Editing Sensors

== What are sensors? ==

Sensors are devices which measure some physical quantity or movement and send an electrical signal back to Smart Box.
This in turn converts the signal into a form that the software can understand.
The sensors provide ''feedback''.
An example of a system involving feedback might be a plant heating system.
The computer can switch on and off a heater, but it needs to be able to measure the temperature of the environment being controlled in order to determine when to switch the heater on and off.
Sensors can either be Digital or Analogue.
Analogue sensors produce a voltage which can vary continuously, but like most computers, Smart Box can only handle digital signals internally.
An analogue to digital convertor converts the analogue signals into a form that Smart Box can understand.

=== Analogue sensors ===

[[File:Sensor-Light-Small.svg|frame|left|Light sensor]]

Smart Box has a number of sockets which enable you to connect sensors that can be used to monitor and measure the environment.
These sensors plug into any one of the four analogue sensor sockets on the side of the case.
The Smart Move software can identify which analogue sensors are connected and calibrate the software accordingly.
A range of sensors can be connected to the analogue sockets including light, sound, position and humidity.

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=== Digital sensors ===

[[File:Sensor-Microswitch.svg|frame|left|Microswitch]]

Digital sensors are connected to the red and yellow sockets on the top of the case.
The software can detect if the switch connected between the sockets is open or closed.
Digital sensors are useful for detecting a ‘condition’ such as when a door is open or when a buggy has hit a wall.
The digital sensor inputs can also be used for counting.
For example the rotation of a wheel can be accurately controlled if a microswitch is positioned so that it is closed as the wheel rotates.

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== Making your own sensors ==

You can make your own analogue and digital sensors for use with Smart Box.
Analogue sensors tend to be slightly more complex as they produce a voltage which varies depending on the condition of the sensor.
Digital sensors on the other hand simply complete the circuit between the red and yellow sockets.

=== Analogue sensors ===

You can connect your own analogue sensors to Smart Box via the sensor adaptor.
This brings the connections from the analogue sensor sockets to 4mm connectors on the lid of the adaptor.
The sockets are marked Input, Ground and Vref.

The Smart Sense range of analogue sensors are identified by Smart Box when they are plugged in.
The sensor adaptor allows other sensors to be recognised.

The voltage between the input and ground sockets should vary between 0 volts and a maximum of 2.55 volts.
The Vref socket provides a 2.55 voltage source.
The inputs to Smart Box are protected against over voltage.

=== Digital sensors ===

[[File:Sensor-Switch.svg|left]]

The eight input sockets on the top of the box simply require a connection to be made between them.
This can be a switch such as a push switch or microswitch, or any device which will complete the circuit.
Connect your ‘switch’ to Smart Box using a length of 2 core cable terminated with 4 mm plugs.

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[[Category:Smart Box]]