Adafruit Capacitive Touch Sensor Breakouts Created by Bill Earl Last updated on 2016-09-28 07:23:37 PM UTC
Adafruit Capacitive Touch Sensor BreakoutsCreated by Bill Earl
Last updated on 2016-09-28 07:23:37 PM UTC
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Guide Contents
Guide ContentsOverview
MomentaryToggle5-Pad Momentary
Assembly and WiringInstalling the Headers:Position the header stripsPosition the breakoutAnd Solder
Wiring for Toggle and MomentaryToggle OperationMomentary Operation
Other Options:LED ControlSpeed vs. Power (Momentary Only)Timer (Toggle Only)Connecting to your Circuit.Simple Motor Control
Wiring for 5-pad MomentaryAdding Custom Touch Pads
Wire, Thread, Foil, Fabric, PaintConnections:Sensor Pads
Build a Touch Control PanelDesign your panelCut the touch-padsAttach the touch-padsAttach the WiresAdjust the WiresInstall the PanelAnd TestConnect to your Circuit
DownloadsFiles
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AT42QT1010 BreakoutAT42QT1012 BreakoutAT42QT1070
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Overview
These breakout boards are a simple way to add capacitive touch to your project. Justpower with 1.8 to 5.5VDC and touch the pad to activate the sensor. These touch switchesinterface 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, thesensor detects the change in capacitance and activates the switch. Custom sense-padscan be made form nearly any conductive material and these sensors can detect touchthrough thin layers of non-conductive materials such as glass, plastic, fabric or even wood.
The breakouts come in three styles:
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Momentary
This sensor has a built-in sense-pad and is active for as long asthe sensor area is touched.
The sense-pad can be extendedwith wire and almost anyconductive material.
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Toggle
This sensor also has a built-insense-pad. It becomes activewhen touched and remains activeuntil it is touched again.
As with the momentary sensor,the sense-pad can be extendedwith wire and almost anyconductive material.
5-Pad Momentary
This version combines 5momentary switches into one
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breakout. There are 5 pins forattaching wires to up to 5external sensor pads.
We also have a new 12-Keyversion with it's own tutorial overhere! (http://adafru.it/dKH)
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Assembly and WiringThese breakouts come fully assembled. For use in a breadboard, you may want to take acouple minutes to install the included header strips:
Installing the Headers:
Install the headers by following these 3 easy steps. The photographs below show one ofeach sensor type.
Position the headerstrips
Plug them long-pins down into abreadboard to stabilize them forsoldering.
Position thebreakout
Place the breakout board overthe header pins.
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And Solder
Solder each pin for solidelectrical contact.
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Wiring for Toggle and Momentary
These two breakouts are very similar and can be powered by anything from 1.8V to 5.5VDC. Simply connect Ground to GND and the positive voltage to VDD. The standalonesensors are fully functional without further connections.
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Toggle Operation
The Toggle version of the sensorturns on when you touch it once,then turns off when you touch itagain. The on-board LEDindicates the state of the switch.
MomentaryOperation
The momentary touch sensorworks just like a momentaryswitch. It is on when you touch itand off when you move away.The on-board LED indicates the
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state of the switch.
Other Options:These sensors have several jumper configurable operating modes as described below:
LED Control
The led indicators can bedisabled for ultra-low powerapplications. To disable the LED,simply cut the jumper betweenthe pads where indicated on theback of the breakout board.
With the jumper cut, the LED canbe controlled externally via theLED pin on the header.
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Speed vs. Power(Momentary Only)
The Momentary version can beconfigured for "Fast" mode(default) or low-power mode.Fast mode requires 0.5mA. LowPower mode requires just 50uA.To switch between the two, cutthe jumper on one side of the"mode" pads and bridge the otherside with a drop of solder.
Timer (Toggle Only)
By default, the toggle sensor isconfigured for infinte time-out. itwill stay on until you touch thesensor to turn it off. It alsosupports a configurable time-outto turn off the outputautomatically after a delay. Toselect this mode, cut the 'TIMER'jumper and connect a resistor &capacitor to the TIME pin. For acircuit diagram andresistor/capacitor calculations,see page 13 of thedatasheet (http://adafru.it/cgW).
You can also just connect TIMEto Vdd and the chip will turn offapprox 15 minutes after beingturned on. Connect TIME to OUTand the chip will time-out approxone hour after being turned on.
Connecting to your Circuit.
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The outputs of these touch switches are 'active high'. Use them like a positive logic signal,or a pushbutton that shorts to VCC.
Simple MotorControl
You can use it just like apushbutton or logic signal with atransistor or MOSFET to drivehigh-current loads like a DCmotor.
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Wiring for 5-pad Momentary
The 5-pin momentary breakout can be powered with anything from 1.8V to 5.5VDC. Justconnect ground to GND and the positive voltage to VDD. This sensor does not have built-intouch pads, but you can create your own pads in any size or shape from wire, foil or anyother 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 chiponly 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 owncustom capacitive touch panel!
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Adding Custom Touch PadsCustom touch pads are easy to make. You can use almost any conductive material:
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Wire, Thread, Foil,Fabric, Paint
If it will conduct electricity, it willwork as a touch sensor!
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Connections:
The Toggle and Momentaryboards have a solder holelocated just below the sensor padfor attaching a wire to an externalsensor.
The 5-pad breakout has pinsnumbered 0-4 on the left side ofthe board.
Sensor Pads
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Attach the connecting wire to anyconductive object or surface.That surface will become touchsensitive. Larger surfaces tend tobe more sensitive. You will beable to sense through fabric,plastic glass and many othernon-conductive materials.
Note that the wire will be touchsensitive too! Be sure to routeany connecting wires away fromareas where they might create anaccidental touch input.
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Build a Touch Control Panel
Capacitive touch sensors are a great way to add external controls to a waterproofenclosure. There is no need to drill holes or worry about gaskets and O-rings. Thesesensors will detect your touch right through the plastic case!
Design your panel
You can draw it by hand, or withyour favorite drawing tool andprint it on some heavy card-stock.
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Cut the touch-pads
Cut pads from copper tape.About 1/2" square is a good sizefor buttons on a touch-pad.
Attach the touch-pads
Peel the release paper from theback of the copper tape and stickthe touch-pads to be back of thepanel so that they align with thebuttons on the front.
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Attach the Wires
Solder wires to the copper touch-pads. For this example, I used a6-conductor 0.1" socketcable (http://adafru.it/206) withone end cut off to simplifyconnections to the breakout.
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Adjust the Wires
Bend the wires away from thepanel. The wires will be touch-sensitive too. To preventaccidental false touches, we wantto keep them away from thepanel surface.
Install the Panel
Tape the panel to the inside ofthe polycarbonate cover usingclear packing tape.
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And Test
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Connect the cable to thebreakout. Power it up and testyour control panel. Touchingeach button should cause adifferent LED to light up.
Connect to yourCircuit
The output signals are 'activelow', so they can replace any
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pushbutton that shorts to ground- such as the buttons on the RGBLCD shield. You can leave off thebuttons and solder directly to thecircled pads, or (if your shield isalready built), just 'tack-solder'the wires to the legs of thebuttons.
When you put it all together, you will have a completely sealed, touch sensitive controlpanel!
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Downloads
FilesAT42QT1070 Datasheet (http://adafru.it/rha)AT42QT1010 Datasheet (http://adafru.it/rhb)AT42QT1012 Datasheet (http://adafru.it/rhc)Objects for all in the Adafruit Fritzing Library (http://adafru.it/aP3)EagleCAD PCB files for all three in GitHub (http://adafru.it/rDr)
AT42QT1010 Breakout
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AT42QT1012 Breakout
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AT42QT1070
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