Hi all,
I will be using a makita router/trimmer. And was looking at the grbl_spd board (https://jsharrison.ca/) so software can control speed etc of the trimmer via software.
Do you know if this can be done with the skr pro?
2 Likes
You should ask the maker of that board if they require GRBL. Marlin is perfectly capable of sending speed signals.
Thank you for asking this question, since I got to find out about the grbl_spd board. I didn’t know such a board existed.
I’m just a hobbyist with electronics, but my one concern about whether this board will work with the SKR Pro is the voltage of the PWM pin. I don’t own a SKR Pro, and I’m confused about some of the documentation for this board. I believe the microprocessor is 3.3V, yet many of the pins on the board are labeled as 5V. If it were me, I’d hook up a voltmeter to the PF9 pin (on Extension-1) and ground, and use an M42 g-code to set the PWM to 255. Look at the voltage. If it is near 5V, it is likely this board will work as is. If it is not 5V, then you will need to communicate with the board designer. You want to understand if the grbl-spd board is driven by voltage, or if it is driven by the duty cycle of the PWM signal.
If it turns out that voltage is important, and if the SKR Pro PWM pin is 3.3V, then it would be easy and cheap to add a level converter board to change the voltage. The SKR Pro has 5V pins available.
P.S It is my unconfirmed understanding that PF9 is an unused PWM pin. Alternately you could use PC9, which I know is a PWM pin since it is the designated laser PWM pin in the V1 maintained versions of Marlin. Assuming you are using V1 firmware, you can adjust the PWM value of PC9 with the M3 g-code.