Auto or digital contrast control for graphic LCD?

tang · Joined: 12 Oct 2007 Posts: 41

Looking for a way to control LCD contrast automatically or by digital means, in other words, without any electro-mechanical devices like a pot.

Anything out there?

mattcro · Joined: 03 Oct 2007 Posts: 327 Location: Scotland

Depending on the LCD bias requirements, you can use a PWM output with an RC filter to provide a variable voltage, or you can try a "digitally controlled potentiometer". These connect to the micro via SPI or I2C bus and have, for example, a 10K total resistance and you can select any of 64 positions for the "wiper", so you can control the contrast in software. Some of these devices will remember the last setting and automatically return to this setting when they power up. Available from various manufacturers like Analog Devices and Maxim.