The STMPE811 is a GPIO (general purpose input/output) port expander from STMicroelectronics that can interface a main digital ASIC via the two-line bidirectional bus (I2C). It offers great flexibility, as each I/O can be configured as input, output or specific functions. The device has been designed with very low quiescent current and includes a wakeup feature for each I/O, to optimize the power consumption of the device. A 4-wire touchscreen controller is built into the STMPE811. The touchscreen controller is enhanced with a movement tracking algorithm (to avoid excessive data), a 128 x 32 bit buffer and programmable active window feature. It can be widely used in portable media players, game consoles, mobile phones and smartphones, GPS and other fields.