External GH TMC2225 drivers with inpit shaping
Hi,
I sucessfully added input shaping to my old Prusa MK2.5S by using external board (VMOD) with GH TMC2225 Input Shaper stepstick drivers. Everything works fine up to speed 100mm/s bit when I go higher, the drivers go into Step Rate to high error.
Anyone has idea what is the maximum step rate in Hz that the prusa firmware is generating? Normally I should be able to go as far as 200mm/s but something is wrong. I see in source code that when frequency is more than 20kHz it devides it into 4 loops but have no idea how is the input to stepper drivers then. The GH Input Shaper deivers work correct only up to 48000 Hz so normally should be able to accept speed up to 480mm/s ( with 100steps/mm in Prusa firmware).
RE: External GH TMC2225 drivers with inpit shaping
I think you are confusing a number of things.
How it works with the GH stepper is explained here.
If you are working with a hardware input shaper such as an ADXL 345 and klipper,
a test signal of 1 to 130HZ is usually used.
But this does not apply to you.
RE:
I'm using hardware input shaper which is designed by GH company. They added extra chip on standard TMC2225 that is doing input shaping. This GH TMC2225 driver has a limitation of 48000 input step rate. And somehow prusa firmware manages to exceed it when printing with speed over 100mm/s. I can recognize this by very fast blinking diode on the driver and skipped steps. According to the GH documentation when it is blinking woth 4Hz it means that control board (Rambo Mini in this case) is feeding too high step rate.
Below 100mm/s it is working for me even on high acceleration (like 8000mm/s2). The results are awesome and it eliminates most ghosting for me. I can manage to print around 30-40% faster than normally. But can't go hogher than 100mm/s. Can only speed up by increasing acceleration.
Below links to stuff that I'm using:
- External driver board (discontinued): https://vmod.wordpress.com/prusa-mk2s-ext-driver-board-v2-3/
- GH TMC drivers with input shaping chip: https://gh-enterprise.com/en/3d-printer-controller/
The driver is physically soldered to rambo mini board step/dir outputs so prusa firmware controls how many steps / second goes to those drivers.