FTM Board Club
ON Semiconductor
Touch Switch Shield Evaluation Board

The touch switch shield evaluation board demonstrates the LC717A00AR which is a high-performance, low-cost capacitance-digital-converter LSI for electrostatic capacitive touch sensor, especially focused on usability. It has 8 channels capacitance-sensor input. The built-in logic circuit can detect the state (ON/OFF) of each input and output the result. This makes it ideal for various switch applications. The calibration function is automatically performed by the built-in logic circuit during power activation or whenever there are environmental changes. In addition, since initial settings of parameters, such as gain, are configured, LC717A00AR can operate in stand-alone mode when the recommended switch pattern is applied. Since LC717A00AR has a serial interface compatible with I2C and SPI bus, the PCA9655E is used to provide 16 bits of General Purpose parallel Input and Output (GPIO) expansion through the I2C-bus and SMBus, detecting outputs of the LC717A00AR's 8-input capacitance data and measuring it as 8-bit data.