I tried to illustrate my problem in the videos above, two of them show the weird movement and the other shows me clicking on the home button repeatedly.
- Marlin 1.1.8 or 2.0.0 (same problem in both)
- Robotdyn RAMPS 1.4
- 0.9 angle stepper motors
- DRV8825 drivers configured at 0.8V Vref
- Anet A2 Plus stock for all the rest
As far as I can see on the attached videos your homing movement is reversed. as per Marlin, the homing for X shall move towards the left side and for Y to the back of the printer.
That could occur when: cable connectors to stepper motors are reversed, or the motor is assembled the other way (you can set reverse direction in Marlin)
The other issue is steps/mm calibration need to be done see source below.
The high pitch in the video could also point that the drv8825 is shutting down the movement as it is overloaded.
please also check that for vref
Configuring Vref In order to measure Vref you first need to turn on your printer as you normally would. If you only connecct using USB, but not external power, you get a wrong reading.
You need to turn on your multimeter and set it at 2v. Put the red one on the potentiometer and the Black one on the Gnd pin. Both are marked on the images here.
Before starting this I read they come with a very high vref setting, and it is recommended to start around 0.5v Vref. After measuring mine, I can confirm they come with a very high initial setting. Mine both came at 1,65v or so! - Yours might be different, which just underlines the importance of doing this.
Contrary to normal potentiometer usage, the ones on most copies/clones of DRV8825 are lowered by turning clock-wise, so that is what we will do, to we hit 0,5v on each. - A quarter of a full turn lowered it to 0,7v, - after that it goes very, very rapidly down, so aim for the quarter of a turn + a tiny tad more. If you buy your DRV8825 directly from pololu.com the Potentiometer are dialed up by turning it clock-wise: