for sale.
Spike S
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Joined: 16 Feb 2018, 14:59
Location: Salisbury UK

Re: ATtiny85 Galloping Ghost decoder

Post by Spike S »

Very neat Martin and the video is very clear.
"... right-angle headers fitted, as shown in the videos, but covered in clear heat shrink and without the programming header soldered in place"
That configuration suits me !
Compared to the mass of original GG gear, weight and bulk of your recoder are pretty irrelevant for all except the smallest models.
Spike S
(Tune for maximum smoke)
Martin
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Location: Warwickshire

Re: ATtiny85 Galloping Ghost decoder

Post by Martin »

I designed this board using the excellent and free KiCad software then got the boards made by JLCPCB.

I'm assembling them using the solder paste and hotplate method. I've made twenty-two so far with a 100% yield though some of them needed a little clean-up work with the soldering iron. A few guys have already bought most of those. Once I get the full documentation finished, I'll make another batch and put them up for sale on Ebay.

My boards, of course, don't use the Digispark bootloader. They have the normal 6-pin ICSP header pads on board (same as an Arduino Nano or Uno). I don't fit the header connector (except to my original test board) and just hold in a loose 6-pin header pushed into a programmer (USBASP) to set the chip speed and upload the sketch.
Last edited by Martin on 14 Mar 2019, 15:36, edited 1 time in total.
Martin
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Re: ATtiny85 Galloping Ghost decoder

Post by Martin »

I've added a manual, in pdf form, to the opening post of this thread. The image below is probably the only thing from the manual that most Mode Zero readers will need.

circuit.jpg
Click for larger version.
Twitcher
Posts: 53
Joined: 16 Feb 2018, 12:17

Re: ATtiny85 Galloping Ghost decoder

Post by Twitcher »

I've been out flying this morning, trying out one of Martin's new ATtiny85 recoders. Perfect - a complete anti-climax! The only thing I noted was that for some reason I haven't yet investigated, the rudder and elevator neutral positions were some way off those set up with Phil's recoder. Not a problem - I'll give the whole set-up a good scrute (is that a word?) to see if it needs tweaking.

Excellent work Martin! I particularly like the AUX channel switch-off facility, although for numptys like me, there is a distinct possibility that I'll forget I'm not flying modern propo and try to take off with the GG actuator not working . . .

The solution might be a mix from AUX to the throttle channel, so the two work in tandem. Will that work? Answers on a postcard, please.

Don't you just love these new toys? :D

David
Spike S
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Location: Salisbury UK

Re: ATtiny85 Galloping Ghost decoder

Post by Spike S »

Twitcher wrote: 27 Mar 2019, 12:57 ... there is a distinct possibility that I'll forget I'm not flying modern propo and try to take off with the GG actuator not working . . .
David
That will never happen David because you religiously do your SMART Checks before every takeoff, checking Full & Free movement and in the correct sense :?:
However (comma) there are some risks in having such a control on a switch that can be inadvertently knocked during flight. If control suddenly ceases, would going to (and finding) that switch be possible when watching the wayward model and probably waving the Tx over your head in true Retro style ??.

There is a glaring Murphy there and I can't imagine a need to vary the AUX settings during flight so, unless the Tx switch has the chosen pulse-length at all switch settings, Martin's trimpot pulser input starts to look more attractive from the Flight Safety aspects.
Spike S
(Tune for maximum smoke)
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