tekkydave

Dave is it possible to download the ASCOM driver project? I can't see it on the sourceforge site.

You will need to use subversion to checkout the code. You can use a client such as tortoisesvn to check out to local disk or check out the project directly in visual studio. Click on the Browse Code button on the SF summary page and it will give you the svn url to use for a read-only checkout. You can't commit any changes you make back to the site - only I can do that. If you just want to look at the code you can browse the files from this page.

Most of the bits have arrived, do stepper motors have a standard spindle size ?  I can only find 4mm or 5mm wheels but it seems to be between the two (must get a metric micrometer) 

Measures just under 20 thou inch.

Dave

The one I used from Technobots is 5mm and fitted the motor shaft after a small amount of filing with a needle file.-

hi

I decided to just get the adfruit motor shield as I didn't want to mess around with adapting the easy stepper board too much.

got the project finished. It works a treat on the bench although I had a bit of an issue on the mount as I think the USB hum system is not sufficient to drive the stepper properly. It just does not seem to have enough torque to drive the belt to the Canon 200mm lens. I think I will add a 12v supply to the motor shield board. It's a excellent project and will really help in the critical focusing of this lens

Nice work. I'll have to go back through the thread and count how many people have built it. Must be 4 or 5 by now plus me of course.

Positioned the scope to point at the zenith, attached the camera, OGA, guide cam, reducer and set it to retract. Everything worked!

Thanks again Dave for this great bit of DIY!

Thanks. Glad you got it all working.

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.

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.

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

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.

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.

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

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

Hey! What are you saying

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.

I don't know about ascom-based programs but I used an Arduino Nano to control cooling for a cold finger cooled 1100D DSLR a while back with an LCD display running off digital I/O lines and using a DHT22 to read temperature and humidity near the image sensor to display dew point.  Cold finger temperature was read with a DS18B20.  The serial I/O was assigned to computer readout.

BTW - you can use 1-wire to control the stepper motor.  I am doing that for my multiple CCTV project for pan & tilt control though I haven't written the Arduino sketch that controls the whole system yet.  It's yet another project in progress

Thanks Gina, I am following your 1-wire CCTV project with interest. I already have the focuser working quite happily just using the nano and stepper driver. I want to 'K-I-S-S' and stick to the design I already have, just adding the temperature sensor. No extra hardware or software will be involved apart from the DS18B20 i.c. and a few simple mods to the sketch and driver code.

It's not ASCOM, but APT reports humidity but that normally requires a separate sensor.

The bracket was made with nothing more than a cordless drill and a C clamp.

Thanks - I'll have a look at how APT is doing it.

Regarding the temperature/humidity question - does anyone know of an ascom-based program that displays or uses humidity? I want to keep the focuser as a self-contained device with all communication via the ascom driver. If humidity is not useable by ascom I will restrict it to temperature only. I have some DS18B20s ics already from previous 1-wire projects so I can have a go with those.

While I'm waiting on the rest of the parts to arrive, I thought I'd give making the bracket a go. Turned out OK, just hope it's well aligned!

That looks very professional - puts my cork mats to shame

Thanks Dave,

Is it obvious what the lines in your prog' do or is it annotated, used to do endless annotating as my memory wasn't that good and it's a lot worse now

Dave

I think you will find them well annotated. I always do lots of comments. Programs are for people to read not computers

My memory is getting worse these days and it makes life easier if you need to go back to a program after a period of time.

The arduino sketch is written by me so I have had free-rein to structure and write it how I like. The ascom driver uses a template provided by ascom and has fixed methods and properties so cannot easily be customized. I have moved any custom code, wherever possible into a separate class called AAF2. This makes it easier to maintain and also simpler to re-implement if the ascom template is changed in the future.

Thanks Dave, will order bits.

By the way what is the programming language like ? haven't programmed since Delphi 2 and Win 98 and a bit of Access 2003

Dave

The Arduino is programmed in a simplified version of C/C++ which is easy to pick up. There is a java-based ide on the arduino web-site which lets you write the programs (called sketches) and upload them to the arduino. The Ascom driver is written in C# which is a bit more complex but has many elements in common with C and Java. To write these you will need the Visual Studio ide. There is a cut-down free version you can download.

If you are building my focuser and using the arduino sketch and driver on the sourceforge site you won't need to do any programming unless you want to modify the way it works.

Now you've inspired me Dave,(and done all the hard graft)  I'm going to have a stab at making a focuser for my Lunt LS60.

You appear to be using a 9v stepper motor but I can only find 5v and 12v on EBay.

Is this suitable ?

Dave

http://www.ebay.co.uk/itm/New-5V-Stepper-Motor-With-ULN2003-Board-5-Line-cable-for-Arduino-Raspberry-Pi-/131070819595?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item1e846dfd0b

That board is the same one I used. It will work fine connected directly to the Arduino with no extra external power supply. The torque is not so high like that so adding adding an external supply on the pins marked 5-12V will give it a bit of a boost. I used 9V as it was convenient to use a PP3 battery in the focuser box.

Good luck with the build and feel free to fire any questions at me if you get stuck.

I just read the sensor directly, calculate the dew point, and report it on an LCD that I've attached; that will be located in my warn room.

I don't really want to connect an LCD to the focuser. The nano's serial connection is fully occupied by the Ascom driver so another program would not be able to access it without disconnecting the client program first then reconnecting again to use the focuser.

Looking at the Ascom spec there isn't a standard method or property for humidity, just temperature. There is the CommandString method that could be used to access the humidity from the Arduino.

Sounds good. Also, I knew nothing about arduino programming but was able to get a TEC cooler program up and running quite quickly, the arduino site is very helpful.

The common temp sensor is the DS18B20 and there's a good example on the arduino website:

http://playground.arduino.cc/Learning/OneWire

Also, the DHT22 is a good, cheap temperature and humidity sensor that works well with arduino. Though you might have to get the humidity outside of the focuser driver?

Just did a bit of research and there is a 1-wire arduino library ready to use. It doesn't need any extra electronics such as a 1-wire adapter or bridge chip which is usual in other applications. It works by so-called 'bit-banging' on an i/o port so will work for a limited number of sensors. As we only need one that's not an issue. In terms of humidity - is that something that would be useful for a focuser? If so I could look at the DHT22 as an alternative approach.

Would it be much extra work to include temperature monitoring? I know it's pretty straight forward, and cheap, to add a sensor to the arduino. I'm just not sure about the ASCOM driver side of things!

It ought to be fairly simple. I use 1-wire sensors for my weather station but I've never used them with Arduinos. I know Gina has so I'll have to look through some of her posts. From the Ascom side it will be simple to modify the Arduino sketch to add an extra interface command to read the temperature. The Ascom driver already has the correct methods built in as it is part of the focuser class already.

I'll look into it

Gone are the days of the local ironmongers unfortunately, where you could buy nails by the pound, in eco friendly paper bags!

Rob

When I was a kid I used to buy nails by the quarter from our local hardware shop. Not because I needed them - I just liked the ritual and the smell of the shop and the nails. Maybe I'm just weird

excellent project. I have just got a 200mm lens and I was going to try and build this focuser. Parts ordered to try the drive belt approach. I already have an arduino. I ordered an easy driver board so hopefully I will be able to use this with the arduino

Thanks for considering my project. I think the easydriver uses direction and step pin connections rather than the 4 separate lines my design uses. You will need to amend the clockwise() and anticlockwise() functions in my sketch to work correctly. It might be best to search out a sketch that uses the easydriver and 'borrow' the appropriate sections. If you get it working let me have a copy and I'll add it to the sourceforge project.