Arduino Ascom focuser Mark2

[tekkydave]

Very sensible   I'm only using 1-wire stepper control to reduce and simplify the kit at each camera.  It's mainly the built-in ID code in the 1-wire devices that make the difference - I can stick them all on the same pair of wires.  No need for special selection circuitry

Thats the beauty of 1-wire - I have 8 sensors all on a single pair of wires in my weather system and it just works. It will scale to 100s and cable lengths of 100m or more with a decent adapter/bridge.

[tekkydave]

...who's designer has probably done their homework.

Hey! What are you saying

[tekkydave]

I'll try to get the temperature sensor working asap but it will have to join the queue behind my other project at the moment which is to get my pier finished. I need to get my work bench and bench drill set up (hopefully this weekend) so I can complete the plate drilling. Sadly I have to something called 'work' 5 days a week which is getting in the way. Hopefully I can retire in 3 years or so and spend more time doing sensible things like sitting in my shed in the dark

[russellhq]

I'll try to get the temperature sensor working asap but it will have to join the queue behind my other project at the moment which is to get my pier finished. I need to get my work bench and bench drill set up (hopefully this weekend) so I can complete the plate drilling. Sadly I have to something called 'work' 5 days a week which is getting in the way. Hopefully I can retire in 3 years or so and spend more time doing sensible things like sitting in my shed in the dark

Yes, work does have a bad habit of getting in the way! I was reading the ASCOM documentation and I guess you would have to set up a timer in the driver to poll the focuser for the temperature. I don't think it's possible for the focuser to notify the driver of a change in temperature.

[tekkydave]

Yes, work does have a bad habit of getting in the way! I was reading the ASCOM documentation and I guess you would have to set up a timer in the driver to poll the focuser for the temperature. I don't think it's possible for the focuser to notify the driver of a change in temperature.

Interesting. I would have expected the client program (APT etc) to request the temperature from the driver. The driver will then query the focuser and pass the temperature back to the client. I haven't looked into it yet so I might be wrong.

[russellhq]

Interesting. I would have expected the client program (APT etc) to request the temperature from the driver. The driver will then query the focuser and pass the temperature back to the client. I haven't looked into it yet so I might be wrong.

Of course, sorry I'm not very good with this programming malarkey

Temperature is one of the properties of the Focuser class, so it would make sense that the Client requests it from the driver!

[tekkydave]

Of course, sorry I'm not very good with this programming malarkey

Temperature is one of the properties of the Focuser class, so it would make sense that the Client requests it from the driver!

That makes sense. I'll have to make sure I return a sensible default from the arduino if the temperature sensor is not fitted aswell. Not everyone will want to fit one.

[Gina]

Adding ASCOM control to my focuser systems is definitely on my list but ATM I really feel I must finish some of my other projects first   I already have too many on the go and the manual remote control is working pretty well.

[russellhq]

Struggling a bit here. The parts arrived today and I got everything wired up, except I'm not using a switch.

I first tried with the 5v source from the nano, and then with a fresh 9v battery. The stepper would turn but was pretty gutless, I'd say it couldn't pull the skin off a rice pudding!

Have I got a duff stepper or am I doing something wrong?

Here's a short video of the parts:

[tekkydave]

Struggling a bit here. The parts arrived today and I got everything wired up, except I'm not using a switch.

I first tried with the 5v source from the nano, and then with a fresh 9v battery. The stepper would turn but was pretty gutless, I'd say it couldn't pull the skin off a rice pudding!

Have I got a duff stepper or am I doing something wrong?

Here's a short video of the parts:

If it is turning and responds correctly to direction commands then you probably have it all connected correctly. I found it is fairly weak just powered from the nanos 5v supply but is stronger on 9v. Without the battery it is getting its supply from the usb port which may not be up to it - it may well be different on different PCs I suppose. Does it seem to be stronger on 9v? I find with the pulley attached I can still stop it turning with my fingers but it has enough grunt to turn the focuser knob via the toothed belt. Double check all your connections - the leds on the driver board should all be off when the stepper is stopped, I can't tell from your video if they are flickering or not. Hope that helps.

PS - well done on getting it working so quickly. If you post some close ups of the connections to the nano and the driver board I can check them against mine

Edited September 17, 2014 by tekkydave

[Mick J]

I guess you have to try it and see.  I know from your other posts you are going for direct drive 1:1,  our setup is much like wuthton - 20 tooth and belt, about 3:1 (wuthton post #146).  Not much of a modification for you to adjust the bracket if you have to.

As above a bit more grunt from the motor with the additional 9volt battery.

[russellhq]

Thanks guys, I did try a 9V batter, but same issue. I notice the board states 9-12V. Maybe I could run a 12v line from my power supply, that might give it more grunt?

[Mick J]

Here's a quick snap off my phone,  9v battery box stuck to box containing motor etc.  I have changed this now as added short usb cable and made connection onside the box.

Easy to adjust belt tension using washers on the mounting.

[wuthton]

Thanks guys, I did try a 9V batter, but same issue. I notice the board states 9-12V. Maybe I could run a 12v line from my power supply, that might give it more grunt?

You may be pushing the limits of the motor with direct drive but there's no harm trying. As Mick has pointed out you get a lot of advantage from the belt/pulleys which reduces the strain on the motor.

Here's a quick snap off my phone,  9v battery box stuck to box containing motor etc.  I have changed this now as added short usb cable and made connection onside the box.

Easy to adjust belt tension using washers on the mounting.

Nice job Mick, I must tidy up my bracket.

Matt.

[russellhq]

I should have pointed out, the direct drive is connected to the 11:1 fine focus spindle, so should already be getting an advantage. I'll try with the 12v and see what happens, though I'd rather not run another cable just for the focuser.

[Gina]

That should be alright

[Mick J]

I should have pointed out, the direct drive is connected to the 11:1 fine focus spindle, so should already be getting an advantage. I'll try with the 12v and see what happens, though I'd rather not run another cable just for the focuser.

ooops,  I should have looked a little closer, 11:1  of course.

[russellhq]

If it is turning and responds correctly to direction commands then you probably have it all connected correctly. I found it is fairly weak just powered from the nanos 5v supply but is stronger on 9v. Without the battery it is getting its supply from the usb port which may not be up to it - it may well be different on different PCs I suppose. Does it seem to be stronger on 9v? I find with the pulley attached I can still stop it turning with my fingers but it has enough grunt to turn the focuser knob via the toothed belt. Double check all your connections - the leds on the driver board should all be off when the stepper is stopped, I can't tell from your video if they are flickering or not. Hope that helps.

PS - well done on getting it working so quickly. If you post some close ups of the connections to the nano and the driver board I can check them against mine

Here's a photo of the connections. I'm pretty sure it's wired up as per your schematic.

The lights flash when the motor is on low speed. When it's high, it's very hard to see them flashing. when it's stopped, they are off. The exception was when it was on separate power, in that case, when it was stopped, that lights stayed on.

I tried 12v from my 10A supply and it didn't seem to make a different to the torque. The only difference was the motor got quite hot. Had to turn it off before it got too hot to touch.

I can't see this being able to turn the focuser knob with the pulley. Think I might try buying a new one, maybe this one is knackered 

[Mick J]

I could be mistaken - but the Blue & Green cables bottom of nano in picture above,  vin & gnd are the bottom 2 pins on my board, vin being + and gnd being -

I am swapping glasses here, reading glasses, a stronger pair for looking at nano's and the one with the red wine.  Will look closer tommos with better light.

[russellhq]

Yes, you are correct. I've connected to pin 29 and 27  which are GND & 5V. I think Vin is only for supply power?

http://arduino.cc/en/uploads/Main/ArduinoNanoManual23.pdf

Edited September 17, 2014 by russellhq

[Mick J]

I don't know if this may be helpful,  circuit in black & white, motor dimensions and pin out that I cut out and placed over my board.  if I don't have something like this when I come back to it in 10 minutes/ three weeks/whatever I have forgotten what's going on, 

Focuser#2.pdf

[tekkydave]

I could be mistaken - but the Blue & Green cables bottom of nano in picture above, vin & gnd are the bottom 2 pins on my board, vin being + and gnd being -

I am swapping glasses here, reading glasses, a stronger pair for looking at nano's and the one with the red wine. Will look closer tommos with better light.

Yes, pin 30 is for Vin. Pin 27 is a 5V output from the nano. The stepper connections look good to me. Try connecting your battery or psu directly to the stepper driver board power pins only and see if it makes a difference. The nano will run quite happily on the power it gets from the usb. I only connected the battery to the nano Vin so it would stay powered if the usb power failed. Edited September 18, 2014 by tekkydave

[russellhq]

Yes, pin 30 is for Vin. Pin 27 is a 5V output from the nano. The stepper connections look good to me. Try connecting your battery or psu directly to the stepper driver board power pins only and see if it makes a difference. The nano will run quite happily on the power it gets from the usb. I only connected the battery to the nano Vin so it would stay powered if the usb power failed.

Thanks Dave. That's how I wired it up, power directly to the stepper board. I've ordered a new stepper (£4) just in case this one is faulty. If not, then I think I'll need to look at the focuser tension and then consider pulleys. For the pulley, I'm considering putting a big pulley on the fine focus shaft so I get an even greater reduction.

[tekkydave]

Thanks Dave. That's how I wired it up, power directly to the stepper board. I've ordered a new stepper (£4) just in case this one is faulty. If not, then I think I'll need to look at the focuser tension and then consider pulleys. For the pulley, I'm considering putting a big pulley on the fine focus shaft so I get an even greater reduction.

Always worth having spares

I managed to destroy the chip on the stepper board when I was first experimenting so I have a good stock of those now, and spare boards & motors - just in case.

[russellhq]

New motor and control board arrived today. It's the same make and model but is much stronger, more importantly it turns the focuser! Next test is to see if it can turn it with the camera attached!