Information Environments Equipment Listing and Support

Sensors - how they work

At the most basic level, sensors work by creating circuit which allows current to flow - the EZIO reads the resistance of the current to detect the activation level of a sensor.

In the case of an analogue sensor, this is returned as a resistance reading in the range 0 - 255, with 0 being no activation and 255 being full activation. For example, a touch sensor that is not being touched will return a reading of approx. 0 and depending on the amount of pressure being applied will return a value up to 255.

For digital sensors, they return a 0 or 1 reading based on whether the circuit is open or closed. NOTE: In contradiction to logic, the EZIO returns 0 when a digital sensor is activated and a 1 when deactivated - keep this in mind when developing.

Make your Own

Digital Touch Sensor

There are a number of touch strip scraps which can be wired to create a digital touch sensor. See diagram below for instructions.

Make Touch

Custom Pressure Mat

The image below shows how a pressure mat is made, use these principles to create on of your own. Place a thin piece of foam - with regular holes large enough to allow contact - between two sheets of conductive material, connect a wire to each conducting sheet. Connect one wire to the GND connector on the EZIO and the other to a DIGITAL IN and you now have a custom pressure mat. Be sure to pick a foam that is thin enough - this could alternately be any other non-conductive material, its main purpose being to separate the conductive sheets. When choosing a conductive material make sure it is something that does not crease easily, as this may cause permanent contact to be made.

Pressure sensor details

What we have available

[A = Analogue] [D = Digital]
[See equipment listing for exact numbers]

Touch [A] - in a variety of shapes and sizes - that responds to pressure/touch and returns a reading based on how much pressure is being applied.
Slide [A] - a strip sensor that responds to touch and returns a reading based on where on the strip pressure is applied.
Bend [A] - a strip sensor that returns a reading based on the direction and amount of bend applied.
Close [A] - that detect proximity of objects up to 1.75m.
Light [A] - that return a reading based on the level of light.
Tilt [A] - senses changes in the inclination of an object - single axis only.
GForce [A] - senses acceleration and deceleration of an object.
Turn [A] - a twist dial sensor that returns a reading based on the orientation of the dial.
Tap Tile [A] - as per Touch.
Passive IR [1xD 1xA] - responds to movement within an area.
Pressure Mat [D] - floor mat that responds to pressure.
Mercury Switch [D] - switch used to detect orientation/tilt.

Connecting Sensors to EZIO

Analogue Sensors

Analogue sensors all have 3 wires that connect to the EZIO, RED going to +5V, BLACK going to GND, and white going to A/D [See diagram in EZIO Setup]. If you need to connect more than 8 analogue sensors (the limit of the A/D inputs) and/or are only concerned with on/off readings, you can connect further analogue sensors to the DIGITAL IN connectors. This will provide you with an extra 10 inputs.

Digital Sensors

Digital sensors have 2 wires that connect to the EZIO, one to GND and the other to DIGITAL IN [See diagram in EZIO Setup]. Unlike the analogue sensors, you cannot connect digital sensors to the A/D inputs and so are limited to 10 connections.

Sensor Care

Mercury switches

- be extremely careful with these as the mercury inside is highly toxic. It is suggested that you create a housing for the switch to protect it from accidental breakage.

Touch/Slide/Bend

- be careful not to crease these as this causes permanent contact and they will no longer work. This also applies to the pressure mats.

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