Hi, I'm Daniel Holmlund.
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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