SparkFun Touch Potentiometer

The SparkFun Touch Potentiometer, or Touch Pot for short, is an intelligent linear capacitive touch sensor that implements potentiometer functionality with 256 positions. It can operate as a peripheral to a computer or embedded microcontroller or in a stand-alone capacity. The Touch Potentiometer provides both a dual-channel analog and PWM output for direct control of other circuitry. Configurable analog and PWM transfer functions support a wide variety of applications such as volume control and LED dimming.

The Touch Potentiometer is controlled by a Microchip PIC16F1829 8-bit micro-controller that provides the host interface, LED control, capacitive sense and peripheral control functions. A built-in low-dropout voltage regulator allows operation over a range of input voltages up to 12V and breadboard friendly connectors make it easy to play with. A desktop application has been created by our collaborator, Dan Julio, that communicates with the Touch Pot over a serial connection. From this utility app you can change configuration settings, alter LED behavior, calibrate the capacitive touch sensor, view current readings in jabber mode, and much more.

Features:

• Dual host interfaces: Logic-level serial and I2CTM
• Dual 8-bit 20 k-ohm 3-terminal digitally controlled variable resistor outputs
• PWM output
• 8 LED display with multiple display modes and intensity levels
• Option for interpolated (soft) changes between touches
• Configurable touch sensor parameters for a variety of PCB covers
• Easily configurable I2C address to allow multiple devices on one bus
• Configurable linear or non-linear PWM transfer function
• Configurable linear or simulated logarithmic variable resistor transfer function
• Variable resistor supports single- or dual-supply operation
• Simple register interface with jabber option
• Programmable power-on default operation
• Built-in calibration procedure
• User-accessible EEPROM data storage
• Built-in 5V LDO voltage regulator
• Through-hole and SMT connectors