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ledc_write max_duty bug #11049

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scrtrees opened this issue Mar 7, 2025 · 0 comments
Open

ledc_write max_duty bug #11049

scrtrees opened this issue Mar 7, 2025 · 0 comments
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@scrtrees
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scrtrees commented Mar 7, 2025

https://github.com/espressif/arduino-esp32/blame/9e2f75564127a9853f80f3eb637b264406cb2f30/cores/esp32/esp32-hal-ledc.c#L181

//Fixing if all bits in resolution is set = LEDC FULL ON
    uint32_t max_duty = (1 << bus->channel_resolution) - 1;

    if ((duty == max_duty) && (max_duty != 1)) {
      duty = max_duty + 1;

If a user want to set resolution as 5 and set duty 31/32, it should be failed.
Duty ratio should be like as below.

channel_resolution = 5, duty = 0 → duty ratio = 0/32
channel_resolution = 5, duty = 1 → duty ratio = 1/32
channel_resolution = 5, duty = 2 → duty ratio = 2/32
...
channel_resolution = 5, duty = 30 → duty ratio = 30/32
channel_resolution = 5, duty = 31 → duty ratio = 31/32
channel_resolution = 5, duty = 32 → duty ratio = 32/32

However, current code makes it like below.

channel_resolution = 5, duty = 31 → duty ratio = 32/32 -> WRONG RATIO
channel_resolution = 5, duty = 32 → duty ratio = 32/32

The code on top just need to be deleted.

@SuGlider SuGlider self-assigned this Mar 7, 2025
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