In this video we're going to do a quick overview of sensors

and actuators and take a closer look

at what's provided inside the Grove IoT Sensor Kit.

A sensor is defined as a device that

can record a measurement about its physical environment.

This measurement can then be converted

into an electrical signal that can be read by an Arduino 101

and is forwarded to a gateway or to the cloud

for additional processing.

The electrical signal connects to the Arduino

with a couple of different types of connectors.

Sensors encode their data in different ways

in order to best represent the data to the computer system

they talk to.

The first type is a digital sensor.

The Grove Button and the Switch are both examples that

send simple digital signals.

They're either on or they're off.

The second type is a digital actuator.

The Grove Buzzer and Grove LTD are both digital actuators.

That is they can change their state

and perform an action depending on whether on or off signal

is sent to them.

The Buzzer will make a noise and the LCD will light up

when a high signal was sent.

They both deactivate when the signal is low.

On the Arduino 101, a voltage of 3.3 volts

is considered on or high and a voltage of zero

is considered off or low.

The Grove Temperature Sensor, Rotary Angle Sensor,

and Light Sensor are examples of analog sensors.

This means that they receive a voltage somewhere between zero

and 3.3 volts.

The Arduino 101 has an analog to digital converter,

or ADC, which takes the signal and converts it

into a 10-bit number, which is a number between zero and 1023.

So, for example, if a sensor is sending a voltage of 1.65 volts

to the Arduino, the converter would read this

as approximately 512.

Lastly, the LCD screen is an actuator

that is capable of displaying a message

and illuminating its backlight to any eight-bit color.

It's not a simple digital or analog device.

It uses a serial communication protocol called I squared C.

The I squared C protocol allows devices

to communicate their internal timing clocks

and then communicate data using a serial protocol.

I squared C devices can be chained,

meaning that multiple devices can be attached.

And together, these devices are said

to be on an I squared C bus.

Each device is given an address that can

be communicated to on that bus.

In the video on MRAA and UPM, we'll

see how to use a higher level software

library to abstract away these details

and to give an easy-to-use interface to more

complicated devices.

Thank you very much for watching.

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