Since I acquired an Losmandy G11 mount without any goto provision I decided to create my own solution. I was a bit reluctant to use a Gemini, mainly because of the cost, but also due to the reliability since the servo motors are somewhat prone to failure. I also like to have complete control over the software/firmware so that no “show stopper” issues will ever be a problem for me. Looking around the ‘net I saw other goto systems that seemed capable, but either they had needlessly complex hardware or were commercial systems that cost about twice what they should.
OnStep is a computerized telescope control system designed to run on inexpensive Arduino micro-controllers.
It was designed, from the beginning, as a more or less general purpose system and provisions were made in the firmware to allow its use on a variety of telescope mounts including Equatorial (GEM, Fork, etc.) and Alt/Az (Dobsonian, etc.)
OnStep can control Mounts, Camera Rotators, Focusers, and Accessories (Dew Heaters, etc.) That is, OnStep can be just a Focuser controller, for example, or control any combination of these.
In addition to the wide range of software supported through its ASCOM and INDI Drivers many software packages work directly with it’s LX200 protocol. These include Cartes du Ciel, Stellarium, Sky Safari, etc.
My Hand Controller App for Android devices is available in the Google Play Store. It allows full control of the mount and works nicely in tandem with SkySafari, Stellarium Mobile, etc. Just connect using Bluetooth or IP to have full planetarium type control from a cell-phone or tablet. The Smart Hand Controller and website control options can work with or alongside iOS devices as well.
My Sky Planetarium offers the most advanced integration with OnStep and makes setup/control easier. It also enables some advanced features: like PEC visualization and data upload/download (so you use PecPrep) and n-star align (Eq mount modeling for the best pointing accuracy.)
The Arduino Firmware for OnStep, etc. is at GitHub.
If you’re thinking about building an OnStep please join the OnStep Group at Groups.io for assistance and access to the file areas. Also, be sure to have a look at the Wiki there for detailed information about features and to learn how to build your own.
These are notes pertaining to the development and validation of OnStep hardware and software.