Reading tachometer on duetwifi



  • Hi

    The fans that come with my prusa were quite annoyingly loud especially the one for the hotend.
    I have printed neccessary mounts to convert them to regular pc fans with tachometers.

    Just as a matter of course, I believe it would be a good idea for me to modify the firmware to monitor the tachmeters on the fans to ensure they are functioning
    throughout the print. The newer prusa mk3 does the same as people have had the hotend mount totally meltdown due to overheating caused by bits filament being trapped in the blades of the fan.

    Since I come from an arduino background, I have no idea what am doing.

    So in terms of making the ncessary firmware changes, where do I get the documentation I would need to get coding for such a arm processor?

    Also where is the eqivulent arduino eqivulent of the loop function in the firmware


  • administrators

    The tacho will only read correctly when the fan is operating at full speed, not if you are using PWM to reduce the speed. But if it is the hot end fan that you want to monitor, you are probably running that at full speed already.

    The firmware is already set up to read and display the RPM of one fan. Connect the tacho wire through a diode (1N4148 or similar should work) to pin PB6 on the expansion connector. The cathode of the diode (the end with the stripe) goes to the tacho wire.


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