Category: General LinuxCNC Questions
Good day all,
I wanted to share my experiences using the Raspberry Pi 5 to run my CNC machine and ask for some advice, as I am not sure where to go from here.
Please note, I am a novice at best!
To my surprise, I managed to set up LinuxCNC with EtherCAT to run my A6 servo motors that I got from StepperOnline. I am using the Probe Basic UI, and I love the setup so far. Big thanks to RodW for all the work and instructions on setting up EtherCAT.
I am also using an Arduino Mega connected to the Pi for general-purpose I/O—this also works great. (Using LinuxCNC_ArduinoConnector from:
github.com/AlexmagToast/LinuxCNC_ArduinoConnector) This will mainly be used for buttons and tool changer I/O, so latency is not an issue. An EtherCAT I/O module would be better, but they are rather pricey.
What I would like to do is add a step/dir interface for my Z-axis, as this is still driven by a closed-loop stepper motor (my X and Y axes are EtherCAT). I want to be able to run the motor at a maximum of 200 kHz step rates. In the future, I would like to add a second Z-axis as well.
What I have tried:
- Using the GPIO pins from the Pi, but this does not generate step rates fast enough to run the motor. This also causes some latency issues, as the step generation is now done on the Pi.
- I switched out the Pi 5 for a Pi 4 (since SPI is not supported on the Pi 5) and tried using the Remora SPI interface to run a BTT SKR 1.4 as an external step generator. However, this also had a maximum step frequency that was too low. Additionally, I would prefer to use the Pi 5 instead of the Pi 4.
I would also like to build a second machine using only stepper motors with a step/dir interface. My motor drivers accept a maximum of 200 kHz.
I am looking for a solution that will allow me to run LinuxCNC on a Pi 5 with external step generation around 200 kHz that is not too pricey.
Any advice on which direction I should go next would be greatly appreciated.
