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AnalogWrite creates a PWM when value is 255 #388

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jpcornil-git opened this issue Oct 25, 2024 · 1 comment

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topic: code type: imperfection

jpcornil-git commented Oct 25, 2024

On legacy arduino platforms, when analogWrite value is 255, you get a DC/HIGH output (aliased to digitalWrite HIGH), see:

https://github.com/arduino/ArduinoCore-avr/blob/master/cores/arduino/wiring_analog.c#L110

While on UNO R4/renesas platform, 255 is converted to 255/256 and you get a PWM signal, see:
https://github.com/arduino/ArduinoCore-renesas/blob/main/cores/arduino/analog.cpp#L819

To match behavior, value should either be normalized to 255 ((1 << _writeResolution) - 1) or aliased to a digitalWrite as well

per1234 added type: imperfection topic: code labels

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jpcornil-git commented Oct 25, 2024

Workaround for this one is to use digitalWrite(pin, HIGH) (following a pinMode(pin, OUTPUT) to address #58) but it is not very clean

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