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Sensor placement and partially constructed Labyrinth with some conductive rails and LEDs sewn in place.

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memset in c++

memset(array,0,sizeof(array));

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Labyrinth Prototype Construction. 

Clockwise from top left: button hole sewing for threading conductive paths through; making black piping as labyrinth walls, partially sewn and pinned labyrinth

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According to Arduino’s CapacitiveSensor library a medium to high resistor s required between the send and receive pin and a small capacitor (20-400pf) in parallel with the body helps stabilise the readings.

This sewing method involves sewing conductive paths under each flap of the fabric binding. A square of conductive material ( i.e. the conductive sensor) is sewn to the outside of one end of of the binding, stitching each side in place to make contact with each of the conducive trace paths. 

At the other end the resistor and capacitors are attached. The photos above show the resistor and capacitor layout. The component legs are curled and then stitched in place.

The left leg of the resistor needs to be sewn to the send pin. The second leg, attached to one leg of the capacitor and one conductive path needs to be sewn to the receive pin. The other leg of the capacitor is stitched to the second conductive path.

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Working out the labyrinth construction

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Labyrinth code test on Lilypad with 5 sensors.

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Fabric glues as insulators

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“Unwanted and unexpected capacitance in a circuit is called stray capacitance.”

”Even though there is no capacitance the formation can act like a capacitor.”

Minimise capacitance (e.g. by shortening the leads of thru hole components)

“Stray capacitance is cancellable at high frequencies and negligible at low frequencies.”

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This was a quick test of an LED Matrix. The matrix’ positive rows and negative columns are constructed with conductive tape, wrapped in cotton binding. At each intersection the positive petal of an lED is sewn to the positive rail, with the ground to the negative  It is important both rails do not connect. Only one ground and one positive rail of the matrix are wired in this circuit. The led where both rails cross turns on when the capacitive sensor is touched and off when untouched. The matrix is one big giant sensor.

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Tag V1.0  lands of light LED sequence test with play and reset buttons

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Fabric breakout boards under various stages of construction a) with conductive tape and b) with conductive tape wrapped in binding along with snap connectors attached with a snap plyers.

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Troubleshooting the fading issue in the serial monitor.

With: long brightnessIn = map(onProgress, 0, FADE_PERIOD, 0, 255) long brightnessOut = - map(onProgress, 0, FADE_PERIOD, 0, 255)

The brightness in value and brightness out value never reaches 255 or 0.