PWM fan not shutting off at 0% on BTT M8p board
Installed the BTT Manta M8p 1.1 board today, run through the config and its all set up. Trying to run an Arctic Cooling 4028 fan. Its PWM and connected to the correct socket on the board. I can control it fine so its all connected to the right pins and linked the 25khz part cooling fan cfg, but at 0% it still spins at 1100rpm which is the min value in the datasheet. But i want it to turn OFF at 0%.
I saw a section for the issue on the "connecting a 4028 fan" page of the RATOS setup guide but it says about using the enable_pin option in klipper. But when i go to use the pin (PB8) it gives the error: pin PB8 is an alias for 4p_fan_part_cooling_pin.
What do i need to add or edit to get it to turn the fan off when set to 0%?
printer.cfg attached. Thank you
7 Replies
that config doesn't have
enable_pin, upload the one you are having issues with
also did you wire the fan to have the ground pin connected to one of the heater ports negative terminal?like-goldOP•16mo ago
I did try with [fan] enable_pin: PB8 in the user overrides section and it said the error about already assigned. The m8p has dedicated 4 pin sockets, I used those rather than the work around solution for other boards. Do I need to pull the ground pin out and wire it into an unused pin?
yes, you need an addressable ground pin, the one in the 4 pin socket isn't addressable
like-goldOP•16mo ago
Ok thank you confirming. I guess klipper wasn't designed with usual 4 pin fans in mind!
it has nothing to do with klipper, the board doesn't allow those to be addressed
https://github.com/bigtreetech/Manta-M8P/blob/master/V1.0_V1.1/Hardware/BIGTREETECH%20MANTA%20M8P%20V1.1%20PinOut.png
see how the pin for your fan is just listed as
GND whereas the heater port is listed as PB5like-goldOP•16mo ago
Weird that btt did it that way but maybe this is an edge case they didn't consider. Anyway thank you, wired the gnd up to the unused heater pin and functions perfectly now. Thanks
It is yes. Server fans usually shut off with a 0% PWM signal (not to be confused with no signal). Arctic don't make server fans, they make pc fans, they act differently.
A sanyo denki on those 4-pin ports will stop spinning at 0% (depending on model it stops below 10 or 30%).
So in short: if you buy the right fan it acts like you'd expect it to.