DIY Stepper Motor Controller Question

[vignesh1230]

Okay. This might be a stupid question but, how does a stepper motor controller (the computerised kind that works with software like Starry night)? Does the microcontroller itself have the ASCOM protocol or does the controller recieve data via serial after being through the ASCOM thing. Im very confused as i have found 2 perfect stepper motors that fit perfectly on my telescope and would like to make it computerised.

[tlgerdes]

You write an app that accepts ASCOM langauge and converts it to Stepper motor language. Then any ASCOM compliant app can drive your stepper motors.

[vignesh1230]

So if i wanted to use Starry Night, id need the ASCOM driver to be installed, then it will automatically output into the needed input for the controller?

[Barrykgerdes]

You will need more than software to interface bare steppers to a mount and a control program. You will need to buy or build a "black box"

Look at the Mel Bartel's system. It works well and there are drivers for it available. All you need is the kit of parts and some electronics experience to put it together.

There is at least one commercial device I know of "Synscan" and it will probably cost less than one you can make yourself.

Barry

[tlgerdes]

As Barry said, a little simplistic.

You will need to
1) Build a stepper motor controller that can accept some form of computer control.
2) Interface hardware to computer
3) Write an ASCOM driver to accept ASCOM control parameters and interface with your stepper motor controller.

Then you could use Starry Night to controll your stepper motors.

[alistairsam]

Hi Barry,

is this similar to the Skywatcher Synscan or Celestron Sysnscan? would you know which controller it would work with?

I'm currently building a computer to stepper controller interface using the existing LX200 ascom driver.

I'm using a picaxe microcontroller to control my stepper controller and driver, and am now working on programming the picaxe to "interpret" the LX200 serial commands from the software into relevant input pin states of the stepper controller for basic functions like slew, track speed, etc.
so i'd choose LX200 as my telescope in the software and interface my serial port to the picaxe.
same thing can be used for interfacing ST4 outputs from an autoguider to the mount.

writing a new ascom driver is a huge challenge and needs approval from ascom i think.

[Barrykgerdes]

The synscan principle is used with the celestron and Skywatchers. I imagine the controllers are similar but I don't know the details of the interface to the motors.

I imagine it is some form of microstep generation via a stepper motor controller chip. I would expect that a Picaxe controller could be made to duplicate all the functions you require.

If you make your interface respond to LX200 commands you won't even need the ASCOM interface as all the programs I know of have a LX200 connection.

Barry

[ballaratdragons]

You'll need these: http://www.jaycar.com.au/productView_test.asp?ID=AA0352&keywords=stepper&form=KEYWORD

and here is the software program to run it all: http://www.jaycar.com.au/products_uploaded/AA-0352%20Software.zip

:thumbsup:

[Barrykgerdes]

A quick look at these products says they won't be suitable for this type of project. Also modern computers don't seem to have printer ports any more and the USB - parallel adaptors only work with printers.

Barry

[ballaratdragons]

Well that's a pain in the butt!

All my computers and laptops (except one laptop) have Parallel ports and I use that particular Stepper interface for my Huge mount.

Also, there is an adaptor that is Parallel/Serial. It works with modified Toucams/900NC's for PC's with no parallel port :thumbsup:

But if Vignesh just wants the latest in equipment, well I have no further suggestions.

[alistairsam]

Ken, do you use Astro software like CDC or stellarium to control your mount for goto and tracking with this stepper controller, if so I'd be very interested to see how it works.

[Barrykgerdes]

Hi
I have built many stepper drive computer interfaces. but they have always used the computer parallel port for communication. If you want to use serial or USB you will need to build the interface in hardware as part of the controller.

Another problem with parallel port control is that most control functions are written as eight bit words by directly addressing the ports. This facility has been inhibited in the latest versions of Windows as a security vulnerable. It can be bypassed but this is a bit messy.

Barry

[alistairsam]

Hi,
were they for control with astronomy software with ascom drivers to slew and track? if so which driver did you use in the software and how did you translate outputs from the software to inputs that the stepper controller would understand and use?
the controllers from jaycar, ocean controls and several others have built in serial interface hardware and software that comes with it that can be used to drive the stepper. but the challenge would be to use that interface with astronomy software commands, especially for autoguiding.
I guess its similar to DIY CNC machines where they get standard CNC 3 axis controllers and serial interface it to the software Mach3 which works with different hardware.

[mswhin63]

The future will be to output digital signals from a simple USB interface and then code it different to mimic parallel port.