Skywatcher EQ3-2 BluePill STM32 Goto moves way to much #EQ3


On Sun, May 30, 2021 at 03:56 PM, Frank wrote:
I labeled the cables wrong.
It's probably happened to all of us at one time or another--can make for a wild ride!


HI all,

today I worked on my OnStep again and I am so sorry... I labeled the cables wrong... :-( last time I checked the cable twice. Sometime its better to step back and have a look some time later.

The OnStep works... I am struggling with the accuracy, but I first buy new belts, because I think it should be more tight to prevent slipping. After that I will re read the wiki.

Thank you all!

John Petterson

Frank,  That information in the FAQ will help sort out the directional movements to get that right, and then to check on the amount of movement.   You should also read the section in the Wiki about the Bluepill and TMC drivers ( and scroll down to stepper drivers), and check the jumpers that you have installed.  Those should set the board up to allow changing the microstep rates.

Howard Dutton

Follow the second item in the Frequently Asked Questions.


Hello and gooooood evening from Germany ;-)

First of all, again! Thank you for this project. I have got a Skywatcher 150/750 Newtonian telescope on a EQ3-2 mount. I moved from a MKS Gen L to BluePill STM board. But now I am facing an issue, which I can not explain.

I am currently in testing stage and my mount is pointing to Polaris and so on. I uploaded my site coordinates using an old android phone with OnStep app on it and synced the time.

On my iPhone with different apps like Stellarium or sky safari on it I can control the telescope over wifi. The issue now if I am doing a goto to Kochab or to Capella for testing, the telescope moves to much. For example the degree from Polaris to capella should be for example 40 degree to west. The telescope moves to west but it points down, lets say it moves 200 degree. 

My hardware setup for OnStep is:
BluePill Board
TMC2130 SPI (bigtreetech)

With the MKS Board it was working and I don't have got any clue which I made different.

My XLSX Calculations:

Attached also my config.

Can someone have a look on this and help me, please?

Maybe the


Setting does not work on the bluepill board?

Thank you :-)