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, usually for stepper motor equipped mounts though any step/dir interface motor driver (including servo) should work. 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 and Alt/Az (GEM, Fork, Dobsonian, etc.) It uses an LX200 like computer command set with a few extensions to suit hand controller-less operation.
There's a telescope hand controller App for Android (free in the Google Play Store,) an option to control through a website (Smart Web Server,) and a dedicated physical hand controller (Smart Hand Controller.) Or, on a PC there's ASCOM and INDI drivers for control. These options allow you to setup and control OnStep using a wide range of software including my Sky Planetarium, Cartes du Ciel, Stellarium, SkySafari, KStars, PHD2, etc. You can see most of the control possibilities in the diagram below:
Also, please visit my StellarJourney.com site for updates, links to OnStep resources, my other astronomy software, or to see some Images taken with the assistance of my OnStep operated mounts.
If you find OnStep useful and would like to show your appreciation and support please consider making a small monetary donation. This keeps me motivated and helps cover expenses associated with my projects.
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Re: CGE Pro help
davel
Hello, Chad; One question, have you finalized the design of the motor mount adapter yet? As I have mentioned before, I have a customer's CGE Pro that has dead electronics, and we are planning a move to the OnStep system. Once I have a printable file I will commence with the electronics and software. Your printed adapter looks like a winner, for simplicity's sake and my sanity. I'm planning on getting the adapters printed at Shapeways if no alternate comes around. I have NO previous experience with Shapeways, is the Fusion file linked in your post sufficient to send them, or do I need other detail drawings? There is a possibility of getting the final design machined at reasonable cost, but I would like to try out the system before committing to a machined part. 3D prototyping is a real advance in this hobby. Thanks, Dave
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Re: Steppers with Planetary Gear boxes
George Cushing
It's difficult to say what would be suitable without a brief description of your intended project.
This NEMA17 produces about 18 watts power and 62 Oz-in torque before considering the gear reduction. That which gets you to something like 6.5ft-lb. The motor has a 8mm output shaft to deal with all that torque. Great motor for an extruder, if that's what you want. General rule: avoid reducers involving gears. They create backlash. Yes, most mounts violate this rule by employing worm gears. The rational is they produce large reductions and we only have to deal with one gear interface to get it. BTW, 4mm output shafts aren't common. Step motors come with 3, 5, 6 and 8mm shafts. Four mm is 0.1574803", close to 5/32" (0.15625), but the current NEMA (National Electrical Manufactures' Assn (U.S.A)) were adapted from those that adopted 1/8th, 3/16th, 1/4, and 5/16th inch shafts to the nearest metric size.
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Re: Raspberry PI Kills onStep
#wemos
User error. Added a power switch and had a solder short.
On Wed, Aug 4, 2021, 8:38 AM George Cushing <stm32bluepill@...> wrote: Which controller?
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Re: Raspberry PI Kills onStep
#wemos
George Cushing
Which controller?
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Re: Meade RCX400 Control board
George Cushing
I've sold about 125 kits and assembled controllers powered by the ESP32 and found it to be the least problematic of any of the processors. It powers the MaxESP32, which is a fairly feature rich and thus more complex controller. I've put about 70 out in the world. So implementing their features generates frequent questions, but the ESP32, which is found in four OnStep controllers I'm familiar with, is the easy part.
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Steppers with Planetary Gear boxes
Peter Boreland
I would appreciate input on the idea of using steppers with planetary gearboxes, or a source of small inline planetary gearboxes that have output shafts of 1/4" or less (4mm for instance).
Here is an example of one such motor: https://www.oyostepper.com/goods-300-Nema-17-Stepper-Motor-Bipolar-L%3D48mm-w-Gear-Ratio-19-1-Planetary-Gearbox.html but its output shaft is too big at 8mm. I'm sure there are better options. I've only just started my hunt. This would be used for the Dec axis only where a step size of less than 0.56 arc-sec if preferred for optimal guiding. Something in the range of 0.14 arc-sec. Could be larger 0.17 or smaller 0.11 works well too. Peter
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Re: OLED 1.3inch resolution issue fix
Thanks Dave
I reupload tomorrow n try again. :) The for your help ~ appreciate .
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Re: Raspberry PI Kills onStep
#wemos
It would be interesting to know the OnStep HW you use.
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Re: CGE conversion
alekstad46@...
I connected the motor, but in the Onstep app, pressing the focus down button only rotates in one direction. As long as I keep the button pressed, the motor rotates in one direction, as soon as I release the button, the motor returns back to the starting position. There is no rotation on pressing the up button in the other direction.
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Raspberry PI Kills onStep
#wemos
I'm trying to use my OnStep controller with a Raspberry Pi. If I do not have power plugged into the controller, just the pi via USB, I can see OnStep and configure kstars, etc. But when I plug the power into the OnStep controller, It dies. Power with no USB works fine. USB with no power works, but no power to steppers. Power and USB kills onStep. Power and USB on my laptop does not have this effect.
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Re: Meade RCX400 Control board
Claudio Arena
Thank you both for the information. I will look better at both options.
In case I went with keeping the DC servo, and making the conversion to Step/Dir interface, is there a preferred micro/control board at the moment? From what I've seen the Mega2560 is discouraged, and the ESP32 might be a bit buggy. Is this correct? If I wanted to put the control board inside the mount, would the MiniPCB version 1 be a good option? Or would you suggest me something else to get started? Thanks!
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David Underwood
I posted earlier about go- to going too far. This was resolved for DEC axis when I found a GT2. pully. which was in a package as 16 tooth was really 20. Am I missing something in bluepill config. ?
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Re: CGE conversion
Alexander Varakin
You can see how I connected the focuser on the 2nd picture: The driver for the focuser is the 2nd from the left, purple in color. I used DRV8825 for focuser which is ok for this purpose
Here is my config.h. If I remember correctly, I just flipped #define FOCUSER1 from OFF to ON: // AXIS4 FOCUSER 1
// see https://onstep.groups.io/g/main/wiki/6-Configuration#AXIS4
#define FOCUSER1 ON // OFF, ON to enable this focuser. Option
#define AXIS4_STEPS_PER_MICRON 0.5 // 0.5, n. Steps per micrometer. Figure this out by testing or other means. Adjust
#define AXIS4_SLEW_RATE_DESIRED 200 // 500, n, Where n=200..5000 (um/s.) Max microns/second. In DC mode, max pwr % Adjust
#define AXIS4_DRIVER_MODEL OFF // OFF, TMC2130, TMC5160. Leave OFF for all drivers models except these. Option
#define AXIS4_DRIVER_MICROSTEPS OFF // OFF, n. Microstep mode when tracking. For TMC2130, TMC5160. Option
#define AXIS4_DRIVER_IHOLD OFF // OFF, n, (mA.) Current standstill. OFF uses IRUN/2.0. " Option
#define AXIS4_DRIVER_IRUN OFF // OFF, n, (mA.) Current tracking, appropriate for stepper/driver/etc. " Option
#define AXIS4_DRIVER_POWER_DOWN OFF // OFF, ON Powers off the motor at stand-still. Option
#define AXIS4_DRIVER_REVERSE OFF // OFF, ON Reverses movement direction, or reverse wiring instead to correct. Option
#define AXIS4_DRIVER_DC_MODE OFF // OFF, DRV8825 for pwm dc motor control on stepper driver outputs. Option
#define AXIS4_LIMIT_MIN_RATE 50 // 50, n. Where n=1..1000 (um/s.) Minimum microns/second. In DC mode, min pwr. Adjust
#define AXIS4_LIMIT_MIN 0 // 0, n. Where n=0..500 (millimeters.) Minimum allowed position. Adjust
#define AXIS4_LIMIT_MAX 50 // 50, n. Where n=0..500 (millimeters.) Maximum allowed position. Adjust
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Re: Random N / S direction change Onstep Android app.
Thank you for all the answers.
Indeed it's my fault because having a new mount (friction mount from JTW Astronomy) I wanted to see its behavior during changes of direction ..... without using a celestial map !! therefore impossible for me to know where the telescope was pointing! and indeed, if at Onstep startup it points the NPC and my telescope points in another direction, there can only be one big problem! Thank you all once again!
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Re: Random N / S direction change Onstep Android app.
This is the most Frequently Asked Question on OnStep. Read the link.
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Re: Focuser for MaxEsp3
Seven Jones
Thank you Dave. That explains a lot.
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Re: Random N / S direction change Onstep Android app.
It doesn't really depend on how close you are to Polaris. It has everything to do with true North and the direction you pressed on the controller.
Here is how I explain the behavior. The basic rule is that it always wants to go North when you press the N button. OnStep starts with the telescope at NCP (North Celestial pole). Pressing the N button will cause the telescope to head South. This is the only direction it can go since it is already at North. Release the button and press North again. It will reverse direction because now it can and will go North. Keep holding the button passing the polar axis (scope aligned with mount) and it will continue, but now it is actually going South. Let go of the button and press North again. It will reverse direction again, heading North. This can take awhile to wrap your head around. Play with it and it will become obvious. Of course, all of this is reversed for our friends below the equator.
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Francois94
Here is my setup and indeed , if i stand south of the mount , pushing the 3 O'clock button , the RA axis is turning CCW:
 
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Re: Random N / S direction change Onstep Android app.
Chad Gray
I also questioned this. The N/S gets flipped depending on how close you are to Polaris. I think there is an explanation on the FAQ.
On Tue, Aug 3, 2021 at 11:16 AM adraasch <araasch@...> wrote:
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Re: Random N / S direction change Onstep Android app.
adraasch
How close to the pole are you when you make these moves? Arlen
On Tue, Aug 3, 2021 at 11:07 AM Dahle <dahle@...> wrote:
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