Ultrasonic Sensor

LEARNING TARGETS:

1. I can define the term sensor.

2. I can identify the different parts of ultrasonic sensor.

3. I can install ultrasonic sensorwith ease and accuracy

3. I can write a code involving sensors

ESSENTIAL QUESTION:

How can the mastery of the common competencies in
Robotics help us be better citizens of our community?

WHAT DOES ELECTRONIC SENSOR MEAN?

❑ A

sensor

is

a

device

that

measures physical input from its
environment and converts it into
data that can be interpreted by
either a human or a machine. Most
sensors are electronic (the data is
converted into electronic data), but
some are more simple, such as a
glass thermometer, which presents
visual data.

HOW THE HC-SR04 ULTRASONIC DISTANCE SENSOR

WORKS?

❑It emits an ultrasound at 40
000 Hz which travels through
the air and if there is an object
or obstacle on its path It will
bounce back to the module.
Considering the travel time and
the speed of the sound you can
calculate the distance.

HOW THE HC-SR04 ULTRASONIC DISTANCE SENSOR

WORKS?

❑In

order

to

generate

the

ultrasound we need to set the Trig
pin on a High State for 10 µs. That
will send out an 8 cycle ultrasonic
burst which will travel at the speed
of sound. The Echo pins goes high
right away after that 8 cycle
ultrasonic burst is sent, and it starts
listening or waiting for that wave
to be reflected from an object.

HOW THE HC-SR04 ULTRASONIC DISTANCE SENSOR

WORKS?

❑If

there

is

no

object

or

reflected pulse, the Echo pin will
time-out after 38ms and get
back to low state.

HOW THE HC-SR04 ULTRASONIC DISTANCE SENSOR

WORKS?

❑If we receive a reflected pulse,
the Echo pin will go down sooner
than those 38ms. According to the
amount of time the Echo pin was
HIGH,

we

can

determine

the

distance the sound wave traveled,
thus the distance from the sensor to
the object.

HOW THE HC-SR04 ULTRASONIC DISTANCE SENSOR

WORKS?

❑If

there

is

no

object

or

reflected pulse, the Echo pin will
time-out after 38ms and get
back to low state.

HOW THE HC-SR04 ULTRASONIC DISTANCE SENSOR

WORKS?

❑For that purpose we are using
the following basic formula for
calculating distance:
❑Distance = Speed x Time

HOW THE HC-SR04 ULTRASONIC DISTANCE SENSOR

WORKS?

❑We actually know both the speed and the
time values. The time is the amount of time
the Echo pin was HIGH, and the speed is the
speed of sound which is 340m/s. There’s
one additional step we need to do, and
that’s divide the end result by 2. and that’s
because we are measuring the duration the
sound wave needs to travel to the object
and bounce back.

❑Distance = Speed x Time

Let’s say the Echo pin was HIGH for 2ms. If we want
the get the distance result in cm, we can convert the
speed of sound value from 340m/s to 34cm/ms.

Distance = (Speed x Time) / 2 = (34cm/ms x 1.5ms)
/ 2 = 25.5cm.

So, if the Echo pin was HIGH for 2ms (which we
measure using the pulseIn() function), the distance
from the sensor to the object is 34cm.

https://www.youtube.c
om/watch?v=HynLoCtU
VtU

https://create.arduino.cc/e
ditor/mertarduinotech/b70
22e05-f709-4003-b2a7-
5c487ee25007/preview

​https://www.tinkercad.com/things/2xUVczrN6D2-ultrasonic-sensor/editel?sharecode=fzVWSvssO5XDftXP-2-3EfsICIq_4yappUhOcAtEzhc