Arduino telescope goto for equatorial and alt/az mounts
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addons Timeout extension for command channel causes problems Sep 25, 2018
doc/es Spanish translation of configuration comments Mar 12, 2018
src Fix for power down logic rotator Jul 27, 2018
.gitignore Fixed git ignore, added Config.h files Jan 31, 2018
AdvancedDriverSetup.txt Nicer comments Feb 21, 2018
Align.h Refactoring May 18, 2018
Align.ino Changed DBG to just D, also replaced D2 with DH (dump hex). May 23, 2018
Astro.ino Merge branch 'Beta' into Alpha Jun 21, 2018
Command.ino Changed :GX81# get date to fixed width format Oct 4, 2018
Config.Classic.h Added sync pier side option Jun 6, 2018
Config.MaxPCB.h Added separate auto power down option for focusers/rotator Aug 6, 2018
Config.Mega2560Alt.h Focuser/rotator control isn't supported by this pinmap Aug 6, 2018
Config.MiniPCB.h Added sync pier side option Jun 6, 2018
Config.Ramps14.h Added separate auto power down option for focusers/rotator Aug 6, 2018
Config.STM32.h Added support for auto power down of rotator/focusers Aug 6, 2018
Config.TM4C.h Correction, power down control not available in TM4C pinmap Aug 6, 2018
Constants.h Moved debug macros back into OnStep.ino May 25, 2018
Globals.h Fixed typo Oct 3, 2018
Goto.ino Fix for sync not working when at home Sep 13, 2018
Guide.ino Merge branch 'Beta' into Alpha Jun 21, 2018
Home.ino Axis1 celestial pole pos in steps uses floating point May 22, 2018
Initialize.ino Added ability to change the default guide rate Oct 2, 2018
LICENSE.txt Pointed to actual license file, instead of a stub one. Jan 9, 2018
MoveTo.ino forceSlewStop shouldn't set false until after end of slew Jun 11, 2018
OnStep.ino Upped patch level Oct 4, 2018
Park.ino Refactoring Apr 13, 2018
Pec.ino Improved comments Jan 9, 2018
Pins.Classic.h Refactoring/reorganization May 15, 2018
Pins.MaxPCB.h Refactoring/reorganization May 15, 2018
Pins.Mega2560Alt.h Refactoring May 15, 2018
Pins.MiniPCB.h Merge branch 'Beta' into Alpha Jun 21, 2018
Pins.Ramps14.h Refactoring/reorganization May 15, 2018
Pins.TM4C.h Refactoring/reorganization May 15, 2018 Update Jun 21, 2018
StepMode.ino Fixed stepper driver init bug I recently introduced May 30, 2018
Timer.ino Fixed variable name Jul 26, 2018
Validate.h Validation of PECBufferSize Jul 15, 2018

OnStep Telescope Controller

Important Note



What is OnStep?

OnStep is a computerized telescope goto controller, based on Teensy or Arduino control of stepper motors.

It supports Equatorial Mounts (GEM, Fork, etc.) as well as Alt-Az mounts (including Dobsonians, and the like.)

OnStep 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.


OnStep supports a wide variety of connection options. Either two or three serial "command channels" can be utilized. One of the these is normally devoted to a USB connection and for the other(s) choose from the following:

  • Bluetooth
  • ESP8266 WiFi
  • Arduino M0/Ethernet Shield
  • Even another USB port or RS232 serial isn't very difficult to add.

Other software in the OnStep ecosystem include:

  • an ASCOM driver (with IP and Serial support),
  • an Android App useable over WiFi or Bluetooth equipped Phones/Tablets (version 2.3.3 or later),
  • a "built-in" website (on the Ethernet and/or WiFi device),
  • a full planetarium program that controls all features (Sky Planetarium).

OnStep is compatible with the LX200 protocol. This means it can be controlled from other planetarium software, like: Sky Safari, CdC (even without ASCOM), Stellarium, etc.

There are also INDI drivers so it can be used from Linux, with CdC or KStars.


Detailed documentation, including the full set of features, detailed designs for PCBs, instructions on how to build a controller, how to configure the firmware for your particular mount, can all be found the OnStep Group Wiki.


Questions and discussion should be on the mailing list (also accessible via the web) at the OnStep Group.


OnStep is open source free software, licensed under the GPL.

See LICENSE.txt file.


Howard Dutton