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Is it reasonable to control LCD brightness and contrast directly with the PWM pins of an Arduino, or would it be advisable to use a capacitor/filter to get a constant analog voltage?

I assume human eyes can't respond at PWM frequencies, but is there any issues with the LCD electronics?

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You can use PWM but I'd definitely not risk sending it as raw PWM to the LCD - use a low pass RC network for sure. I guess the risks are not big but neither is the inclusion of a 1k resistor and a 10uF capacitor. Without the filter I can foresee some strange aliasing effects on the screen (unless the LCD has got a filter built-in but how would you know?).

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    \$\begingroup\$ A quick web search indicates your intuition is correct. It sort of worked for some people with some "shimmering" at some contrast levels. I did this once in a product and used a filter, can't remember if I tried it w/o or not, then went to the usual thermistor for automatic temperature compensation. \$\endgroup\$ Jun 11, 2014 at 11:49

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