A weblog focused on interesting circuits, ideas, schematics and other information about microelectronics and microcontrollers.
I2C LCD back-pack
The I2C LCD Back-Pack is a small(ish) PCB that can be plugged onto the back of an LCD so that you may control it over an I2C bus.
The I2C Back-Pack is based on the 23017 from Microchip. The 23017 is a port expander with 16 GPIO ports. The ports can be either input or output, you can have week pull-ups, and an interrupt signal caused by changes on either 8 pin port making up the 16 pins.
In this project, 8 pins are used for the 8 bit interface for the LCD, 3 pins for the control signal to the LCD and the last five are free for button input (or other output if you want).