These breakout boards are a simple way to add capacitive touch to your project. Just power with 1.8 to 5.5VDC and touch the pad to activate the sensor. These touch switches interface easily to any project - with or without a microcontroller.
When a capacitive load (such as a human hand) is in close proximity to the sense-pad, the sensor detects the change in capacitance and activates the switch. Custom sense-pads can be made form nearly any conductive material and these sensors can detect touch through thin layers of non-conductive materials such as glass, plastic, fabric or even wood.
The breakouts come in three styles:
Assembly and Wiring
These breakouts come fully assembled. For use in a breadboard, you may want to take a couple minutes to install the included header strips:
Installing the Headers:
Install the headers by following these 3 easy steps. The photographs below show one of each sensor type.
Wiring for Toggle and Momentary
These two breakouts are very similar and can be powered by anything from 1.8V to 5.5V DC. Simply connect Ground to GND and the positive voltage to VDD. The standalone sensors are fully functional without further connections.
These sensors have several jumper configurable operating modes as described below:
LED ControlThe led indicators can be disabled for ultra-low power applications. To disable the LED, simply cut the jumper between the pads where indicated on the back of the breakout board.
With the jumper cut, the LED can be controlled externally via the LED pin on the header.
Speed vs. Power (Momentary Only)The Momentary version can be configured for "Fast" mode (default) or low-power mode. Fast mode requires 0.5mA. Low Power mode requires just 50uA. To switch between the two, cut the jumper on one side of the "mode" pads and bridge the other side with a drop of solder.
Timer (Toggle Only)
By default, the toggle sensor is configured for infinte time-out. it will stay on until you touch the sensor to turn it off. It also supports a configurable time-out to turn off the output automatically after a delay. To select this mode, cut the 'TIMER' jumper and connect a resistor & capacitor to the TIME pin. For a circuit diagram and resistor/capacitor calculations, see page 13 of the datasheet.
You can also just connect TIME to Vdd and the chip will turn off approx 15 minutes after being turned on. Connect TIME to OUT and the chip will time-out approx one hour after being turned on.
Connecting to your Circuit.
The outputs of these touch switches are 'active high'. Use them like a positive logic signal, or a pushbutton that shorts to VCC.
Wiring for 5-pad Momentary
The 5-pin momentary breakout can be powered with anything from 1.8V to 5.5VDC. Just connect ground to GND and the positive voltage to VDD. This sensor does not have built-in touch pads, but you can create your own pads in any size or shape from wire, foil or any other conductive material. Simply connect your touch-pads to each of the 5 sense pins. When you touch the pad, the corresponding LED on the other side will light up. The chip only detects one touch-pad at a time to prevent false readings.
5 touch inputs in one device makes this the perfect component for building your own custom capacitive touch panel!
Adding Custom Touch Pads
Custom touch pads are easy to make. You can use almost any conductive material:
Build a Touch Control Panel
Capacitive touch sensors are a great way to add external controls to a waterproof enclosure. There is no need to drill holes or worry about gaskets and O-rings. These sensors will detect your touch right through the plastic case!
When you put it all together, you will have a completely sealed, touch sensitive control panel!
This guide was first published on Jun 29, 2013. It was last
updated on Jun 29, 2013.