Using BigTreeTech SKR Pico

[shishu94]

I'm thinking about using this project with the SKR Pico board.
https://github.com/bigtreetech/SKR-Pico
It is a RP2040 based board initially intended for klipper in the 3D printing community.
It has 4 stepper motor drivers, power regulation, PWM ports, and many other things and can be found relatively cheap.
Is there any attempt to build this driver for it ?

[Update] I noticed a mapping for it already so never mind the question.

[terjeio]

If you get around to to try/use this map please report back as I have not verified it myself.

[terjeio]

But that is normal, drivers are connected through UART not SPI.

Tuning sensoless homing is tricky, more so with the UART versions of the TMC drivers. Have a look at the driver datasheet...

Still can't understand why laser grbl and lightburn can't connect.

IIRC Lasergrbl assumes that it connects to a controller that has exactly the same settings as legacy Grbl or it crashes. It is nearly two years since I last patched it (v3.0.22) and I have no idea if this has changed in later versions. A quick test I did just now with the patched version resulted in it freezing with the RP2040 and working (at least it seems so) with ESP32 and STM32F756 controllers I happen to have on my desk. Odd.

Oh, I just tested with the latest version - it works with STM32F756 and hangs with RP2040...

LaserBurn is known to work with grblHAL so again odd. Is there something special with the RP2040 USB stack/driver? I do not have a LaserBurn license so I am not able to try.

You may try compiling with a different compatibility level, but no sure this helps as Lasergrbl just freezes up for me (I have to terminate it from the task manager).

[shishu94]

I managed to test a few other things.

I checked that the Serial usb driver was not answering with a simple serial console.
So I recompiled with the uart serial Tx(0)/Rx(1) (disabling the USB serial) and plugged the board with a FTDI serial reader that I had laying around. Didn't mess with the compatibility level (it was at 0 by default anyway).

With that IOSender, LaserGRBL and Lightburn work out of the box. Could even run a laser cutting sequence with Lightburn for a more comprehensive test.
Will probably test on a generic Pico to check if I have the same behavior.

So I guess a problem is around the USB serial driver. For today I won't be able to test more but will definitely dig around that in the next days.

[shishu94]

Turn out that the connection with Lightburn and probably LaserGRBL too is the DTR flag.
Just enabling it in Lightburn was enough to make everything work.

Currently the only remaining bug I have to solve is the M4 command which does behave weirdly.
In the end appart from the connection issues that are just configurations, everything works quitte well.

[terjeio]

Currently the only remaining bug I have to solve is the M4 command which does behave weirdly.

It is possible a typo in the driver code can be the source of this, I have just commited a fix that may help. And thanks for the feedback, appreciated!

[brandonsherring]

Can I ask how you wired it up, I am having issues understanding the E0 spindle outputs and the cycle start and hold being on same pins. Di you use the btt pico.map or did you compile it yourseld? I am new to grblhal, been using klipper for years I decided to build a large format laser engraver for my first engraver.. Any assistance would be appreciated.