In a commercial product, would it be a good idea to control LCD contrast using a microcontroller?
The LCD is to be installed in a vehicle and is to withstand temperature changes. I am concerned if the temperature changes would cause the LCD to be become unreadable.
The microcontroller i am using to control LCD does not have a DAC so I will be using a digital pot or external DAC.
Best Answer
In most examples I've seen the contrast control line has been adjusted automatically by a thermistor: -
This picture came from here - it describes how the circuit works and shows its output compared to the typical theoretical requirements for a typical LCD.
You can of course use a micro but you'd be copying most of the circuit above, reading the analogue value into the micro thru an ADC pin then outputting possibly a PWM signal that can be low pass filtered then fed to the LCD. Can't see the need to over complicate it really. Stick with "simple". Simple is usually best!
Here's another page that uses the same circuit. Here is a computational tool that can help - slightly different circuit but the tool, I'd imagine, will give you values.