SKR V1.4 Turbo Fans / Serial Ports

I’m using an SKR V1.4 turbo for my lowrider 3 build and have found the Marlin 2.1.1 source/config on the V1 engineering github and think I’ve got it under control, but I’ve got a couple of questions about setting it up.
I haven’t got it up and running yet so can’t actually test anything.

  1. The SKR 1.4 only has a single PWM fan output, normally FAN0 (part cooling). I’ve enabled USE_CONTROLLER_FAN as it would be nice to have the fan switch on/off to cool the stepper drivers as required.
    I’ve added “#define FAN_PIN -1” in configuration_adv.h to remove the existing FAN0 definition in the pins.h file (I hope/think).
    I set “#define CONTROLLER_FAN_PIN P2_03” (the pin that was FAN0).
    Is that all I need to do, will it work, and will the controller fan now be on the FAN0 connector?

  2. I’m going to mount a raspberry pi in with the controller board, and have it as a host with a web server using something like cncjs. I also want to have the TFT touch screen on the machine.
    I guess I can connect the Pi via USB, but it would be nice to connect the UART pins to the pi directly to keep the cable management all internal to the enclosure and looking neat.
    The BTT docs show to connect a Pi to the RX/TX pins that the TFT screen will be using. I cant seem to find any other serial pins on the board. Is there any? How do you configure them?


I find the whole ‘fan’ thing quite confusing, however, I think what you have done sounds right.

There are other UART’s on the SKR V1.4. I think UART3 is available because you can configure a ESP-01s wifi module to UART3 to give the SKR wireless. The other UARTS are already in use or reserved for other functions.
So if you wanted to use UART3 for serial from the Pi I guess that would work. You might want to check your Marlin version has a define for 3 serial ports else you will lose the ability to connect via USB (serial_port_1 = 0 //for tft screen, serial_port_2 = 3 // for Pi and serial_port_3 = -1 //for USB)

Thanks. I love his videos on Youtube, always does a good job of explaining it for me. Once my Pi shows up I’ll try it out.

I’m not so sure the fan thing will work anyway. I think the Z steppers are always on (so it doesn’t drop down), which I guess means the fans will be on all the time as well. Once I get some fans I’ll try that out as well.

Seen some people with 12V power supply just wire up their 12V fan(s) to power (using WAGO connectors or similar), not bother with SKR Fan pins, so the fans are always running when the SKR board is powered up. One less thing to orchestrate starting and stopping in sync with the cut/carve job.

On my 3D printer I have setup USE_CONTROLLER_FAN, and the fans turn on automatically when I start printing or activate the steppers by moving an axis. They then turn off automatically when the steppers turn off after its been idle for a minute or so.

On the lowrider I think the Z axis steppers are probably always active, so the fans will probably be always on as well.