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SimpleGpUsb - A home brew auto guider...


samtheeagle

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Hey all, I've finally finished writing up my home brew auto guiding project, so if you're in the slightest bit interested here it is!

http://www.guywebb.co.uk/SimpleGpUsb/SimpleGpUsb.pdf

http://www.guywebb.co.uk/SimpleGpUsb/SimpleGpUsb Files.zip

I hope that I've got all of the required files together, and the words make sense to you... All comments and feedback welcome.

Now all I need is clear sky so that I can use it again! :icon_salut:

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Cheers Peter :icon_salut:

I know that there probably wont be all that many people clamouring for this, but as I've put in a fair chunk of hours working on this it seemed a waste to keep it all to myself. And having got so much out of this forum I really wanted to try and give something back...

If anyone has any questions, just fire away here.

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It is good of you to post it up for others Sam. I recently sold my EQ5 Mount that could have benefitted from your project.

I hope others at least explore the possibilities regarding their own setups. Autoguiding can make so much difference to an imaging beginner with modest equipment.

Thanks very much for posting it up.

Ron.:icon_salut:

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You're right about the difference made Ron. I was so amazed at the wonderful tight little circlular stars I got out of a 5 minute exposure! :icon_salut: Unguided I had trouble getting anything over 30 seconds without trails. I really don't know how people get 2 minutes unguided, fair play to them!

I'm getting a nasty itch to fiddle with my guider atm :S I should really just leave it well alone, as it works fantastically already, but I think I might have a discrepency with the guiding rates... Maybe someone can help me out? I shall try to explain as best I can...

The "instructions", such as they are, that the EQ3-2 motors / hand controller have refer to speeds of 2x, 4x and 8x but only talks about the right ascension axis... I have assumed that the same speeds are applied to the Declination axis? Now tricky part is that the ASCOM driver I have written defines guiding rates as an offset from the normal tracking speed, so the actual rates should be 1x, 3x and 7x from the driver perspective. Now the Dec axis does not track, so will the speed be the full 2x, 4x and 8x, or will it just cheat and use the same tracking adjusted rates?

Anyone got a cunning plan on how I can determine the actual speeds put out by the two motors at different hand controller settings?

Like I said, it currently works very nicely, and I should leave it well alone, but I hate having these niggles festering in the back of my mind.

G.

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I've got an EQ3-2 that I probably won't be swapping for anything better for a while, so I may just have to give this a go sometime in the future. I think the only off putting for me is that I'll probably have to mod my webcam. Its a few years since I really used a soldering iron on an electronic circuit. I reckon that I'd break something at the moment.

gareth

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@gman - I initially had trouble getting PHD to control the long exposure of my toucam, but still it was sensitive enough to pick up guide stars! That was at 5 fps for the longest standard exposure time, and only through the small 50mm finder scope that I use as a guide scope. So you might not need to mod it immediately, assuming that the webcam is for guiding and not imaging that is :icon_salut: I totally bailed on the LX mod front and purchased one ready made! I understand your reluctance to hack away... The soldering required for the guiding device really is very simple in comparison.

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Hey all, I've finally finished writing up my home brew auto guiding project, so if you're in the slightest bit interested here it is!

http://www.guywebb.co.uk/SimpleGpUsb/SimpleGpUsb.pdf

http://www.guywebb.co.uk/SimpleGpUsb/SimpleGpUsb Files.zip

I hope that I've got all of the required files together, and the words make sense to you... All comments and feedback welcome.

Now all I need is clear sky so that I can use it again! :)

Hi, interesting project and it is just what I am looking for simply to remote control the R.A and Dec drives from a distance. I was looking at another project by Erlend Rønnekleivs to do this but this one seems less "fuss". I do have one question, after reading through your pdf file. Is there no common GND from the CP2103 USB to Serial Board, to the ULN2003A?

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No, there isn't. That confused me for a good while there, being electronically challenged, but it works perfectly with the 4 GPIO pins connected directly the the ULN2003A inputs. There is a GND pin on the CP2103, but I didn't need to use it. You should be able to see from the internals image in the pdf that the only GND wire is the one from the RJ-12 socket.

Best of luck :)

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Having just had a very quick scan of the web page you referred to it seems that our two solutions are very similar, it's just that I opted for a USB interface and implemented an ASCOM software driver, which I hope will make it a little more user friendly...

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I've moved house and as its the carp season for astronomy I hadn't got the scopes out at all in over a month, next few weeks and i'll be looking into programming again, I got my arduino out of storage last week, so, I should be good to go :)

Still got a couple of things to iron out in the garden, been ripping posts out of the ground the last couple of days and getting my landlord to get the large shed more socpe friendly so i can store stuff in it, just need to alarm it properly.

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I moved closer to work, shaves a couple of hours off travelling a day, I've just changed departments at work which gets me home an extra 1/2 hour earlier on top too, just need to buy a semi-unobtrusive hi-end (quad core or i7 w/ddr3) PC for the front room and get organised :)

Of course it means I'll need to add a new monitor to that rig too cos the missus won't want me using the TV in the front room as a monitor.

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Having just had a very quick scan of the web page you referred to it seems that our two solutions are very similar, it's just that I opted for a USB interface and implemented an ASCOM software driver, which I hope will make it a little more user friendly...

Hi, thanks for the response, yes the ASCOM software driver was a plus with your idea. Basically I just wanted to be able to remotely control the EQ5's handset, nothing worse than retreating to the PC indoors to find fitting the camera has nudged the target out of the FOV. I was about to order the CP2103 when a freind of mine told me he was upgrading his mount and had a Shoestring astronomy GPUSB going spare. Got that for £25 so am about to fit it and use that instead. But now I know of the CP2103's existance I do have other ideas for a few things that will benefit from your idea.

All the best

Rod

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Sounds like you got a bargain Rod! If there was one of those on offer to me at that price I'd never have undertaken this crazy endeavour! :) Just after I'd bought all the constituent parts there was one on astrobuysell for £35 just to tempt me! Still, it was interesting and it's really quite satisfying to make something from scratch.

And yes I would think the CP2103 would be useful for a number of automation projects... Depending on the complexity you want the Arduino boards could offer you more oomph tho. Just something to consider...

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  • 9 months later...

Guy,

I am trying to talk to the GPIO ports using the Silicon labs readwrite utility. I can see the chip on the proper com port, I can program it using their programming utility, but I can't change the GPIO values with the readwrite utility. Any suggestions?

Cheers,

Pete

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Hmmmmm, that's odd. I can't say that I ever had problems with that util. So going from scratch, and relying on my feeble memory, it should be something like this:

* Attach CP2103 device to computer

* Start read/write util

* Select appropriate COM port for the device

* Tick the boxes for the GPIO pins that you want to change

* Click on the "numer squares" to toggle the pin value between 0 and 1

* Then click the write latch button

I hope that I'm not being offensively simplistic here, just figured I'd go through the steps as I remember doing them...

If you're doing all of the above I can only assume that there's some issue with the way that the CP2103 is configured. The key issue I had was the GPIO Reset Mode needs to be set to Push-Pull, without that I couldn't get the pins to go high and low correctly.

Hope that helps?

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  • 3 weeks later...

Hi - just came across your autoguiding modification which I am interested in trying. However, I have a gotonova handset which drives servo motors, but the same mod to the 'back' of the handset switches should work. Just in case you dont know the gotonova kit is advertised as having an autoguider port - but it is not implemented in their driver and other users have been lobbing the manufacturer to fix it for a couple of years now. I was just about (my wife actually for my birthday) to purchase a Syncscan kit for my EQ5 mount when I came across your work.

regards

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