My Skywatcher 150p on an EQ3-2 mount and OnStep STM32 Bluepill #EQ3


Frank
 

Hello,

i want to say thank you for this great community, software and support. I learned much due this project and teaches me to go "OnStep" by step ;-) There is still some fine-tuning to do, but the weather is currently very cloudy.

I converted a Skywatcher EQ3-2 Mount and created some own and some modified 3D Printer files to fit my requirements. 

My Setup:
Skywatcher 150p telescope
Skywatcher EQ3-2 mount (aluminium tripod with some modifications to improve stability and prevent shaking)

2x Nema 17 / 200Steps
R.A. is using 20:60 Pulleys (160mm belt)
DEC is using 20:40 Pulleys (146mm belt)
TMC2130 with microstepping: 64 (GOTO 16)
STM32 on STM32 BluePill PCB (Wifi and Bluetooth) (soldered on a minimal setup)
Case bought on amazon: https://www.amazon.de/gp/product/B005DRPCBW
Old Nexus 5x as Hand Controller for initial setup after alignment. (Bluetooth)
12v battery pack 4.500mAh (place on the tripod middle shelf, to improve stability) 
My iPhone for Skysafari

Printed parts:
RA and DEC motor mount
Brachet which is attached to the OnStep case (to attach the case with velcro)
Phone mount (with plotted "OnStep" Sticker)
Polar Alignment scope illuminator (from thingiverse)

My created/modified files attached.
Link to polar finder illuminator:
https://www.thingiverse.com/thing:4419314





Thank you for all the support and the love which you are giving to this project. You rock!

Have a nice day and clear skies! 

Frank


Dave Schwartz
 

A very nice job... congratulations!

On 2021-06-05 5:30 a.m., Frank wrote:
Hello,

i want to say thank you for this great community, software and support. I learned much due this project and teaches me to go "OnStep" by step ;-) There is still some fine-tuning to do, but the weather is currently very cloudy.

I converted a Skywatcher EQ3-2 Mount and created some own and some modified 3D Printer files to fit my requirements.

My Setup:
Skywatcher 150p telescope
Skywatcher EQ3-2 mount (aluminium tripod with some modifications to improve stability and prevent shaking)

2x Nema 17 / 200Steps
R.A. is using 20:60 Pulleys (160mm belt)
DEC is using 20:40 Pulleys (146mm belt)
TMC2130 with microstepping: 64 (GOTO 16)
STM32 on STM32 BluePill PCB (Wifi and Bluetooth) (soldered on a minimal setup)
Case bought on amazon: https://www.amazon.de/gp/product/B005DRPCBW
Old Nexus 5x as Hand Controller for initial setup after alignment. (Bluetooth)
12v battery pack 4.500mAh (place on the tripod middle shelf, to improve stability)
My iPhone for Skysafari

Printed parts:
RA and DEC motor mount
Brachet which is attached to the OnStep case (to attach the case with velcro)
Phone mount (with plotted "OnStep" Sticker)
Polar Alignment scope illuminator (from thingiverse)

My created/modified files attached.
Link to polar finder illuminator:
https://www.thingiverse.com/thing:4419314 <https://www.thingiverse.com/thing:4419314>





Thank you for all the support and the love which you are giving to this project. You rock!

Have a nice day and clear skies!

Frank


Mike Ahner
 

Well done, Frank! Very nice, indeed!


Khalid Baheyeldin
 

Frank,

Thanks for sharing. It is now in the showcase page.

One question, how did you connect the Bluetooth and WiFi at the same time?
Which pins, ...etc.?


Frank
 

On Sat, Jun 5, 2021 at 08:52 PM, Khalid Baheyeldin wrote:
Frank,

Thanks for sharing. It is now in the showcase page.

One question, how did you connect the Bluetooth and WiFi at the same time?
Which pins, ...etc.?
Hello Khalid,

thank you! I extended the RX and TX pins on the CP2012 module. There i connected a HC-06 bluetooth module for TX and RX. The GND is directly from the STM32 and J3 on the BluePill board gives me 5v to power up. The CP2012 still works and with programming/flash mode on the STM32, too.  No Code Change was needed. Maybe i will need to change the code to change the HC-06 name, but this is cosmetic for me and is only interesting if you connect the first time.

Thank you :-)


Khalid Baheyeldin
 

On Sun, Jun 6, 2021 at 11:00 AM, Frank wrote:
I extended the RX and TX pins on the CP2012 module. There i connected a HC-06 bluetooth module for TX and RX. The GND is directly from the STM32 and J3 on the BluePill board gives me 5v to power up. The CP2012 still works and with programming/flash mode on the STM32, too.  No Code Change was needed. Maybe i will need to change the code to change the HC-06 name, but this is cosmetic for me and is only interesting if you connect the first time.
That works ...

There is a limitation of course, is that the microUSB port on the CP2102 module cannot be connected to USB (PC, Raspberry Pi, ...etc) as long as Bluetooth is connected too.


Frank
 

On Sun, Jun 6, 2021 at 05:54 PM, Khalid Baheyeldin wrote:That works ...There is a limitation of course, is that the microUSB port on the CP2102 module cannot be connected to USB (PC, Raspberry Pi, ...etc) as long as Bluetooth is connected too
Yes, but i am ok with that :-) i only need usb for flashing the stm32.


Francois94
 

Hello Franck , nice job !!
Would you mind posting a link for the 40/60T pulley ? I've already made some tests with 3D printed pulley , it works , but not that strong enough for "outside" use :-)
As clearance is a problem on this EQ3-2 mount , pulley size is quite important .
Regards.


Frank
 


Francois94
 

Hello,
thanks for the link .
I've received my pulley , and i have some contact when moving from 60T RA pulley and the brake lever :-(
It looks like that on your picture , i can see a kind of adapter between the pulley and the eq3-2 axis , could you please confirm this ?


Frank
 

Hi

yes, there is a coupler!

attached the link

https://www.ebay.de/itm/Wellenkupplung-Mini-D9L20-Shaft-Coupler-Messing-starr-3D-Druck-CNC-Modellbau-kV-/163289328297?_trksid=p2349624.m46890.l49286

You need a small metal bold or a screw to attach the pulley to the bolt. 

i had a metal bolt laying around, which i had to short it a little bit. 


Yen Quy <quy_yen@...>
 

You can use this, https://www.amazon.com/gp/product/B07TV3LMHS/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1
and this, https://www.amazon.com/gp/product/B07KY99QKF/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1
 To extend the RA shaft.  if you turn around the pulley then chances are you don't have to change your existing bracket.  That's what I did.


Yen Quy <quy_yen@...>
 

Another picture showing the coupler:


Frank
 

Hi yen quy!

looks line you have got the same mount, right? Is you ration of the worms 130:1 and 65:1,too?

i currently struggle with the accuracy :-(


Yen Quy <quy_yen@...>
 

Hi Frank,
Yea, my RA is 130, my DEC is 65.  I built the rDuinoScope project for it using pulleys 48 and 16 on both axes, for me the goto is pretty accurate,  If I got the polar alignment correct, I could get the Arcturus, Vega and Dubhe in the scope, not really in center but they're in there. 
I found this OnStep project and like it, so I'd like to build one for myself.  My Blue Pill PCB boards (13 of them :-) ) will arrive by the end of next week, already got most of the components. So I'm ready for the project.
I also got the FYSETC coming next week too :-)
And I just got myself a new EQM35-PRO yesterday.  I think I got addicted with this stuffs :-) 


Yen Quy <quy_yen@...>
 

I see you use 20:40 on the DEC.  I had problem with accuracy when I used 30:16 on the DEC.  The accuracy improves a lot when changed to 48:16 on both.


Frank
 

I was able to test it last night, there wasn't much clear skies this spring and summer in Germany. Did you had the accuracy issue with OnStep or rDuinoScope? 

I did the alignment and tested Arcturus or Dubhe, there is still about 20-30 degrees missing. If I manually put arcturus in alignment and press align, I can move to Dubhe which is not in my scope... it points near to Mirak but, when I goto back to arcturus its precise.

Today I will do the debugging which is documented in the FAQ:
https://onstep.groups.io/g/main/wiki/7118 

Maybe this will help to understand what's going wrong here ;-) I will report my testing.


Yen Quy <quy_yen@...>
 

Hi Frank, 
Do you have any 48 and 16 teeth or better yet, 12 teeth?  I think the greater the ratio the more accurate it's is.  I got them from here: 
https://www.aliexpress.com/item/32879878867.html?spm=a2g0s.9042311.0.0.2a5f4c4d2IgD79
It's inexpensive enough I ordered a dozen!  I'm using 16:48 now, I'm waiting for the 12 teeth to come, then I'll replace the 16 with the 12 to have 4:1 ratio. Even now, with 3:1 ratio, 48:16, it's pretty accurate for me using rDuinoScope.  I compared the goto between my rDuinoScope and EQM35-Pro, it's close enough!
I'll build the Onscope in a week, then we'll see.


Frank
 

hi, not at home at the moment... I did some testing some minutes ago, my issue is the DEC Axis. 

Due there are new customs regulations in the EU it does not make sense anymore to order this at aliexpress. But other people run it with the same pulley. 

Attached the test protocol, maybe Khalid or someone has got a hint for me?

These are my settings: 
Axis 2:
1:65 Wormwheel for DEC and 20 to 40 Gear reduction depends on the pulley

Drive design:
  • Motors and drive components move the mount reliably, not slipping or skipping steps.

CHECK OK

 

Configuration:

  • See the Wiki section here for "Preliminary Firmware Configuration" instructions.

CHECK OK

  • Correct stepper micro-step mode is set and actually used in the driver (hardware/connections setup.)

CHECK OK

  • Motor direction of motion is correct.
    • Use a planetarium program for control, start tracking; these instructions apply Eq mounts.

Its a EQ Mount OK

  • Move Declination a little (10 or 20 deg.) left and right of the home position (NCP/SCP) and watching from behind the mount see if the telescope movement matches the screen.  Reverse Axis2 if it goes the wrong way.

MATCHES the screen OK

  • Once that is working do a goto to a point half way up in the sky but not too far in home position (40 degrees away or so.)  If it points down toward the ground RA needs to be reversed.

USED MIRACH -> Points UP not down OK

  • Correct steps per degree settings for Axis1 and Axis2; these instructions apply Eq mounts.
    • Use a planetarium program for control, start tracking.
    • Move Axis2/Declination a fair bit (45 deg.) left or right of the home position (NCP/SCP) and take note of the angular distance traveled, is it about 45 degrees?

Started at 90° scale MOVED 45 ° in OnStep ends at about 55° on scale -> 10° missing

Moved 90 ° in Onset ends at about 19° -> 20° missing

  • Move Axis1/RA to near the Meridian and 0 degrees Declination and take note of the angular distance traveled.  Did RA move 90 degrees?

Started at 8h 6m ends at 14h 00m -> 6h -> 90° -> OK

 

ISSUE: DEC AXIS!

Does anyone have got a hint?


Frank
 

EDIT: Found the Issue! My Dec is 16teeth pulley... looks like I got the false Pulley... but honestly.. better this way :D