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.

Note: This product is a collaboration with danjuliodesigns. A portion of each sales goes back to them for product support and continued development.

Get Started with the SparkFun Touch Potentiometer Guide

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

Add lots of touch sensors to your next microcontroller project with this easy-to-use 8-channel capacitive touch sensor breakout board, starring the CAP1188. This chip can handle up to 8 individual touch pads, and has a very nice feature that makes it stand out for us: it will light up the 8 onboard LEDs when the matching touch sensor fires to help you debug your sensor setup.The CAP1188 has support for both I2C and SPI, so it easy to use with any microcontroller. If you are using I2C, you can select one of 5 addresses, for a total of 40 capacitive touch pads on one I2C 2-wire bus. Using this chip is a lot easier than doing the capacitive sensing with analog inputs: it handles all the filtering for you and can be configured for more/less sensitivity.Comes with a fully assembled board, and a stick of 0.1" header so you can plug it into a breadboard. For contacts, we suggest using copper foil, then solder a wire that connects from the foil pad to the breakout.Getting started is a breeze with our Arduino library and tutorial. You'll be up and running in a few minutes, and if you are using another microcontroller, its easy to port our code.

CAP1188 - 8-Key Capacitive Touch Sensor Breakout - I2C or SPI (1:35)

This breakout board is the simplest way to create a project with a single "toggle" capacitive touch sensor. No microcontroller is required here - just power with 1.8 to 5.5VDC and touch the pad to activate the sensor.This sensor is a toggle output type: touch-on then touch-off. That means that when a capacitive load is detected (e.g. a person touches the sensor-pad area) the red LED will alternate turning off and the output pin will go high or low, respectively. This sensor is good for a project where you want to activate something on the first touch, then deactivate it when touching again, like a switch. You can also solder a wire to the middle pad and create your own capacitive pad if the built-in one isn't suited to your project.If you want to save power, the LED can be disconnected from the output pin (cut the trace between the jumper marked as such). We designed this breakout to have infinite time-out. The chip does support having the sensor time-out, so for example, if something is turned on, it will eventually turn off on its own. If you'd like to use this mode, cut the TIMER jumper and then connect a resistor/capacitor to the TIME pin. Check the datasheet for how to calculate the TIME pin to match your desired timeout.Comes with a fully assembled board, and a small stick of 0.1" header so you can solder and plug it into a breadboard. For additional contacts, we suggest using copper foil, then solder a wire that connects from the foil pad to the breakout.The datasheet has many details on sensitivity, power usage, etc.

Standalone Toggle Capacitive Touch Sensor Breakout (11:10)

This breakout board is the simplest way to create a project with a single "momentary" capacitive touch sensor. No microcontroller is required here - just power with 1.8 to 5.5VDC and touch the pad to activate the sensor.When a capacitive load is detected (e.g. a person touches the sensor-pad area) the red LED lights up and the output pin goes high. You can also solder a wire to the middle pad and create your own capacitive pad if the built-in one isn't suited to your project.If you want to save power, the LED can be disconnected from the output pin (cut the trace between the jumper marked as such). We designed this breakout to have the more-responsive "fast mode" which draws about 0.5mA. If you need ultra-low (~50uA) power usage, the mode jumper can be cut on one side & soldered closed on the other to fix it into that mode. Check the datasheet for specific power usage measurements.Comes with a fully assembled board, and a small stick of 0.1" header so you can solder and plug it into a breadboard. For additional contacts, we suggest using copper foil, then solder a wire that connects from the foil pad to the breakout.The datasheet has many details on sensitivity, power usage, etc.

Standalone Momentary Capacitive Touch Sensor Breakout (11:10)

This is a breakout board for Freescale’s MPR121QR2. The MPR121 is a capacitive touch sensor controller driven by an I2C interface. The chip can control up to twelve individual electrodes, as well as a simulated thirteenth electrode. The MPR121 also features eight LED driving pins. When these pins are not configured as electrodes, they may be used to drive LEDs.

There a four jumpers on the bottom of the board, all of which are set (closed) by default. An address jumper ties the ADD pin to ground, meaning the default I2C address of the chip will be 0x5A. If you need to change the address of the chip (by shorting ADD to a different pin), make sure you open the jumper first. Jumpers also connect SDA, SCL and the interrupt pin to 10k pull-up resistors. If you don’t require the pull-up resistors you can open the jumpers by cutting the trace connecting them.

There is no regulation on the board, so the voltage supplied should be between 2.5 and 3.6VDC. The VREG pin is connected through a 0.1uF capacitor to ground, which means, unless you modify the board, you can’t operate the MPR121 in low-supply voltage mode (1.71-2.75VDC).

This knit conductive fabric is plated with real Silver and super luxe! Use small pieces on the tips of gloves or in any soft circuit situation where you need a bit of stretch. This highly conductive fabric has a resistance of less than 1 ohm per foot in any direction across the textile. It can be used to make soft keypads and capacitive touch sensors, as well as soft "squeeze" switches. Great for use with FLORA.Sold as a 20cm x 20cm piece (minimum dimension)Use a dry iron on medium. Dry cleaning recommended. Do not use steam! Discoloration can occur.

Knit Conductive Fabric - Silver 20cm square (11:35)