ST currently has two resistive touch screen controller devices available. This slide shows the STMPE811 which is a GPIO (general purpose input/output) port expander able to interface a main digital ASIC via the two-line bidirectional bus (I2C). The STMPE811 offers great flexibility, as each of the eight I/Os can be configured as input, output or specific functions. Four GPIOs can be assigned to read the 4-wire output of the screen and the other four can be configured as GPIOs or used as general purpose A/D converter channels. 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, 128 x 32 bit buffer and a programmable active window feature. The other controller, the STMPE610, is a GPIO port expander able to interface a main digital ASIC via the two-line bidirectional bus (I2C). The STMPE610 offers great flexibility, as each of the six I/Os 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 touch screen controller is built into the STMPE610. The touch screen controller is enhanced with a movement tracking algorithm to avoid excessive data, 128 x 32 bit buffer and a programmable active window feature. The main difference between this controller and the STMPE811 is the number of channels available. All other features are common, the three by three 16-lead QFN package, minus forty to eighty-five temperature range, low voltage capability and SPI and I2C interface, etc.