Building an ascom controlled motorfocus – the minimalistic way
The internet is full of very elegant and extensive solutions for ascom controlled DIY motor focus projects one even fancier than the other featuring temperature control, IR remote control, rotary encoders, bluetooth, leds & display implementations and whatever.
My issue with all of this is that I have zero electric design experience, do not know how to read layout/electric schematics and extensive electric manuals are a mystery to me.
Problem is I still wanted an ascom controlled motor focus.
So I started looking for an absolute minimal and most simple design project for an asom controlled motor focusser.
This is what I came up with.
It consists of only 3 parts.
A motor, a motor driver board and an Arduino Nano clone.
No fancy stuff, just the minimum amount of components needed to get everything working.
Total cost: under € 30.
This project shows both electric (minimal) components needed for the motorfocus to operate. These are all listed at the bottom of the page. Besides these components also some wiring is needed and I used an old 12V power supply which I had lying around to power the whole unit.
- Small screwdriver
Electrical components needed:
- Arduino Nano
- L298N motor driver
- Nema 17 stepper motor
- 12V power supply or 9V battery
- some wiring or jumpercables
More on this at the bottom of the page.
Besides the electrical components also software is used to which is loaded to the Arduino microcomputer and installed on the PC which allows astrophotography/automation programs to directly communicate with the focusser and adjust focus whenever needed. All this software is available free of charge and mostly already pre-written for the motor driver which is going to be used. There are several options here, but I went with the L298N driver.
Below is a step by step guide how to assemble the electric components and install the required software to get things going.
To get things operational from a software point of view you need to have the Ascom platform installed on the computer operating the focusser, and you need an ascom driver for programs such as Maxim DL, CCDSoft or Sequence Generator Pro to communicate to and operate the focusser on the same computer.
Besides the Ascom platform and driver you also need specific software to run on the Arduino that through the motordriver operates the motor. This software is however already written and available from Sourceforge. More on this at the bottom of this page !
In order to get the focusser operational you need Arduino software which is used to modify the code (if needed) and upload the (pre-programmed) code to the Aruino microcomputer.
Thats is all.
I am aware that below summary in pictures is a bit brief and will try to update to a more extensive overview.
It basically comes down to removing the 10:1 reduction form the Moonlite using the small allen screws in the focusser knob. Then using either timing/drive belts and aluminium pulleys to the axis of the motor and the Moonlite or a direct axis coupling by using a 5mm Z-axis coupler. All of these items can be easily bought from online retailers. Also see the parts listing at the end of the page.
1) First you need a Nema 17 stepper motor. Just use google. This motor is normally used in 3D printers and should be readily available.
You can find small differences in holding torque, steps per revolution and some come with planetary drive (at a much higher price).
Price level somewhere around $16 or about €14, although you can get these cheaper from AliExpress.
You can buy these from Amazon, AliExpress or other online electronics shops and retailers.
2) The second component you need is the L298N motor driver, just google this as well as the same also applies for this driver.
You can pratically buy it anywhere. Pricing around 3 to 5 euros or usd.
3) Last component is an Arduino Nano. It is up to you if you buy the original version or a Chinese clone. I bought the latter and it is operating without any problems whatsoever. A quick search on Google will show you where to buy them. Price is around €5 or about $6 to $7 (for the Chinese clone)
Besides these main components 2 additional items are needed which is wires or jumpercables to connect the components (no soldering needed) and a surplus 12V power supply or 9V battery to power the (stand alone) unit.
All required software is free of charge:
ASCOM Platform > Start with downloading and installing the ASCOM platform
Arduino.cc > Download and install the Arduino software next. This is needed to program or change the code for the Arduino Nano and upload it to the Nano.
Sourceforge – project page > The main project page on Sourceforge.
Sourceforge – files folder > Download the software for the Arduino. Look in the folder “DRIVER BOARDS”. Pick the L298N and download the (M)inimal version.
Sourceforge – files folder > Look in the folder “CODE ASCOM” and download the myFocuserASCOMSetup16xx.exe file. When this is installed, it allows programs such as Sequence Generator Pro or Maxim DL to communicate to the focusser.
These are the minimum software requirements to get everything running. You could optionally also download the test code to check in windows if and how the focusser is moving before installing everything to the focusser on the telescope.