Detecting Small Capacitive Sensors Using the MCP6291 and PIC16F690 Devices

This application note is intended for hardware and firmware design engineers that need to accurately detect small capacitance values. It shows how to use a PICmicro microcontroller and minimal external circuitry to detect small capacitances. The design is based on an operational amplifier (op amp) integrator. A capacitive humidity sensor is used to illustrate this type of application, and alternatives and modifications to the design are briefly discussed.