LCD_I2C

Simple Arduino library for controlling Hitachi HS44780 device via an 8 bit I2C/GPIO PCF85743.

Combined Hitachi LCD modules controlled by a PCF8574 device are commonly available online. The I2C/GPIO expander comes on a daughterboard that is mounted on the back of the main unit. The IO expander is an 8 bit device and so the screen is operated in 4 bit mode.

The PCF8574 daughterboard to Hitachi screen mapping is:

0. Register Select
1. Read/Write
2. Enable (Clock)
3. LIGHT
4. DATA4
5. DATA5
6. DATA6
7. DATA7

I have aimed to make the library as small and simple as possible. It is derived with information from some other libraries and tracing the circuitry of the daughterboard. I could find no libraries that worked out of the box for this specific board.

Feel free to copy and modify this library at will.

See also:

• https://en.wikipedia.org/wiki/Hitachi_HD44780_LCD_controller
• http://pdf1.alldatasheet.com/datasheet-pdf/view/18212/PHILIPS/PCF8574.html