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Hello from a newbie (onstep)


Ken Hunter
 

Hello guys,

I am just jumping into the fray and have jumped into the water feet first. I have been reading some of the many earlier posts mentioning "BluePill" etc and see that there have been many small and major changes over the months. I am an old guy and probably don't have time to read and analyze all the posts to figure out what is the current recommended configuration and list of parts to have the best chance of having a successful build. I am very competent in design and construction of electronic prototype devices so I do not anticipate any problems there. I have been playing with an Arduino UNO, making simple sketches etc to flash leds, operate steppers etc... nothing great but learning to recognize my mistakes when I make them again (That's called experience!).

One thing I am having a problem wrapping my head around is getting things to talk to each other. I am familiar with Stellarium operation on my PC as a stand alone program and have success using EzPushTo but having lived on observatory grounds for several years, I want GOTO for my 10 inch Apertura scope. I have steppers mounted for AZ, EL and Focus and can make them move with the UNO.  I was recently given an Android cell phone so I downloaded the Stellarium Mobile Plus APP. Tomorrow I will try to connect to my UNO +HC05 Bluetooth and gain more experience in making mistakes. Life goes on in spite of Covid and I try to learn more each day.

So, help an old guy out... what do I really need to buy on Amazon (love the free next day shipping!) to keep from re-inventing the wheel and gaining too much experience? What is no longer needed from previous builds etc. Wish me luck.

Thanks,

Ken Hunter
kb7hunter@...


andrea tasselli
 

Hi Ken,

I'd suggest to order the kit from George Cushing and stop worrying whether you got everything you need. The standard BluePill as reported in the Wiki works fine just as it is described there (and the building instruction from Dave Schwartz). The only issue outstanding is the Blue Pill STM32F103C itself. If you can find one with 128 Kb you'll be fine. Not sure when and where the replacement board is going to be available but most likely earlier in the N.A. market then elsewhere.

Cheers

Andrea


Mike Ahner
 

George also sells another kit, the MiniPCB2 I think it. Recently, he posted a price reduction to $40 since he can't get STM32F103C8 or STM32F303 parts yet.

Someone posted a link to an ebay seller for the STMF303 RobotDyn replacement, however it was much more expensive at about $11 each, with free shipping in the US.

Whatever you decide, you'll have better luck using one of the current board designs found in the Wiki, since they all have been tested and OnStep is known to work.

Another option with minimal construction is a Fysetc S6, also in the Wiki section. It's mostly complete, you just add a shield and wire in your motors, etc.

-Mike


Mike Ahner
 

On Sun, Nov 22, 2020 at 12:30 PM, Mike Ahner wrote:
Whatever you decide, you'll have better luck using one of the current board designs found in the Wiki, since they all have been tested and OnStep is known to work.
Looking at it again, there are several that are nearly complete and ready to wire in motors and sensors. Take a look at the Wiki page and the various boards there.


Lloyd Simons
 

The wemos/cnc3 uses the Uno format but with an ESP32. Cheap and easy to use.


Ken Hunter
 

Hi Guys..
Thanks for the comments, I'll take them under advisement and check out those options.

How do I contact or find George? I don't see him listed in the Directory.
I may decide to use the Wemos/cnc3 scenario as that is very close to the current setup I have been using on my breadboard (UNO and cncV3 shield).
I also have 2 Nunchucks that I have been playing with so it looks interesting to see if I can make everything play nice together.

I'm sure I'll be back with more questions... Keep safe!

Ken


Hemendra Rawat
 


On Sun, Nov 22, 2020, 3:49 PM Ken Hunter <kb7hunter@...> wrote:
Hi Guys..
Thanks for the comments, I'll take them under advisement and check out those options.

How do I contact or find George? I don't see him listed in the Directory.
I may decide to use the Wemos/cnc3 scenario as that is very close to the current setup I have been using on my breadboard (UNO and cncV3 shield).
I also have 2 Nunchucks that I have been playing with so it looks interesting to see if I can make everything play nice together.

I'm sure I'll be back with more questions... Keep safe!

Ken


Khalid Baheyeldin
 

Ken,

Each board has its features and provisos.
So read the Wiki on each of them before you buy ...

For example, the 3D printer boards (MKS Gen-L, FYSETC S6) and the CNC board (R32/CNCv3),
are not wired the same way as dedicated OnStep boards (Blue Pill, MiniPCB, MaxPCB), and
therefore the former will work fully only with two drivers (TMC2130 or TMC5160), while the
latter support more drivers (LV8729, S109).

The 3D printer boards have additional things like heaters, thermometers, ...etc, in case you
need them. They are also easier to get, and require less parts to be procured and minimal
soldering (not that this is a limitation in your case).

Here is a video I made today showing how easy it is to get a basic OnStep setup with the S6:

https://www.youtube.com/watch?v=AhEA3TjKxpM


Ken Hunter
 

Hello Khalid...

Thanks for the info even though I am fast approaching info overload.

Such a steep learning curve for something I thought would be an easy solution.
I am not familiar with the (MKS Gen-L, FYSETC S6 and Blue Pill, MiniPCB, MaxPCB)
I believe the CNC board (R32/CNCv3)  is the one that I am using with my UNO.
My hardware situation is NEMA 17 steppers on Alt and AZ axis, working through
homemade gearboxes, 40:1 on AZ and 60:1 on the EL axis. The final gearing is
unknown as the gearboxes drive large wooden disks with timing belts. Testing the
AZ axis with the UNO and cncV3, I need 269,550 steps to complete a 360 degree
rotation that takes approximately 3-1/2 minutes to complete. Math is not my strong
point but I think that is about 748.75 steps per degree and is the highest speed that
I can run the stepper and remain reliable in full step mode with the current setup..

Could that be reasonable or should I try for some different "fast" speed? The gear
reductions were made with on-hand gears and I don't mind waiting for a 2-3 minute 
GOTO when working in an area of the sky. It takes me much longer to find objects
in PushTo mode LOL

All help is very much appreciated so, thanks again!

Ken


Ken Hunter
 

Just found these on Amazon... https://www.amazon.com/s?k=STM32F103C&ref=nb_sb_noss
Is this the "BluePill" we are looking for?

Is the "wemos/cnc3"  mentioned earlier a replacement, another way, or something to be avoided
because of lack of PCB, support etc?

Caution: Blind man feeling his way in the dark!

Ken


Ken Hunter
 

Ummm... Reading the comment/reviews reveals that these are NOT the STM32 chips... They are different
clones that are sub-par and probably not usable in this project.

Sorry for the wasted bandwidth.

Ken


JOAN
 

Hi Khalid!
I use a MKS board with DRV8825 .
According to you comment:

For example, the 3D printer boards (MKS Gen-L, FYSETC S6) and the CNC board (R32/CNCv3),
are not wired the same way as dedicated OnStep boards (Blue Pill, MiniPCB, MaxPCB), and
therefore the former will work fully only with two drivers (TMC2130 or TMC5160), while the
latter support more drivers (LV8729, S109).

Will I get problems with th drivers I use?

Thanks for you support. You are great!
Rgds,
Joan Bertran


Howard Dutton
 

On Mon, Nov 23, 2020 at 02:08 AM, Ken Hunter wrote:
Is the "wemos/cnc3"  mentioned earlier a replacement, another way, or something to be avoided
because of lack of PCB, support etc?
Something to be avoided?  Not at all probably the way to go for you given you already have the CNCV3.

What stepper drivers do you have and "is about 748.75 steps per degree" based on full step mode?


Howard Dutton
 
Edited

On Mon, Nov 23, 2020 at 03:26 AM, JOAN wrote:
I use a MKS board with DRV8825 .
DRV8825's can often be really poor performers and so are not generally recommended.  Like most rules there are occasional exceptions (as in... I already have them and they work or using for focuser tin-can motor.)

According to you comment:

For example, the 3D printer boards (MKS Gen-L, FYSETC S6) and the CNC board (R32/CNCv3),
are not wired the same way as dedicated OnStep boards (Blue Pill, MiniPCB, MaxPCB), and
therefore the former will work fully only with two drivers (TMC2130 or TMC5160), while the
latter support more drivers (LV8729, S109).

Will I get problems with th drivers I use?
  • All supported 3D printer/CNCV3 boards provide shunts under the drivers to manually configure any micro-step mode you like for traditional StepStick drivers (LV8729, S109, etc.)  The slow Mega2560 based MKS Gen-L boards will be limited in goto speed with this kind of setup though since there is no ability to change the micro-step mode from within OnStep.
  • Most of our purpose designed OnStep boards (Bluepill, Mini2, Max2) allow the processor to do that same micro-step mode configuration.  They all have faster processors than the Mega2560 but they also allow changing the micro-step mode from within OnStep for fast gotos regardless.
  • Some 3D printer boards (S6, Mks Gen-L v2.0 v2.1) can also be configured for an SPI bus interface to the stepper drivers (so SPI controlled TMC2130 and 5160 drivers can plug right in and work.)  This allows changing the micro-step mode from within OnStep for fast gotos.
  • All of our purpose designed OnStep boards (Bluepill, Mini2, Max2, Max3) can be configured for an SPI bus interface to the stepper drivers (so SPI controlled TMC2130 and 5160 drivers can plug right in and work.)  They all have faster processors than the Mega2560 but they also allow changing the micro-step mode from within OnStep for fast gotos regardless.
There are "tricks" that would allow one to work around the MKS Gen-L limitations WRT to using mode switching with traditional StepStick drivers, like the LV8729 etc, it requires a little soldering (jumper wires or bridging driver mode control pins) and an understanding of how things work though... so I don't know of anyone who's actually done it.


Ken Hunter
 

Hello Howard...

Yes, the ~750 steps per degree is what I get in FullStep with my NEMA 17's and 8225 drivers on the cncV3/UNO configuration.
Using AccelStepper acceleration I can get a bit more speed but torque and stalling/skipping is the result. I am using a 13.6 volt 35 amp supply so the power is "STIFF" and not an issue on the bench. Yes, I already have the UNO/cncV3, 8225's etc and have learned a lot during this Covid learning period so not a wasted effort or expense for me. If it's better to go another route, I will just change directions and chalk up the UNO/cncV3 to an Arduino programming and learning experience and move on even though I do have the parts on the way for the wemos/cncV3 as well as the SHC boards that I should be able to use whichever way I eventually go. For me, this is an exercise in design, construction and gaining a better understanding of the computing and PID process. I have spent several years living on observatory grounds so observing in the cold at objects I've seen with scope apertures measured in meters is not all that important LOL...

One thing I might suggest... As a newbie coming into the onstep world it took me a long time to realize that all the boards mentioned on the right side of the page were "alternate" ways that have been used to produce the onstep system and each way was an individual solution. I'm not sure how a better explanation of this could be presented but there was major confusion for me until the lights were switched on and I saw that these were different routes to the same result.

Safely isolated at home, soaking up info and trying to make sense of it all..

Ken


Ken Hunter
 

Another question...

I have ordered some SHC boards and the parts needed to complete 2 SHC's. 5 boards should be on the way in a few days. I do not anticipate that I will need to use more than 2 of them. Is there a way to offer the extra boards and parts to folks on the onstep group and also perhaps see if other folks are having extra boards etc. to offer also? For instance when I ordered the RJ connectors, I opted to get the bags of 50 items as the price difference was minimal on Amazon. I WILL have extras of these for sure LOL...

Why buy 5 for a dollar when you can get 50 for 2 dollars?

Ken


Khalid Baheyeldin
 

Ken,

This is the page for the S6, which has 'the works' and reasonably fast,
specially with the SPI drivers (TMC2130 or TMC5160, the latter is more
expensive, but has much less heat, and more current for larger motors).

And this is the page for the W32 + CNC V3. If you already have the shield,
then the W32 is very cheap, and you can get a controller quickly, get all
the mechanical part sorted and then test with it. If it is adequate (no reason
it won't be so), then stay with it. Just don't use the DRV8825 unless you
are doing purely visual. If you want astrophotography, then use the low
cost LV8729, and be done with it.

You can always scrap what you have and start anew with another controller
without having sunk a lot of money in the electronics part.


Khalid Baheyeldin
 

On Mon, Nov 23, 2020 at 06:26 AM, JOAN wrote:
I use a MKS board with DRV8825 .
According to you comment:

For example, the 3D printer boards (MKS Gen-L, FYSETC S6) and the CNC board (R32/CNCv3),
are not wired the same way as dedicated OnStep boards (Blue Pill, MiniPCB, MaxPCB), and
therefore the former will work fully only with two drivers (TMC2130 or TMC5160), while the
latter support more drivers (LV8729, S109).

Will I get problems with th drivers I use?
Joan,

From what I recall, you are doing visual observing, and not astrophotography? Right?
In that case, the DRV8825 may not be much of a hindrance. It will noisy and has
some vibration, but that is tolerable when doing visual.

If you want to do imaging with the MKS Gen-L, then just replace the DRV8825 with either
a TMC2130 or TMC5160, and you are good, as long as you don't mind the slower slewing.


Ken Hunter
 

Well, I have ordered everything I don't already have for the Wemos/cncV3 and parts are showing up already.
The Wiki say's:

***********************************************

WeMos R32 with CNC V3 Shield:

*** It's up to you to understand the design, connection, limitations, and use of this device and its components, I accept no responsibility. ***

OnStep version 4.4a or later is required for this device.
************************************************

I have downloaded the latest OnStep-master and calculations files from github but I can't find the version 4.4
The current latest release seems to be 3.16.zip

What to do and where to go now?

Ken


Lloyd Simons
 

On https://github.com/hjd1964/OnStep Choose Master from the dropdown then click the green code button and Download .zip.