# Just Veggin with an Arduino Beetbox

Bring Touch Control to the Arduino. Use interesting touch sensors like Carrots or Beets to make a “Beetbox”. In this project you will learn: * How to use the Cap Sense library to make Arduino responsive to touch * How adding a Wave Shield (and some root vegetables), you can make a “Beetbox”

### The Principles of Capacitive Touch Sensing

For the Beetbox we use three sense channels. To start we’ll implement one touch sense channel and activate an LED when Arduino senses touch. Wire up the circuit as shown in the Fritzing diagrams and photo’s. Get and Install the Capacitive Sense library for Arduino from here: http://goo.gl/EpSX0

### Step 3: Here’s How the Capacitor Sense Works

The Cap Sense circuit is made by the resistor between Arduino pins 6 and 9, and also the capacitance to ground on the Touch Sensor. When the CapacitiveSensor arduino library is asked to read the sensor value, pulses are Output on Pin 9 and Input into pin 6. The library routine measures the delay between when the pulses are transmitted and when they are received. The measured delay is proportional  to the Resistor value R and the Capacitance C. i.e.   Delay = R*C (strictly speaking there’s a scaling factor too depending on the voltage level you’re measuring from, but that’s just a detail for us). The Capacitance on the sensor varies as you bring your finger close to the sensor and as you touch it. Touching the sensor gives you the largest capacitance and the longest delay. In order to make the delay large enough to be detected by Arduino you need a large resistor e.g. 4.7Meg Ohms.
The Cap Sense circuit is made by the resistor between Arduino pins 6 and 9, and also the capacitance to ground on the Touch Sensor. When the CapacitiveSensor arduino library is asked to read the sensor value, pulses are Output on Pin 9 and Input into pin 6. The library routine measures the delay between when the pulses are transmitted and when they are received. The measured delay is proportional  to the Resistor value R and the Capacitance C. i.e.   Delay = R*C (strictly speaking there’s a scaling factor too depending on the voltage level you’re measuring from, but that’s just a detail for us). The Capacitance on the sensor varies as you bring your finger close to the sensor and as you touch it. Touching the sensor gives you the largest capacitance and the longest delay. In order to make the delay large enough to be detected by Arduino you need a large resistor e.g. 4.7Meg Ohms.

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