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OnStep on a CG-11

ATM DIY mount 3d printing
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#26 jwheel

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Posted 10 October 2017 - 11:58 AM

Nice! This something I would like to add to my Tak NJP someday.



#27 RAC

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Posted 10 October 2017 - 01:32 PM

Nice! This something I would like to add to my Tak NJP someday.


I've also got an NJP. It's a temma 2 but if something happend to the stock electronics I would be Onstepping it in a heart beat. I'm sure some faster slews could be had with 45 volts to the stepper motors.

#28 hjd1964

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Posted 10 October 2017 - 04:09 PM

Since my OnStep Mini PCB has been mentioned I thought I'd do a post about it for those thinking about building an OnStep.

 

I wanted this PCB to support the Teensy3.2 and the most of the commonly used stepper drivers with a focus on the SSS TMC2130.  I also wanted support for the ST4 port, a full size (durable) USB connector, and a power jack on-board.  For communications beyond the USB port we have the Serial1 port and it's available on three sets of pins (you get to pick one set.)  So that Serial1 port goes to a HC05 Bluetooth, or a SF Bluetooth Mate Silver (RN42,) or a ESP-01 WiFi adapter (the most flexible choice.)  The board was designed to match the size of a low-cost (3 boards for about $45 to $65) ExpressPCB Mini-Board while also fitting within my EM10 mount's motor bay.  Connectors for power, USB, and ST4 can be horizontal or vertical (for panel-mount.)

 

Here's the EM10 controller with vertical connectors as I was working on the PCB and getting the panel to fit my mount.  The PCB in this case had to be built with much consideration to component height to make everything fit neatly behind that panel.  No components were socketed and certain wiring options (the "Aux" pins) were used to allow flashing the ESP8266 WiFi (for firmware update) through the Teensy3.2 since the module can't be easily removed.  The motors, PEC, and polar finder reticule LED all plug into 0.1" pin headers which were added to the bottom of the PCB:

 

OnStep_Mini1.jpg  OnStep_Mini2.jpg

 

 

Once that was done I populated the other two boards.  One for my Z12 Dobsonian (left) and one for the G11 (right.)  These controllers have socketed stepper drivers, Teensy3.2, and ESP-01 modules.  They also have horizontal connectors for power, USB, and ST4; keep in mind they're still built on the same exact PCB design shown above.  The Z12 controller case allows the stepper motor leads to pass through the right side on there way to mini screw down terminals on the PCB.  The G11 case has secure din-connectors for the motors.  The small 1/8" phono jacks are for connecting PEC and limit switches.  Both of these controllers have automotive blade type fuses inside.  Everything is powered from the stepper motor supply, up to 2.5A @ 24VDC for my builds (exact voltage and current capability depends on ratings of the connectors, fuse, etc. but it can go higher.)  These have provision for a cooling fan across the stepper driver heat-sinks but I didn't use it.  All cases were 3D printed and are designed to lay flat during printing to control warping, they look even better in person than the photos.  Build notes, parts list, PCB design file and 3D case/panel .STL files are all available in the Yahoo Group Files section:

 

OnStep_Mini3.jpg

 

Finally, I should note that the (somewhat untested) Teensy3.5 and Teensy3.6 should be compatible with the OnStep Mini.  You just need to jumper the ESP-01 (or BT) off-board and watch how you handle the SPI port holes (which most likely wouldn't be used in this case anyway.)  Naturally the Teensy3.5/3.6 will need pin headers (below) in the Teensy3.2 footprint and probably socket headers (top) for the rest.  The top-side connections include the default St4 port and some other stuff now supported by OnStep on those devices/pins (like the Serial4 port, so you could have WiFi and BT or Ethernet and BT for instance and there's the alert buzzer connection, and the rotator/derotator stepper driver pins.)  Once the Teensy3.5/3.6 are better tested I'll probably do a slight re-design, an "OnStep Mini PCB2" to support it's additional features.


Edited by hjd1964, 11 October 2017 - 07:06 AM.


#29 RAC

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Posted 10 October 2017 - 04:46 PM

Last week I made an updated controller for my 20" dob using a teensy 3.6, it now has bluetooth and wifi. The 3.6 is working just fine but I did run into one problem and that was that the 3.6 is more fussy about its power supply.
I had the 3.2 runing from a 12v usb outlet but the 3.6 on the same outlet would make it go nuts and it would fire the stepper motors at random by itself. I changed to runing everything(bluetooth, wifi and drivers) from a dcdc stepdown converter at 3.3v and that's sorted it.

#30 TonyStar

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Posted 10 October 2017 - 05:35 PM

Howard's mini PCB is the cleanest and most compact packaging option. I used a teensy arduino shield (sparkfun) and stacked the electronics on 2 layers. It makes it easy to expand the system if needed later.

 

post-219573-0-77587000-1495398165.jpg

post-219573-0-49728000-1495398186.jpg


Edited by TonyStar, 10 October 2017 - 06:16 PM.


#31 hjd1964

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Posted 10 October 2017 - 09:11 PM

Last week I made an updated controller for my 20" dob using a teensy 3.6, it now has bluetooth and wifi. The 3.6 is working just fine but I did run into one problem and that was that the 3.6 is more fussy about its power supply.
I had the 3.2 runing from a 12v usb outlet but the 3.6 on the same outlet would make it go nuts and it would fire the stepper motors at random by itself. I changed to runing everything(bluetooth, wifi and drivers) from a dcdc stepdown converter at 3.3v and that's sorted it.

Thanks, this is good to know.  Im not clear on exactly where the esp8266 esp-01? was getting its 3.3v and if the bt was also 3.3v powered... if both were powered from the Teensy3.x vrm that is probably too much for it.  Possibly Teensy3.5 or 3.6 + ESP-01 is too much on its 3.3v vrm also?  For the OnStep mini pcb, if this is the case, i say use a WeMos D1 Mini run on the 5V supply to avoid the issue.



#32 RAC

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Posted 10 October 2017 - 11:03 PM

Yeah I always had the wifi and bluetooth not powered by the teensy. I wanted them separate so I could reprogram the teensy at any time.

#33 kbahey

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Posted 11 October 2017 - 03:57 PM

I used a teensy arduino shield (sparkfun) and stacked the electronics on 2 layers. It makes it easy to expand the system if needed later.

Tony,

 

This is an awesome project.

 

Is it possible to have pictures of the layers, and the underside? That way, we could all see how it is done (just pressed into headers, or pressed then soldered, ...etc.)

 

That is, if it is easy to dismantle to take pictures.



#34 TonyStar

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Posted 11 October 2017 - 08:47 PM

This is how it looks outside the box. All pins are soldered to the board and then connected with wires. It's pretty standard (and tedious) work.

 

IMG_3685.JPG IMG_3687.JPG



#35 kbahey

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Posted 11 October 2017 - 09:51 PM

This is how it looks outside the box. All pins are soldered to the board and then connected with wires. It's pretty standard (and tedious) work.

That is wonderful!

 

Basically the soldering to the Teensy to the shield is straight forward (no decisions on what goes where), and there is little possibility for errors. Also all the components for this stage come from the shield kit. I assume the kits comes with a DC2DC (the black square with a silver side with hole in it). Did you add a fuse?

 

Where did you get the green board from? Is it any specific make/model?

 

I am assuming that soldering the TMC2130s and the WiFi module is also straight forward (just buy short headers [is that the proper term?], and solder all pins on the sides of the TMC and Wifi straight down.

 

For the stepper cable connectors, what are they soldered to?

 

That only leaves the wires, and capacitors as the part that can introduce errors. Can I ask you for a larger picture of the wire side of the green board?

 

Did you use the coin battery at all? Or there the crystal built into the Teensy does the job instead of the RTC?

 

If one wants to add an ST4 port, and a PEC sensor connection, is there planned room for them, or one has to improvise?

 

Thanks for your help and sorry for the repeated questions.



#36 TonyStar

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Posted 11 October 2017 - 10:51 PM

 

 

 

 

Basically the soldering to the Teensy to the shield is straight forward (no decisions on what goes where), and there is little possibility for errors. Also all the components for this stage come from the shield kit. I assume the kits comes with a DC2DC (the black square with a silver side with hole in it). Did you add a fuse?

 

Yes the shield comes with the voltage regulator, I have a fuse on the power cable but you could add one to the shield.

I got the green board and connectors off ebay

I am assuming that soldering the TMC2130s and the WiFi module is also straight forward (just buy short headers [is that the proper term?], and solder all pins on the sides of the TMC and Wifi straight down.

The TMC's (and I guess the WiFi module too) come with the headers

 

For the stepper cable connectors, what are they soldered to?

the connector pins have the same spacing as the holes on the green board, just plug the pins into the hole and solder them

That only leaves the wires, and capacitors as the part that can introduce errors. Can I ask you for a larger picture of the wire side of the green board?

I will send it to you

Did you use the coin battery at all? Or there the crystal built into the Teensy does the job instead of the RTC?

No battery. You don't need the resonator on the shield

If one wants to add an ST4 port, and a PEC sensor connection, is there planned room for them, or one has to improvise?

 

You can add another layer to the stack for that. 


Edited by TonyStar, 11 October 2017 - 11:06 PM.


#37 hjd1964

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Posted 12 October 2017 - 05:34 AM

If planning for more features the shield board(s) should use these (except for the one on top!):

http://www.mouser.co...vBoCrroQAvD_BwE


Edited by hjd1964, 12 October 2017 - 05:44 AM.


#38 kbahey

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Posted 12 October 2017 - 11:18 AM

Tony,

 

Thanks for the answers. I think I can handle this project without prior soldering and electronics experience. The hard part are the wires on the back of the green board, but I will try.

 

Howard,

 

Thanks for your continuing input on this, and answering questions, here and on the Yahoo Group.



#39 TonyStar

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Posted 12 October 2017 - 11:59 AM

BTW, the rest of my dob electronics is also stacked this way. This box packs: arduino Uno, wireless microfocuser (RJ11 port), 2 thermistors and 1 RH meter readers (over BT), rear and boundary layer fan control. 

 

FullSizeRender (13).jpg


Edited by TonyStar, 12 October 2017 - 12:12 PM.


#40 kbahey

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Posted 14 October 2017 - 08:19 PM

Since finding information for a newcomer was more challenging than usual, I created an OnStep Telescope web page on my site where I collected all what I could find in there.

 

Hope this helps newcomers.

 

 



#41 Geo.

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Posted 15 October 2017 - 07:52 AM

I made the motor mountings to connect the NEMA 17 steppers to the existing out of a piece of aluminum using only a table saw, drill press, and an inkjet printer. I drew up the adapter schematic in FreeCad and then (2D) printed it to scale and glued it to the aluminum plates. Then, a machinist punch was used to create a dimple in the aluminum so that the holes could be accurately drilled on the drill press.

 

After a lot of search on ebay, I found some suitable motor couplings to connect the stepper motor shaft to the worm. The trick here was finding couplings that had an outer diameter less than 18 mm (I think) since there is limited clearance on the mounting plate that holds the worm blocks. Most couplings for shafts of this size have an OD of closer to 25mm. This wouldn't be a problem if you have access to a lathe, though.

 

I designed and printed some friction fit covers for the motors that the DIN connector could be screwed to so the stepper wires couldn't get yanked around. This works pretty well, but I've found that the long stepper motors can torque the 2 screw motor mount on the G-11 enough to flex quite a bit.

 

attachicon.gifmotor.jpg

MPJA carries a good variety of couplers at reasonable prices. http://www.mpja.com/...s/products/529/



#42 Geo.

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Posted 15 October 2017 - 08:59 AM

@benula

 

Thanks a lot for all this info.

 

The board for sale on the Yahoo Group (Steve's board) is the older design, based on ArduinoMega2650 and DRV8825 drivers. The Teensy and the TMC2130 are superior.

 

I wish someone would make such a board. I would buy it instead of all the soldering.

Howard Dutton has designed a PCB for the Teensy 3.2 in the ExpressPCB file format. The file (onstep v123.PCB) is available from the Yahoo OnStep group. Howard has GNU licensed it so you can have ExpressPCB print you one for personal use. Unit cost is $90. A group order of 20 units brings that down to $40.

 

Untitled-2.jpg



#43 Geo.

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Posted 15 October 2017 - 09:44 AM

Tony,

 

Thanks for the answers. I think I can handle this project without prior soldering and electronics experience. The hard part are the wires on the back of the green board, but I will try.

 

Howard,

 

Thanks for your continuing input on this, and answering questions, here and on the Yahoo Group.

MPJA is having a sale on the "green" boards, actually these are Arduino UNO prototype shields. http://www.mpja.com/...tinfo/32795 MP/

 

The Teeny 3.2 shield duplicates the UNO's pin outs so shields laid out for the UNO can be used with the Teensy. If space isn't an issue this makes working with the Teensy easier. 

 

If you are going to be doing any soldering get a soldering station. I've used this inexpensive model from MPJA for a few years and have never been disappointed. http://www.mpja.com/...tinfo/15845 TL/

 

On my second pencil ($7) bit I use it a lot. It heats up very quickly and its adjustment help you from not cooking components. I find it's a lot easier to keep the tip of the pencil clean and tinned with a station. Having a clean and tinned tip makes all the difference.

 

Here's a good soldering guide. Have fun!



#44 kbahey

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Posted 15 October 2017 - 01:47 PM

Howard Dutton has designed a PCB for the Teensy 3.2 in the ExpressPCB file format. The file (onstep v123.PCB) is available from the Yahoo OnStep group. Howard has GNU licensed it so you can have ExpressPCB print you one for personal use. Unit cost is $90. A group order of 20 units brings that down to $40.

Yes, I am aware of Howard's design.

 

Of course, it is full featured, but it is also specific to his Takahashi mount in certain ways. First it is a vertical build (more dense, harder for a beginner). Second, there are no sockets for the cables going to the motors (because this PCB is supposed to go inside the mount, and the cables connect internally).

 

Additionally, the format of the OnStep Mini PCB is binary (Eagle CAD), and I could not open the PCB design with KiCAD, nor Fritzing (both are free cross platform PCB CAD programs, since I use Linux only).

 

The design by dragonlost94 is already in Fritzing, and I could open it with the Fritzing program. Fritzing have a very cheap fab service, which would be USD $20 per board, made in Germany (minimum of 3 boards).

 

This in no way is criticism of Howard's work. As with everything in the open source world, he is 'scratching his own itch', and using the tools he knows best. Others, me included, who want to use it have to adapt it to their needs.

 

My end goal is to use OnStep with KStars/Ekos/INDI which I already use for astrophotography and remote telescope control for those cold Canadian nights. INDI is the Linux (and Mac and Windows) equivalent of ASCOM. There is already an INDI driver for OnStep.

 

With a board that has the jumpers routed on the copper, there will be much less possibility for errors or confusion, and soldering will just be a chore, but little possibility of errors.



#45 hjd1964

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Posted 15 October 2017 - 06:17 PM

 

@benula

 

Thanks a lot for all this info.

 

The board for sale on the Yahoo Group (Steve's board) is the older design, based on ArduinoMega2650 and DRV8825 drivers. The Teensy and the TMC2130 are superior.

 

I wish someone would make such a board. I would buy it instead of all the soldering.

Howard Dutton has designed a PCB for the Teensy 3.2 in the ExpressPCB file format. The file (onstep v123.PCB) is available from the Yahoo OnStep group. Howard has GNU licensed it so you can have ExpressPCB print you one for personal use. Unit cost is $90. A group order of 20 units brings that down to $40.

 

attachicon.gifUntitled-2.jpg

 

ExpressPCB Miniboard service is 3 boards for $62 + shipping.  Without soldermask and silkscreen 3 boards for $42.  Can be built vertical or horizontal, much easier/less planning horizontal.  



#46 brave_ulysses

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Posted 15 October 2017 - 07:16 PM

other pcb houses to check out:

 

https://www.seeedstu...fusion_pcb.html

 

https://dirtypcbs.com/store/pcbs

 

https://oshpark.com/

 

https://www.itead.cc...rototyping.html


Edited by brave_ulysses, 15 October 2017 - 07:17 PM.


#47 kbahey

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Posted 16 October 2017 - 09:58 PM

A user on the Yahoo Group pointed to this PCB manufacturer. They are very very inexpensive, and the turnaround was 20 days (to Italy).

 

The typical 100 x 100 mm board costs $2.63 ($13.13 for a quantity of 5).

 

They require Gerber files.

 

https://easyeda.com/order



#48 kbahey

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Posted 27 October 2017 - 12:07 PM

An update on OnStep.

 

Howard has designed a new PCB, called OnStep Max, with important additions:

  • First, it is available at EasyEDA, which are really low cost (you can get 5 PCBs for ~ $14 plus ~ $8 shipping).
  • Second, it has allowance of two additional stepper controller, one for the focuser (using his focuser), and the other for a second focuser (autoguide scope), or a rotator for framing. 

I created a bill of material for this board. This BOM can be uploaded directly to DigiKey, and they will create a cart automatically from it, reducing the tedious amount of work needed to order.

 

Note that the BOM has not verified by myself (an electronics newbie, so there may be mistakes) or anyone else so far. If you do use it, and see something missing, then please let me know (link to feedback form in the web page below).

 

The BOM and updated info on all PCBs are on updated my web page: OnStep: A full featured open telescope controller to include links to the above.



#49 dwkdnvr

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Posted 29 October 2017 - 03:54 PM

Howard's mini PCB is the cleanest and most compact packaging option. I used a teensy arduino shield (sparkfun) and stacked the electronics on 2 layers. It makes it easy to expand the system if needed later.

 

attachicon.gifpost-219573-0-77587000-1495398165.jpg

attachicon.gifpost-219573-0-49728000-1495398186.jpg

 

That's a nice setup.  So that's the Sparkfun Teensy Arduino Shield adapter, along with the Proto Shield on top?  That looks manageable, particularly since my plan is to run via USB rather than wifi since I'm planning EAA style viewing and so will have a tiny pc at the mount.  Do you have STLs for the enclosure?

 

I picked up the TMC2100 drivers from Filastruder. It seems that most of you are using the 2130 version. Did I make a mistake with the 2100? I had thought that they were basically equivalent for OnStep purposes, but if there is a benefit to the 2130's now would be the time to change.

 

I've assembled most of the pieces for a pillow-block EQ mount and OnStep drive system.  I just have to get moving on actual work......My current decision point is that I have 1" steel shafts and pillow blocks that I got as an inexpensive 'first try' platform before moving on to a bigger 'real' mount. I think the 1" shafts should be ok for the 8" f/4 that I have (20 lbs), but I have a 1.5" shaft Byers worm kit I got in preparation for the larger mount project. So, I either have to figure out a bushing arrangement to adapt it to the 1" shaft or else get new 1.5" parts for one axis (~$200).   The other axis will the the Byers drive from an old Celestron fork mount, which I'll also have to adapt and figure out a clutch arrangement, but that doesn't change much either way.

 

I got a 3d printer and tiny little cnc machine (Millright M3) using this project as the excuse/justification. Progress has been slow, but at least not zero.



#50 TonyStar

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Posted 29 October 2017 - 05:59 PM

That's a nice setup.  So that's the Sparkfun Teensy Arduino Shield adapter, along with the Proto Shield on top? 

Yep

 

 

 Do you have STLs for the enclosure?

I'll post the files on Thingiverse for those you want to print them




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