MarlinFirmware/Marlin

[BUG] LASER_FEATURE inhibits CONTROLLERFAN_SPEED_ACTIVE setting

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#22,291 opened on Jul 3, 2021

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Bug: Confirmed !help wanted

Description

Did you test the latest bugfix-2.0.x code?

Yes, and the problem still exists.

Bug Description

I was using CONTROLLERFAN_SPEED_ACTIVE at 190 and worked fine until I activate LASER FEATURE. I noticed that controller fan was not working as it should, and I realized that CONTROLLERFAN_SPEED_ACTIVE needs to be at 255 to work . If I use any other value controller fan stops turning. I am using different pins to control controller fan and laser. To control the laser I am using the servo pin D6 (PWM 5V) on Trigorilla board.

Readings

  • LASER FEATURE disabled

PWM output 500Hz

M710 S50 - PWM duty cycle of 79% - approx 3,44V on fan terminals (not enough torque to start) M710 S150 - PWM duty cycle of 41% - approx 8,3V on fan terminals (it turns with reduced speed) M710 S190 - PWM duty cycle of 25% - approx 10V on fan terminals (it turns with reduced speed) M710 S220 - PWM duty cycle of 13% - approx 11,4V on fan terminals (it turns with reduced speed) M710 S254 - PWM duty cycle of 0% - approx 12,87V on fan terminals (it turns full power) M710 S255 - PWM duty cycle of 0% - approx 12,9V on fan terminals (it turns full power)

  • LASER FEATURE active

PWM output 2500Hz

M710 S50 - PWM duty cycle of 97% - approx 1,06V on fan terminals (not enough torque to start) M710 S150 - PWM duty cycle of 91,5% - approx 1,32V on fan terminals (not enough torque to start) M710 S190 - PWM duty cycle of 90% - approx 1,42V on fan terminals (not enough torque to start) M710 S220 - PWM duty cycle of 88% - approx 1,49V on fan terminals (not enough torque to start) M710 S254 - PWM duty cycle of 86% - approx 1,57V on fan terminals (not enough torque to start) M710 S255 - PWM duty cycle of 0% - approx 12,9V on fan terminals (it turns full power)

I realized that enabling LASER FEATURE PWM frequency changes. Maybe a scale error?

Bug Timeline

Issue was closed before being fixed on December 2020

Expected behavior

With or without LASER FEATURE function activated, controller fan should turn to the specified CONTROLLERFAN_SPEED_ACTIVE value.

Actual behavior

When activating LASER FEATURE controller fan only works if the CONTROLLERFAN_SPEED_ACTIVE value is 255.

Steps to Reproduce

  1. With LASER FEATURE disabled, change CONTROLLERFAN_SPEED_ACTIVE to 190.
  2. Test controller fan by moving any axis. It should work well.
  3. Now, activate LASER FEATURE and upload the changes to the printer.
  4. Test controller fan again. Fan doesn't turn.
  5. Change CONTROLLERFAN_SPEED_ACTIVE to 255 value. The controller fan starts turning.

Version of Marlin Firmware

Tested on FW 2.0.6.1, 2.0.7.1, 2.0.9, 2.0.9.1

Printer model

Anycubic I3 Mega S

Electronics

Stock motherboard

Add-ons

No response

Your Slicer

Cura

Host Software

No response

Additional information & file uploads

No response

Contributor guide

Tech stack
cpp
Domain
backend
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
C++ basicsMarlin firmware structurePWM conceptsUnderstanding of CONTROLLERFAN and LASER FEATURE
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
50
Research direction
Investigate the interaction between LASER FEATURE and CONTROLLERFAN in Marlin firmware. Focus on files such as `Marlin/src/feature/controllerfan.cpp` and `Marlin/src/feature/laser.cpp` to understand how enabling the laser feature changes PWM frequency and interrupts the fan speed setting. Review the discussion in comments 10-15 for specific clues about the root cause. Check the commit history for any prior attempts to fix this issue.