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Patch up issue for inverted complementary output on Backlight #24794

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Patch up issue for inverted complementary output on Backlight #24794

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4 changes: 2 additions & 2 deletions platforms/chibios/drivers/backlight_pwm.c
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Original file line number Diff line number Diff line change
Expand Up @@ -28,9 +28,9 @@
// Support for pins which are on TIM1_CH1N
#ifdef BACKLIGHT_PWM_COMPLEMENTARY_OUTPUT
# if BACKLIGHT_ON_STATE == 1
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@zvecr zvecr Jan 7, 2025 •
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Complementary output is inverted, so this configuration was intentional. Has this actually been validated to be not the case?

These backlight and rgb light bug fixes should also be submitted separately.

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Apparently the internal inversion happens only when both the normal and complementary outputs are enabled:
STM32F303 RM page 536
STM32F303 RM page 549

See also the code for the WS2812 PWM driver — it uses PWM_OUTPUT_ACTIVE_HIGH and PWM_COMPLEMENTARY_OUTPUT_ACTIVE_HIGH, and that driver would definitely break if an extra inversion would be applied.

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@HorrorTroll HorrorTroll Jan 8, 2025 •
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Complementary output is inverted, so this configuration was intentional. Has this actually been validated to be not the case?

Yes, just like sigprof explain. The inverted wasn't be the case, unless both the normal and complementary are in use.

These backlight and rgb light bug fixes should also be submitted separately.

Thanks, I'll try to split it out.

# define PWM_OUTPUT_MODE PWM_COMPLEMENTARY_OUTPUT_ACTIVE_LOW;
# else
# define PWM_OUTPUT_MODE PWM_COMPLEMENTARY_OUTPUT_ACTIVE_HIGH;
# else
# define PWM_OUTPUT_MODE PWM_COMPLEMENTARY_OUTPUT_ACTIVE_LOW;
# endif
#else
# if BACKLIGHT_ON_STATE == 1
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