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                     ONSTEP UNIVERSAL MOUNT CONTROLLER - G11 - V1 This is an original and very pretty programming project by Howard Dutton, As is a very complete and customizable system i decided to make my own hardware design using Corel Draw X6 and my 3020 CNC. Enclosure of choice was a black anodized aluminum project box, work with aluminum is much hard than ABS plastic but the quality is the best, aluminum enclosure works as electromagnetic shield and heatsink sametime. OnStep Autostart sidereal tracking on power up, yellow leds indicates power is on, green leds indicates the axis is tracking or moving. The basics Onstep works as an extended LX-200 control protocol, it becomes with an Android app and a built-in Wi-Fi web server with configuration and information pages. It has an ASCOM windows driver for the unit and another ASCOM windows driver for the focuser. OnStep can be controlled simultaneously from the USB COM port, WiFi Webserver and Android app, that means, every moving or command take effect on all conected software. AN AT Mega 2560 it has 2 cristal oscilators; one for the COM port and another one for the MCU, this means that the system maintains the tracking precise. The WiFi module used is an ESP-07s, industrial grade, it has an electromagnetic shield and a connector to extend the antenna out of the enclosure, for obvious reasons. The system can be used in ecuatorial mounts or alt-azimutal mounts making the right changes on the firmware, you will find the firmware used for the Losmandy G11 at the end of this page. Stepper drivers and motors Many stepper drivers can be used but the right way is a good combination between the driver model, the stepper motors and the power source, 12V in this case. For this configuraton 0.9º Stepper Motors and TMC2100 drivers are used for RA/DEC and TMC2208 for the focus motor. TMC2100 drivers are configured to 16 micro-stepping SpreadCycle mode with 256 micro-step interpolation. The reduction factor for Losmandy G11 is 1:1 (Direct to WormGear), so the final values are this ones: Micro-Steps per Degree:               6400 Micro-Steps per Worm Rotation:  16000 (600 seconds to complete a full worm rotation) Resolution (interpolated at 256 micro-steps): 0,0023 arc-secs Minimum move: 0,037 arc-secs (interpolated resolution x 16) PEC Sense OnStep PEC can be permanent and stored onto MCU eeprom, and start it via software but aditionally we can call the recorded PEC to re-start automatically when the worm completes an exact full rotation. PEC Sense is optional to use and consits on a simple 2 pin micro-switch installed on the mount worm gear and conected to Onstep PEC Sense imput, when the circuit is shorted PEC restarts. The G11 worm gear takes 240s to complete a full worm rotation, OnStep G11 firmware is configured to record 240s, for other mounts can be more, up to 3384s. If microswitch installed, the green led lights up when the worm gear completes a full rotation, and then, if configured, recorded PEC restarts. The right moment to start recording PEC is just in the moment when the green led light up. This option if installed is very useful because we can move the mount manually but PEC will restart allways at the correct moment. Refraction rate compensation This feature adjusts tracking rate to compensate atmospheric refraction depending on the altitude where the telescope is pointing to. By default off, can be turned on/off throught Webserver or Android app. I didnt test it but may be much helpful, seems to be in development but some users may had sucess with it, more info on main author discussions forum Limit Switch This optional feature is enabled on the firmware but take no effect unless you close the circuit between limit pin outs. Implemented for security purposes, you can install 2 micro-switch on both sides of your AR axis to prevent the mount hit the tripod or post. Optional but not fully needed, OnStep limits are hardware/software configurable. Focuser This feature is enabled on firmware, you can control a compatible focusser system based on a stepper mottor or make your own focuser, to use this feature you need to know your stepper focus mottor specs such step angle and current, the driver max continuous current is 1A. To config driver step size there are 3 micro-switchs near to the TMC2208 driver on the PCB, by default is configured to half step with 256uSteps interpolation, other focuser settings can be configured on the firmware or ASCOM Driver.  
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AR & DEC Axis - Click to enlarge
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WebServer config pages (Click to enlarge)
Web Server In AP mode the webserver configuration pages are located on IP Adress, its accesible via web browser by the user, by default OnStep starts in AP mode, the default password is “password” The command channel is located on this is where the aplications such onstep app, SkySafari,  Stellarium,  ASCOM telescope driver, ASCOM focus driver and other softwars connects to. In Station mode Onstep connects to a configured router credentials, DHCP should be enabled in most cases to easy identifi what IP has been assigned to OnStep (checking the router local nerwork tab)                                                                     
Android app All configurations can be done via android app too, adinionally, the android app has a large database of solar system and deep space objects, custom objects can be added too manually. The interface works very quick due to the main controll is made from OnStep MCU.
Android app config pages (Click to enlarge)
ASCOM Telescope and focuser drivers Provide compatibility with all telescope and focuser control software, telescope control and focus control can be controlled simultaneously throught IP Adress or wired USB COM port.
System mounting on a Losmandy G11 Custom motor chasis has been made for this project to meet the requeriments of keep the motor axis as near as possible to the G11 supports, this video shows how to easy become to install the kit.
Support This project supossed to me gratefully to make it, as is a very complete, customizable, open source code and works extraordinary well, also has increased my knowledge and skills about electronics design from start to end a complete electronic project with a pretty enclosure. Thanks to Howard Dutton, the firmware developper for his nice work. Firmware used for Losmandy G11 setup, (North or South Hemisfere side of pier) Both axis can be inverted too from Android APP but this firmwares are for no-inverted axis setup. OnStep_G11_North_V1.hex  OnStep_G11_South_V1.hex V1 COM Port driver Windows/Mac/Linux/Android: ASCOM Telescope driver windows: v1.40  DOWNLOAD ASCOM Focuser driver windows: v1.31  DOWNLOAD Android App: v1.81  DOWNLOAD Firmware upload tool: *In order to change the firmware, XLoader must be installed first, just download and extract. The drive must be external powered. Open “XLoader.exe” and select Mega 2560 board, the hex file and COM port, dont change baudrate. Click “Upload” button and wait for the “Uploaded” message, its take about a minute to finish uploading. Reset the drive by power-off and power-on. System specs Current comsumption: Max 1A at 12VDC, 12 - 13V is the recomended voltage imput, stepper drivers current output has been fine adjusted to balance stepper motor torque, source voltage, driver heating and GoTo max rate, wich is by default 360X (1,5º/s”), GoTo max rate is limited to safe mode, wich is the mode where there is no risk to motor stahl even with the mount counterweights wrong balanced. Max GoTo rate is still in development, powering the driver at 15V instead of 12,5V could probably increase the speed up to 500X in safe mode but a little change on firmware need to be done for this. The low driver heating is dispelled throught the aluminum enclosure, keep the driver heating low increase the efficiency a lot due to the driver MOSFET electrical resistance increases with heating. Micro-Steps per Degree:               6400 Micro-Steps per Worm Rotation:   6400 (240 seconds to complete a full worm rotation) Resolution (interpolated at 256 micro-steps): 0,0023 arc-secs Minimum move: 0,037 arc-secs (interpolated resolution x 16) Reduction factor 1:1 (Direct coupled to wormgear) ST4 RJ12 6P6C Pinout Pin #1   GND Pin #2   RA -       (West) Pin #3   DEC +   (North) Pin #4   RA +      (East) Pin #5   DEC -    (South) Pin #6   GND        If you want to implement this system to your mount mail to
June 2018 By
     Holding solution, bore D=5,5mm. Can be fixed to a post using screws or Nylon fasteners
System fully installed - Click to enlarge
Original project developper, Howard Dutton: Main project discussion, forum, support and resources: