fix off-by-one in RP2040 PWM frequency setting #9398
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I think this makes sense, but I want to make sure you get 100% duty cycle if the duty cycle is set to 65535. Could you test that if you have not already. See #4192, which fixed some other (?) PWM off-by-one issues. I want to make sure this isn't a regression from that fix. |
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Here's data showing correct behavior at the extremes:
While I was at it I fixed the rounding issue that I had earlier addressed for Before
After
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dhalbert
approved these changes
Jul 3, 2024
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Setting of
TOPinpwmioon RP2040 is off by one. CurrentlyTOPis set tocommon_hal_mcu_processor_get_frequency() / frequencybut from datasheet p. 527 that is too big by one: "if TOP is programmed to 254, the counter will have a period of 255 cycles." Verified that with current code PWM period resulting from requested 2500000 Hz PWM frequency is too long at 408 ns. With these changes frequency is exactly 400 ns as requested.