Zwo compatible efw

[powerlord]

Now I have asiairpro, and steadily moving down the automated ap path, a filter wheel might be on the cards soon. A manual wheel from svbony is 40 quid. But an efw from zwo is 175 quid. Seems to me a lot for a servo/stepper.

I was thinking of getting the svbony one and automating it. And since zwo have an sdk, I Decompiled that and it seems easy enough to replicate the protocol and make my one pretend to be a zwo efw.

Anyone had a go of this before?

 

[CraigT82]

Sounds like a plan. It's not just the motor though, you need a sensor to detect the exact position of the wheel and make the filters stop at the same position every time, else you will have issues with flats not correcting properly (ZWO efws are known for this issue)

[powerlord]

Not with a stepper or servo. Basic motor yeh. But some sort of alignment thing could be added I suppose if required. Possibly as simple as a hole at each position and an led/receiver?

[CraigT82]

Yeah that is how the ZWO ones work at least, there are holes in the carousel and an IR sensor. I think the more expensive brands use mechancal indexing to positon the carousel accurately.

[powerlord]

Hi chaps, just a headsup that I am now working on this.

If anyone has experience implementing usb in ESP32S2s I'd appreciate some help as the docs are pretty rubbish.

stu

[powerlord]

Dunno if anyone is actually interested in this project - but I'll keep updating for now.

So, as expected the software part has been trickiest - reverse engineering the usb interface and protocol and then trying to mimic it has been a struggle.

however, I am making progress. I now have code on my ESP32s2 board that is mimicking an EFW well enough that an asiair think it is one when I plug it in. It's sending me data and I'm sending back some fake stuff just now.

Next is to setup the right code to read the bytes I need to tell me it wants to move to a position, and to send back the position and num of slots.

Once that works, the hard stuff should be over.

then it will be building the hardware and electronics and the electronics interfaces with the esp32 - which is fairly straight forward.

I've got hold of a basic chinese 5 position 2" filter wheel for 50 quid and will be basically motorising that. I'll probably use a hall sensor to ensure its position stays synchronised.

I will say, I'm doing this primarily just as a fun and challenging project and have no plans to share the code or project - at the end of the day I have a house full of ZWO stuff, so I don't feel bad doing them out of 300 quid - they've got enough of my money.

stu

[rotatux]

12 minutes ago, powerlord said:

I'll probably use a hall sensor to ensure its position stays synchronised.

Gives me another idea. ESP32 has touch sensors. You could also use capacitive pads to check alignment : I mean, 2 facing conductive pads, one on each side of the rotating parts, and the touch would trigger when the pads are aligned enough (only one side needs to be connected to a pin).

[powerlord]

I'll have a look at that, but with the whole filter wheel being aluminium a hall sensor might work better.

Anyhoo, reverse engineering and mimicking complete.

 

Edited November 30, 2022 by powerlord

[powerlord]

nearly done - all HW, 3d printed parts, electronics and software to control it all done.

 

[powerlord]

Dada and its done!

Now to make a second one so each of my mounts has one.

 

[powerlord]

Just an update that it was tested in anger for the first time last night.

I used it with one filter (L-ultimate), so I could shoot NB data, then flip to an empty position and shoot RGB data. That way, I shot flame and tadpoles in both NB and RGB, and shot some M42 in RGB. All from my bed.

So pretty chuffed it all worked without a single hitch - my asiair flipping between the positions as required by the plan I put together.

When my duo sii/oiii 6nm filter arrives, that can be added, allowing me to do full HSO/RGB with my OSC 2600s.

So now one is working, I have another manual EFW arrived from aliexpress and will just put together a second one - really easy now all the hard work has been done.

So 2 compatible EFWs for a total cost of about 110 quid vs 650 odd. not bad even if I say so myself 🙂

stu

[adyj1]

Excellent job @powerlord!

Are you planning to share your build list and code? I have the 5 x 1.25" SVbony FW and similar plans for DIY automation, but the projects I've seen online so far have been much more complicated.

I appreciate a detailed 'follow-along' Youtube guide is quite an undertaking but if you can throw me some crumbs I'd appreciate it 😉 

Thanks

Ady

[powerlord]

I don't mind sharing hw build. Or electronics.

But I don't think it would be right to share code - it's one thing me making a few zwo compatible filter wheels for myself - it's quite another if I make how ive done it public I think? I mean, I've done nothing wrong - reverse engineering is as old as engineering, but still once its public its a few steps before some (other) Chinese manufacturer uses it to make a commercial filter wheel compatible with zwo, and I don't think I want to be responsible for that.

But, hw and electronics, I will share. If all you want to do is automate it via a Web interface ir something, or if you want to make an ascom driver, that should get you going I think?

[vlaiv]

7 minutes ago, powerlord said:

I don't mind sharing hw build.

I just wonder what is your experience with following:

- light leak

- position repeatability

I guess that manual filter wheel one starts with won't be top notch in that regard and I wonder how did you handle these two?

[skybadger]

4 hours ago, adyj1 said:

Excellent job @powerlord!

Are you planning to share your build list and code? I have the 5 x 1.25" SVbony FW and similar plans for DIY automation, but the projects I've seen online so far have been much more complicated.

I appreciate a detailed 'follow-along' Youtube guide is quite an undertaking but if you can throw me some crumbs I'd appreciate it 😉 

Thanks

Ady

Full your boots with my alpaca driver at github/Skybadger/filterwheel which is Arduino compliant but written for esp8266. Or lookup rob browns code for filterwheels and focusers also in github. You should find something there to do the job. 

[adyj1]

54 minutes ago, powerlord said:

But I don't think it would be right to share code

Ah, good point - didn't think of that and fully understand. The rest will be crumbs enough 😁 

11 minutes ago, skybadger said:

Full your boots with my alpaca driver at github/Skybadger/filterwheel which is Arduino compliant but written for esp8266.

Sounds like a plan. Thanks 👍 

Ady

[powerlord]

1 hour ago, vlaiv said:

I just wonder what is your experience with following:

- light leak

- position repeatability

I guess that manual filter wheel one starts with won't be top notch in that regard and I wonder how did you handle these two?

seems like no light leakage - basically its all incased in my 3d printed cover really - and the original manual one is all metal and pretty solid - only place light could get in is the open bit for you to move wheel, and that's where my mechanism and cover is - which fitstight all the way around it.

position repeatability is perfect really - as in video. It 'syncs' on switch on to position 1, and every time it passes position 1, so it's never more than a few filter movements away from another sync, and it can go all the way around either way and not be out anyway, but if it is, my code and hall sensor sorts it.