This is a 5-minute video of my Tak EM10B mount moving around a little then returning to the home positon. It's goto top speed is just a little over 1 degree per second with the motors being the limiting factor. All OnStep hardware is in the motor bay of the mount (very limited space.) The cord seen going to the mount is the DC power cord, control is via Bluetooth using my Android tablet and/or across USB using the connector next to the power cord seen in the video. Note: I later switched to my OnStep MiniPCB based controller with better stepper drivers and WiFi instead of Bluetooth, slew speed is now 3.5 degrees per second.

If you find OnStep useful, please help support this project:
Since I aquired 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 goto system for stepper motor equipped mounts. It was designed, from the beginning, as a more or less general purpose system and provisions were made in the firmware to allow for use on a variety of mounts including Equatorial (GEM, Fork, etc.) and Alt/Az (Dobsonian, etc.) It uses an LX200 like computer command set with a few extensions to suit hand-controllerless operation.

In addition to the wide range of software supported through it's ASCOM driver, 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 you to Un-Park or Align the mount to get going, then startup SkySafari (for example) and connect (using Bluetooth or IP) to have a full planetarium type control application... All from a cell-phone or tablet.

If you're thinking about building an OnStep please join the OnStep Group for assistance and access to the file areas.

Also, be sure to have a look at the Wiki for detailed information about features and to learn how to build your own.

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 ASCOM Telescope Driver download page also has a detailed command description.

There's even an INDI OnStep driver for Linux and CdC, KStars, etc.

The Android App for OnStep is at the Google Play Store.

The Arduino Firmware for OnStep, etc. is at GitHub.

Even though you should use, here's a link to the old OnStep Yahoo Group if you'd like to see the messages/files.

These are notes pertaining to the development and validation of OnStep hardware and software.