TinyTwo Speed Controllers

[Rapidrory]

Hi guys,

So 4 months ago when I started looking into antweights, I realized that there wasn't a whole load of small 2 channel ESC's available, and those which were costed far more than I had expected. So I thought, "I know, i'll just make my own! How hard can it be?"

Well, 4 months later having spend almost 100 hours laying out boards, hundreds more sifting the internet for components, learnt PIC assembler and spent hours fighting with that, and yet more time debugging... I've decided it was very hard!

Nonetheless, last night I finally got the prototype working, and today got it working well enough to do a demo.. so that's exactly what I've done!



Video: http://www.youtube.com/watch?v=s3eNNzrk ... e=youtu.be

I didn't want to mention it until I had a working prototype, as up until yesterday I had no idea if it would work!

Here are some specs.. I haven't had the confidence yet to test the current or voltage rating yet, so those are taken from the data sheets.

Max current per channel: 3.5A
Max Voltage: 18V
Dimensions: 21mm x 21mm
Weight: 4.5g with test cables, probably about half that without.

5V supply at ~1A to RX (will be 6V at ~2A on the next version)
Channel mixing done in firmware so can be used with cheap transmitters.

It's designed to accommodate the needs of a 4 motor pusher running at unnecessarily high voltages *cough*Haywire*cough*, hence the high current and voltage ratings.

There's a few bits on the design that need tweaking for the next version, and the firmware also needs a bit more work, but it's in a more or less usable state now. I've been trying to get it ready in time for the AWS otherwise I'd have nothing to run my Ants with!

If I were to do a batch of these once the design's been finalized, would anyone be interested in buying one? Having spent so much time developing it, it would seem a bit of a waste only to make a couple for myself... And if so, any ideas for other useful features whilst it's still in development?

[Shakey]

You know I'm interested in a few for my team

[haz]

[joey_picus]

I'd definitely be interested in at least one or two would they have any compatibility issues with Corona recievers? I still have most of LYT's old electronics...

[Shakey]

It's designed to accommodate the needs of a 4 motor pusher running at unnecessarily high voltages *cough*Haywire*cough*, hence the high current and voltage ratings.

Hey I feel it is all completely necessary Especially the high powered motors and more wheels than any sane man would use!

[BeligerAnt]

Nice work Rory, although using a PIC and programming it in assembler is definitely doing things the hard way!

If the board is using two of the Toshiba motor driver chips in parallel it might not survive too long with 4 high power motors on 4S! Hopefully you've found some better driver chips.

Be aware of the issues of "placing on the market" in Europe any electronics-based product. This is why Peter Waller only makes his boards to order for friends. Offering stuff for general sale opens a whole can of approvals issues that you can't realistically comply with!

BTW I also have an open-source speed controller on the way...

[Rapidrory]

Yeah, i chose the PIC cause it was small; hadn't really factored in the firmware :L

The motor driver chips are good for 30V at ~4A; it's the CMOS logic chips that limits it, so it should be fine up to 18V :L

And yeah, i'm only planning to sell to you guys with a lot of disclaimers :L

Ooh, sounds interesting! I hope it's slightly less difficult to build than mine :L

[marto]

Impressive. Everyone seems to say I could make an ESC for cheaper, which has more amps and more features but very few actually follow through.

Again nice work. Looks good and be keen to hear how it goes with testing.

Steve

[Rapidrory]

...would they have any compatibility issues with Corona receivers?

If those receivers work with normal servos then should be fine; the ESC's only decoding the servo signals. Even if it did have a different servo signal, it should only be a case of changing 1 value in the program to calibrate it to the new signal

[peterwaller]

First of all well done, having gone through this process myself I know just how much is involved.
As Gary says you have to be careful about openly offering them for sale with all the european legislation.
One word of warning the regulator part caused me more problems than I would have expected and you need to be very careful about the spec.
For instance if you rate the controller at 18v and the 6v regulatot at 2A you will be disipating 24 watts in the regulator assuming it is a linear type.
Also at 6v on two cell lipo you will be below the drop out voltage on normal regulators as the battery voltage dips below 8v so you may need and LDO regulator.
I use the LD29150 which is a low drop out (0.4v) 1.5A 5v regulator.
Another thing I halved the number of failiures in the field by fitting the battery leads with a non reversable connector so people don't reverse the batteries so often.
The question of compatibility with the Corona receivers and some others is that they output channels simultaneously and not sequentially as with standard receivers so depending how your firmware works they can cause problems.
Any way good luck with the venture you can't have too many controllers available.