Scratch(mBlock) Programming Design - Use the mBot Robot_Tiked

Implementation 2

Please design an mBot whose “line-follower sensor” can handle four different scenarios with a
return value (0 ~ 3) and adjust mBot so that it travels along the black line.

Draw a flow chart

Starts the robot

Detected return value

Return value=0? Return value=1? Return value=2? Return value=3?

True True True Status=1? Status=2?
Detects repeatedly Status=1 Status=2

Runs forward Turns left slightly Turns right slightly Turns right broadly Turns left broadly

mBlock program

Chapter 7 Robotic Tracking Vehicle (Line-Follower Sensor) 151

Implementation 3

Pertaining to the previous question, and add the following two functions:
1. It will only start when the user presses the “button”.
2. It will only stop when the light sensor detects “dark light”.

mBlock program

152 Scratch (mBlock) Program Design — Using mBot Robot

7-7

Robot Stops when Detecting Third Black Line

As described earlier, although the robot's tracking car is able to use the "line-follower sensor" to run
forward along the black line, it is unable to record the journey during the process of walking. Therefore,
this unit will describe that how the mBot uses the "line-follower sensor" to stop when it detects the
third black line. Shown in the below schematic diagram:

mBot stops

Flow chart mBlock program

When double-clicking the
“mBot program”

The judgment button
is pressed
Count=0

Return Value=Line-follower
sensor Return Value

Count<3

False True
mBot stops Runs forward

Return Value=0
True

Count=count+1

Chapter 7 Robotic Tracking Vehicle (Line-Follower Sensor) 153

7-8
Tracking Robot That Plans to Automatically Park

Rule of the black line on-site

As the two “IR sensors” within the line-follower sensor are 1.2 cm apart, therefore the black line in
this topic has a limit of 1cm.

Implementation

The robot is parked in a designated “parking grid”. Assuming the robot wants to stop at the first
“parking grid”. The program then also has to judge if the variable is 6 while tracking and if so, the robot
will have its body “turn right 90 degrees” to enter the lot.

parking grid 1 parking grid 2 parking grid 3 Starting point

parking grid 4 parking grid 5 parking grid 6

Method — Using “four branches” to determine each scenario

1. When the robot's “left and right are both white”. That is, sense of light from both left and right does
not detect any black line, thus “go straight”.

2. When the robot's “left is white, and right is black”. That is, the sense of light on the right detects a
black line (robot leans to the left), thus you must turn right (small adjustment).

3. When the robot's “left is black, and right is white”. That is, the sense of light on the left detects a
black line (robot leans to the right), thus you must turn left (small adjustment).

4. When the robot's “left and right are both black”. That is, sense of light from both left and right
detects a black line so it will only turn black at an intersection or at the destination. You can thus
change the action according to the purpose.

Branch 1 Branch 2 Branch 3 Branch 4
Go straight Assigned action
Turns right Turns left
(small adjustment) (small adjustment)

White White White Black Black White Black Black

Solution

To store together with “variables”, and when encountering an “intersection”, the variable is increased
by one.

154 Scratch (mBlock) Program Design — Using mBot Robot

Chapter

7 Review questions

Short Answer Questions

1. Please design an mBot that, while walking, if it leans to the right, it must turn left
and issue a “Do sound”. On the contrary, if it leans to the left, it must turn right and
issue a “Re sound”. That is, there will be warning sound when the robot’s tracking
car deviates.

2. Pertaining to the above question, please add a start function by adding a “button”.
That is, the tracking will only start when the user presses the “button” on the
“mCore controller”.

3. Pertaining to the above question, please add a “dark light” switch to control mBot
walking. That is, the tracking stops when the user's hand covers the “light sensor”
on the "mCore controller”.

4. This chapter introduces the robot’s tracking car, and at the same time, will go

straight when a “black line” is detected. However, this method may not work well

in a more complicated route map. Therefore, please modify such that it will only go

straight when the “left is black, and right is white” is detected.

Illustration

480cm

120cm End

Starts Scenario   

Scenario Sensor1 Sensor2 Return value Adjustment action
(left side) (right side) 0 Turns right(spins)
On the black line Detects Detects color 1 Runs forward
Leans 2 Turns left(spins)
Black Black 3 Turns right
to the right side
Leans Black White

to the left side White Black
Deviates from the
White White
black line

Chapter 7 Robotic Tracking Vehicle (Line-Follower Sensor) 155

156 Scratch (mBlock) Program Design — Using mBot Robot

Chapter 8 CHAPTER OBJECTIVES

Remote-Controlled • To let the reader understand the
Robot principle of the transmitter and
receiver ends of the mBot “IR
(Infrared Sensor) sensor.

• To let the reader understand the
related applications of the mBot “IR
sensor”.

CHAPTER OUTLINE

8-1 Understanding Infrared Sensor
8-2
Determining Value of Infrared
8-3 Sensor
8-4
Infrared Sensor of Wait Module
8-5
8-6 Infrared Sensor of Switch
Module
8-7
Infrared Sensor of Loop Module

Remote-Controlling mBot
Movement

Sending Messages Between 2
mBots

8-1
Understanding Infrared Sensor

Definition
Used to transmit and receive messages to other robots or devices.

Classification

1. IR Transmitting: is used to send an mBot message to another mBot receiver.

2. IR Receiver: is used to receive another mBot’s transmitted message or an “IR remote control”
signal.

Exterior diagram mBot controller (Actual photo)

mBote controller (Flat diagram)

AA Battery 3.7V Lithium RGB LED RJ 25 port
holder interface battery interface
AA Battery 3.7V Lithium
Rehsoeldter interface battery interface
USB coRnenseect tor
USB connector Power switch RGB LED BuRzJz2e5r port

RJ 25 port Power swMitcohtor interface Buzzer
RJ 25 port
RGRBGLBEDLED Motor interface IR Receiver
IR ReLceigivhetrsensor
BuBzzuezrzer RJ 25 port Light sensor
IRIReRceicveriver RJ 25 port
IRIRTrTanrasnmsitmteirtter RGB LEDRGB LED IR TransmitteIrR Transmitter
Button Button
Light senLsiogrht sensor Button Button Motor interface
Motor interface

Purpose Controlling the robot
(Use the IR receiver to receive messages)
mBot remote control
(The front has a transparent small bulb (IR

transmitter))

158 Scratch (mBlock) Program Design — Using mBot Robot

mBot controller - Illustration

The second mode:

Avoid self-propelled car

The rst mode: The third mode:

Remote control car Tracking self-propelled car

Go forward Go right
Go left Go backward

Adjust speed of
self-propelled car

Description

1. The first mode: Use the “arrow keys” on the remote control to control the mBot’s walking
direction, and with the “number keys” to adjust the walking speed.

2. The second mode: The mBot when walking forward uses the “ultrasonic sensor” to detect if
there is an obstacle. If there is, it will automatically avoid the obstacle, if there isn’t, it will run
forward.

3. The third mode: mBot walks along the pre-set “black line or white line” using the "line-follower
sensor".

First mode Second mode Third mode

Application

1. Control an mBot’s action remotely.

2. Two mBot sending messages to each other.

3. Controlling the robots to march as a brigade remotely.

Chapter 8 Remote-Controlled Robot (Infrared Sensor) 159

8-2
Determining Value of Infrared Sensor

Detects messages sent by the “remote control” in the mBlock program development
environment.

mBlock program The type of messages sent by the IR remote control

Test the message sent by the “remote control” Press “B” on the remote control

Press “A” on the remote control

Test Results The message “B” is displayed

The message “A” is displayed

回傳值= A 回傳值= B

The range of messages sent

Basically, the English words “A ~ F” on the “remote control”, the four direction keys and the
numbers 0 ~ 9 are the messages sent.

160 Scratch (mBlock) Program Design — Using mBot Robot

8-2.1　Messages sent by remote control (control 2 LEDs)

In the previous unit, we have learned how to detect the value of the IR sensor. Next, we will learn
how to use the “remote control” to send messages (control 2 LEDs).

Implementation

Please write an mBlock program to control the “traffic lights” remotely. That is, Led1 will light up in
red when the “A” key is pressed, while Led2 will light up in green when the “B” key is pressed.

Flow chart

When double-clicking the
“mBot program”

Press “A” on True “Red” light in
IR remote control True LED1 lights up
False “Green” light in
LED2 lights up
Press “B” on
IR remote control

mBlock program

Chapter 8 Remote-Controlled Robot (Infrared Sensor) 161

8-2.2　Remote control to send messages (control 2 LEDs flashing)

In this unit, we will learn how to use the “remote control” to send messages (control 2 LEDs
flashing).

Implementation

Bearing to the previous unit, please add another function, which is, by pressing the “C” key, Led1
and Led2 will flash 3 times.

Flow chart

When double-clicking the
“mBot program”

Press “A” on True “Red” light in
IR remote control LED1 lights up

False True “Green” light in
Press “B” on LED2 lights up
IR remote control
False
Press “C” on
IR remote control

Repeats 3 times “Red” light in LED1 lights up
“Green” light in LED2 lights up

Wait for 0.5 seconds

LED1 does not light up
LED2 does not light up

Wait for 0.5 seconds

162 Scratch (mBlock) Program Design — Using mBot Robot

mBlock program

Three common methods of using the IR sensor

The IR sensor in mBlock is often used by the following three functional Blocks.
Wait

Loop

Switch

Chapter 8 Remote-Controlled Robot (Infrared Sensor) 163

8-3
Infrared Sensor of Wait Module

Function
It is set to implement the next action only when the “IR sensor” detected value is equivalent to a
certain” message”.

Wait

Detected value Returned message

Example

The robot runs forward and only stops when the “IR sensor” detects a message that is equal to “A”.
Please use Wait. [Please use Wait]

Answer

Flow chart mBlock program

When double-clicking the
“mBot program”

The robot runs forward

False Detects “A”
being pressed?
True

mBot stops

164 Scratch (mBlock) Program Design — Using mBot Robot

8-4
Infrared Sensor of Switch Module

Definition
It is used to determine if the “IR sensor” detected value is equal to a “message”. If “yes”, it implements
the branch “above”, otherwise the branch “below” is implemented.

Switch Detected value Message

１
2

Description
1. When the conditional is “true”, the branch “above” is implemented.
2. When the conditional is “false”, the branch “below” is implemented.

Example

The robot runs forward and only stops when the “IR sensor” detects a message that is equal to “A”.
[Please use Switch].

Answer

Flow chart mBlock program

When double-clicking the
“mBot program”

Message = 0

Detects “A” being pressed?
True
Message = A

Message = A

True False
mBot stops runs forward

Chapter 8 Remote-Controlled Robot (Infrared Sensor) 165

8-5
Infrared Sensor of Loop Module

Definition
It ends Loop when the “IR sensor” detected value is equivalent to a certain “message”.

Loop

Detected value Threshold value

Example

The robot runs forward and only stops when the “IR sensor” detects a message that is equal to “A”.
[Please use Loop].

Answer

Flow chart mBlock program

When double-clicking the
“mBot program”

The robot runs forward

False

Detects “A” being pressed?

True
mBot stops

166 Scratch (mBlock) Program Design — Using mBot Robot

8-6

Remote-Controlling mBot Movement

In fact mBot, in the original publication, and then through the “connection / Reset Default
Program” in the mBlock language, allows children or their parents to operate the robot through the “IR
remote control”, and also to switch to self-propelled vehicles. For example: remote control cars,
obstacles-avoiding cars and tracking cars.

In this unit, I will introduce, amongst them, on how to write an mBlock program to “control mBot
remotely”.

mBot remote control – Illustration

Second mode:
Obstacles-avoiding self-propelled cars

First mode: Third mode:
Remote control cars Self-propelled tracking cars

Faces forward Faces right
Faces left Faces backward

Adjust speed of
self-propelled car

Pertaining to the first mode in the diagram above, the “arrow keys” on the remote control are used
to control the direction of the mBot walking. The “number keys” are used together to adjust its walking
speed.

Chapter 8 Remote-Controlled Robot (Infrared Sensor) 167

Answer Flow chart

When double-clicking the De nition Change
“mBot program” power subroutine
Power = 160
“1” is pressed True Power = 100
on the remote control

“↑” is pressed on True Forward “2” is pressed True Power = 150
the remote control speed Power on the remote control

False True Backward False True Power = 200
“↓” is pressed on speed Power “3” is pressed
the remote control on the remote control
True Left turn
False speed Power False True Power = 255
“←” is pressed on “4” is pressed
the remote control True Right turn on the remote control
speed Power
False mBot stops
“→” is pressed on
the remote control

False
Change power

mBlock program

168 Scratch (mBlock) Program Design — Using mBot Robot

Results of implementation Controlled robot
(Using IR Receiver to receive messages)
mBot remote control
(There’s a transparent bulb at the front (IR

Transmitter))

Chapter 8 Remote-Controlled Robot (Infrared Sensor) 169

8-7
Sending Messages Between 2 mBots

An mBot or the addition of an IR remote control is constantly used in the previous unit.

In this unit, we will use the (IR Transmitter and Receiver) in the mainboard of every mBot for the
transmission of messages.

IR remote control Receives “remote control” and “Receives” messages from
“transmit” messages another mBot

Implementation)

Assume there are two mBots and an IR remote control.

Now you want to use the “IR remote control” to first send a signal to robot A, and after robot A’s
(transmitter) receives the signal from the remote control, will then send to robot B’s (receiver) to
control its actions.

Answer

Flow chart of the “Transmitter”

When double-clicking the
“mBot program”

“↑” is pressed True Send mBot message 1
on the remote control True

False Send mBot message 2
“↓” is pressed True Send mBot message 3
on the remote control True Send mBot message 4

False
“←” is pressed
on the remote control

False
“→” is pressed
on the remote control

170 Scratch (mBlock) Program Design — Using mBot Robot

Flow chart of the “Transmitter”

When double-clicking the
“mBot program”

Send mBot message 1 True Runs forward 2 seconds
True Runs backward 2 seconds
False True Turns left 2 seconds
Send mBot message 2 True

False Turns right 2 seconds
Send mBot message 3

False
Send mBot message 4

Transmitter Receiver
(To upload the program to mBot’s (To upload the program to mBot’s “Receiver”)

“Transmitter”)

Chapter 8 Remote-Controlled Robot (Infrared Sensor) 171

Chapter

8 Review questions

Short Answer Questions

1. Infrared light relay race _ straight line
Please prepare two mBots; one as the “transmitter”, and the other as the
“receiver”. When the robot, who is the “transmitter” gets to about 10cm
close to a robot, who is the “receiver”, whilst walking in a “straight line”, it
will send a signal to the “receiver” through infrared light. When the “receiver”
receives the signal, it will then run forward in a “straight line” so as to achieve
the purpose of the robot relay race.

2. Infrared light relay race_ follows track
Please prepare two mBots; one as the “transmitter”, and the other as the “receiver”.
When the robot, who is the “transmitter” gets to about 10cm close to a robot, who
is the “receiver”, whilst walking in a “circle”, it will send a signal to the “receiver”
through infrared light. When the “receiver” receives the signal, it will then run
forward in a “circle” so as to achieve the purpose of the robot relay race.

172 Scratch (mBlock) Program Design — Using mBot Robot

Chapter 9 CHAPTER OBJECTIVES

Robotic Solar • To let the reader understand the
Powered Vehicle principle of the transmitter and
(Light Sensor) receiver of the mBot’s “light sensor”

• To let the reader understand related
applications of the mBot’s “light
sensor”.

CHAPTER OUTLINE

9-1 Understanding Light Sensor
9-2
Determining Value of Light
9-3 Sensor
9-4
9-5 Light Sensor of Wait Module
9-6
Light Sensor of Switch Module
9-7
Light Sensor of Loop Module
9-8
Light Sensor Controlling Other
9-9 Block Modules

Making a Robotic Solar Powered
Vehicle

Making a Robotic Cockroach
Vehicle

Making a Smart Streetlamp

9-1
Sending Messages Between 2 mBots

Definition
It is used to detect the intensity of light in the environment.

Purpose

You can use the different light values in the surroundings to make the robot perform different
actions.

Exterior diagram

mBote controller (Flat diagram) mBot controller (Actual photo)

AA Battery 3.7V Lithium RGB LED RJ 25 port
holder interface battery interface
RGB LED RJ 25 port
AA Battery 3.7V Lithium Buzzer
holder interface battery interface Buzzer
Reset
Power switch
Reset MotPoor winetresrwfaictceh
USB connector
Motor interface
USB connector

RJ 25 poRrtJ 25 port RJ 2R5J p2o5rptort IR Receiver
RGB LEDRGB LED LLigighhttsseeInnRssRoorreceiver
RGBRGLBEDLED
Buzzer Buzzer IRIRTTrraannssmmiitttteerr MoMtoor tinotreirnfatceerface
IR ReceivIRerReceiver ButtBountton BBuutttotonn
IR TransmIRitTterarnsmitter LighLtigshetnsseonrsor

Exterior

The light sensor is located in the second row of the front part of the mBot.

Application

1. Create a robotic solar car.
2. Create a robotic cockroach car.
3. Create an intelligent streetlight (day (bright) → LED off, night (dark) → LED on).

174 Scratch (mBlock) Program Design — Using mBot Robot

9-2
Determining Value of Light sensor

Detecting “Light Values” in the mBlock program development environment

Test the value of the light source The hand moves up slowly
Detected light value (higher)
Put your hands about 1 cm above the light sensor

Test Results

Detected light value (lower)

Return value= 82 Return value= 994

Range of sensing value

Basically, the light sensors sense value has a range of 0 to 1023.
1. “Indoor” natural light: between 0 and 1000 (the greater the value, the brighter it is).
2. "Outdoor" natural light: exceeds 1000 (also possible if using a flashlight to shine “indoor”)

Three common uses of light sensor

The light sensor in mBlock is often used by the following three functional Blocks.
Wait

Loop

Switch

Chapter 9 Robotic Solar Powered Vehicle (Light Sensor) 175

9-3
Light sensor of Wait Module

Function
It is set to implement the next action only when the “light sensor” detects that the value is less than the
“threshold value”.

Wait

Detected value Threshold value

Example

The robot runs forward and will only stop when the “light sensor” detects a light value less than “500”.
[Please use Wait].

Flow chart mBlock program

When double-clicking the
“mBot program”

The robot runs forward

False
Detected light value<500
True
mBot stops

176 Scratch (mBlock) Program Design — Using mBot Robot

9-4
Light sensor of Switch Module

Definition
It is used to determine whether the reflected light detected by the “light sensor” is less than the
“threshold value”. If “yes”, the branch “above” will be implemented. Otherwise the branch “below” will
be implemented.

Switch

Detected value Threshold value

１
2

Explanation

1. When the conditional is “true”, the branch “above” is implemented.
2. When the conditional expression is “false”, the branch “below” is implemented.

Example

The robot runs forward and will only stop when the “light sensor” detects a light value less than “500”.
[Please use Switch].

Answer

Flow chart mBlock program

When double-clicking the
“mBot program”

Light Value = 0

Light Value = Detected light value

True Detected light value<500 False

mBot stops mBot runs forward

Chapter 9 Robotic Solar Powered Vehicle (Light Sensor) 177

9-5
Light sensor of Loop Module

Definition
Used to end Loop when the “light sensor” detects a light value that is less than the “threshold value”.

Loop

Detected value Threshold value

Example

The robot runs forward and stops when the “light sensor” detects a light value less than “500”. [Please
use Loop].

Flow chart mBlock program

When double-clicking the
“mBot program”

The robot runs forward

False
Detected light value<500
True
mBot stops

178 Scratch (mBlock) Program Design — Using mBot Robot

9-6
Light sensor Controlling Other Puzzle Modules

Assuming we have assembled a robot and want the speed of its movement to go according to the
different light value. At this point, we must use the “light sensor” to detect the “light value” of the
different light sources, and then have the “numerical data of the light value” send to the other rotational
speed of the “motor”.

Example

The light source controls the speed of the motor. After the “light sensor” detects and sends out the
reflected light intensity, it is, through the “division” operator of the “Operators Block” box, divided by
(3.92). The output is then sent to the motor as its “rotational speed” input.

mBlock program

Explanation

1. “Motor rotational speed” ranges from absolute values 0 ~ 255.
2. “Light sensor” ranges from 0 ~ 1023.
3. Therefore, 1023/255 ≒ 4 must be divided when changing the value of the light sensor into the

motor rotational speed.

Chapter 9 Robotic Solar Powered Vehicle (Light Sensor) 179

9-7
Making a Robotic Solar Powered Vehicle

Rules for a solar car

1. The robot begins to run forward in a straight line when light shines at the robot.
2. The robot stops when the light source is removed.

Site Requirements

Use your mobile phone’s “flashlight” or a traditional flashlight.

Flow chart

When double-clicking the
“mBot program”

Light Value = 0

Light Value = Detected light value

True Light Value> 1000 False

mBot stops mBot runs forward

Implementation

Please write an mBlock program to simulate a “solar car”. That is, when there is light shining on it, it
will automatically run forward, otherwise it stops.

mBlock program

180 Scratch (mBlock) Program Design — Using mBot Robot

9-8
Making a Robotic Cockroach Vehicle

Rules for a cockroach car

1. The robot does not move when light shines on the robot.
2. The robot runs forward in a straight line when the light source is removed.

Site requirements

Use your mobile phone's “flashlight” or a traditional flashlight.

Flow chart

When double-clicking the
“mBot program”

Light Value = 0

Light Value = Detected light value

True Light Value> 1000 False

mBot stops mBot runs forward

Implementation

Please write an mBlock program to simulate a “solar car”. That is, when there is light shining on it, it
will automatically run forward, otherwise it stops.

mBlock program

Chapter 9 Robotic Solar Powered Vehicle (Light Sensor) 181

9-9
Making a Smart Streetlamp

Thinking of the theme

Daytime (bright) → LED off, Night time (dark) → LED on

Method

Use two LED lights to simulate the intelligent streetlight.

Flow chart

When double-clicking the
“mBot program”

Light Value = 0

Light Value = Detected light value

True Light Value> 500 False

LED light off LED light on

Implementation

Please write an mBlock program to simulate the “intelligent street light”. That is, when there is light
shining on it, it will automatically turn the street light off. Otherwise it will turn the street light on.

mBlock program

182 Scratch (mBlock) Program Design — Using mBot Robot

Chapter

9 Review questions

Short Answer Questions

1. Please use the intensity of the light source to determine the tone of the buzzer.

Tone of mBlock

Scale C4 D4 E4 F4 G4 A4 B4

Mid tone 262 294 330 349 392 440 494
frequency

Scale C5 D5 E5 F5 G5 A5 B5

High tone 523 587 659 698 784 880 988
frequency

Piano notes Do Re Mi Fa So Ra Si

2. Please use the intensity of the light source to sound the piano notes, Do, Re, ...,
Si.(Seven notes to match the table)

Scale C4 Tone of mBlock
D4 E4 F4 G4 A4 B4
Piano notes Do Re Mi Fa So Ra Si
151~300 301~450 451~600 601~750 751~900 901~1050
Light values 0~150

Chapter 9 Robotic Solar Powered Vehicle (Light Sensor) 183

184 Scratch (mBlock) Program Design — Using mBot Robot

Chapter 10

CHAPTER OBJECTIVES

• To let the reader understand the
functions and principles of the
mBot’s button, buzzer, LED lights
and reset button.

• To let the reader understand the
various applications of the mBot’s
button, buzzer, LED lights and reset
button.

CHAPTER OUTLINE

10-1 Button
10-2 Detecting Incidents with [Button]
10-3 General Usage of Button
10-4 Buzzer
10-5 LED Light
10-6 Reset Button

Robotic Police Car
(Button_ Buzzer _

LED Light)

10-1
Button

Definition
Pressing the button in the mBot will command it to start implementing instructions.

Features
It is generally used to start the mBot program.

Example

When the user presses the “button”, it starts to execute the line-follower.

Exterior diagram

Application

1. Starts the mBot program.
2. Counter.

186 Scratch (mBlock) Program Design — Using mBot Robot

10-2
Detecting Incidents with [Button]

The event of detecting the “button” in the mBlock programming language

Testing the distance Hand “releases” button
Hand “releases” button
“Press” the button with your hand

Testing the distance

“Press” the button with your hand

Return Value Return Value

Testing the distance

The button in mBlock is often used in the following three functional Blocks.
Wait

Loop

Switch

Chapter 10 Robotic Police Car (Button_ Buzzer _LED Light) 187

10-3
General Usage of Button

In this unit, we will introduce using the “button” to design the various uses in your daily life.
Commonly seen as follows:

1. Hand presses the alarm. (Use Wait).
2. Hand presses the counter. (Use Switch).
3. Hand presses the alarm and warning light. (Use Loop).

10-3.1　Hand Presses the Alarm

When the user presses the “button”, then a “beep” sounds. (Use Wait).

Flow chart mBlock program

When double-clicking the
“mBot program”

If the button is pressed

True
“Beep” sounds

When the user presses the “button”, the counter is automatically increased by 1 in the Stage area.
(Use Switch).

10-3.2　Hand Presses the Counter

Flow chart mBlock program

When double-clicking the
“mBot program”

Counter = 0

If the button is pressed

True
Counter = Counter +1

188 Scratch (mBlock) Program Design — Using mBot Robot

10-3.3　Hand Presses the Alarm

When the user presses the “button”, an “alarm” will sound and a “warning light” is lit. (Use Loop).
Flow chart

When double-clicking the
“mBot program”

False If the button is pressed True

“Alarm” is sounded “Warning light”
“Warning light” lights up doesn’t light up

mBlock program

Chapter 10 Robotic Police Car (Button_ Buzzer _LED Light) 189

10-4
Buzzer

Definition
In an mBot, the buzzer can be said to be its “mouth”.

Features
Different frequency sounds are emitted according to the situations.

Example

When we “boot” or “reset”, “three beeps” will sound so that users understand the current situation.

Exterior diagram

Seven notes to match the table

Tone of mBlock

Scale C4 D4 E4 F4 G4 A4 B4

Mid range tone 262 294 330 349 392 440 494

Piano notes Do Re Mi Fa So Ra Si

190 Scratch (mBlock) Program Design — Using mBot Robot

10-4.1　The buzzer sounds the “Little star” music

Once you understand how the seven notes match the table, we can now use it to design a variety of
music.

Implementation

Little star 1155665 4433221 5544332 5544332 1155665 4433221

Explanation

Notation 1 represents Do on the mobile phone screen, 2 represents Re ~ 6 represents Ra, 7
represents Si, space represents stop.

Answer

The first two paragraphs of the code.

Chapter 10 Robotic Police Car (Button_ Buzzer _LED Light) 191

10-4.2　watchdog that barks

Using the “ultrasonic sensor” to simulate “a barking watchdog”.
Assuming “equation of speed of running forward and distance”: speed = (distance (cm) -30) * 10.

Answer

Flow chart

When double-clicking the
“mBot program”

If the button is pressed
True

Distance = Distance detected by ultrasonic

Distance = 30
True
Barking sound

Rotational speed of the motor running forward =
(Distance detected by ultrasonic – 30)* 10

mBlock program

192 Note The barking is represented by a “beep sound”.
Scratch (mBlock) Program Design — Using mBot Robot

10-5
LED Light

Definition
The LED lights in the mBot will show the different colors of the RGB.

Features
As a “Warning” purpose.

Example

When the “button” is pressed, the alarm will begin to sound and the LED will flash.

Exterior diagram

Explanation

There are two RGB LED lights (LED1 and LED2) on the controller.

Chapter 10 Robotic Police Car (Button_ Buzzer _LED Light) 193

10-5.1 Button to Switch the Two LEDs to Exchange the
Displays

In the previous unit, we have learnt the basic concept of the two RGB LED lights. Next, we will use
the button to show how the LED displays are switched.

Implementation

Please use the “button” to switch between the two LED displays.

Answer

Flow chart mBlock program

When double-clicking the
“mBot program”

Counter = 0

If the button is pressed

Count = Count + 1
Status = odd or even value

LED does not light

True Status = 1 False

LED1 lights up LED2 lights up

194 Scratch (mBlock) Program Design — Using mBot Robot

10-5.2　Button to Switch the LED to Sound DoReMi

In the previous unit, we have learnt the basic concept of the two RGB LED lights.
Next, we will use the button again to switch the LED to play DoReMi.

Implementation

Use the “button” to switch between two LED displays and to play DoReMi.

Answer

Chapter 10 Robotic Police Car (Button_ Buzzer _LED Light) 195

10-5.3 Button to Activate the LED to Play the Sound of an
Ambulance

In the previous unit, we have learnt the basic concept of the two RGB LED lights.
Next, we will use the button to activate the LED to start playing the sound of an ambulance siren.

Implementation

Please use the “button” to switch between the two LED displays, and play the sound of an
ambulance siren.

Answer

196 Scratch (mBlock) Program Design — Using mBot Robot

10-6
Reset Button

Features
Used to close the program that is being implemented.

Example

While you use the “button” start a program, you can close it using the “reset button”.

Exterior diagram

Chapter 10 Robotic Police Car (Button_ Buzzer _LED Light) 197

Chapter

10 Review questions

Short Answer Questions
1. 1. Please design the sound of a “fire engine” siren.
2. 2. Please design the sound of a “police car” siren.

198 Scratch (mBlock) Program Design — Using mBot Robot

Chapter 11 CHAPTER OBJECTIVES

Bluetooth • To let the reader understand the
Communications basic concept and application of the
mBot Bluetooth communications
Application module.

• To let the reader understand how
send characters, light up the
mBot LED lights and receive mBot
ultrasonic distance through the
pairing of a mobile phone and mBot
Bluetooth.

CHAPTER OUTLINE

11-1 mBot Bluetooth Communications

11-2 m B l o c k C o m m u n i c a t i o n s
Component

11-3 Pairing mBot Bluetooth and
Phone

11-4 Mutual Transmission between
mBot and Phone

11-5 Lighting mBot LED Light With
Phone

11-6 R e c e i v i n g m B o t U l t r a s o n i c
Distance with Phone

11-1

mBot Bluetooth Communications

As the robot can be fitted with a wide range of sensors, using it can facilitate us in the collection of
information. It therefore allows us to enter the domain of IoT, the current mainstream internetworking
area, easily. Of which Bluetooth communication being the key technology.

Coupled with the fact that mobile phones are now like a part of our arm, resulting in IoT being
realized in our lives in general. Whether it is for schoolwork, work or entertainment purposes, the
mobile phone’s Bluetooth device is an important part in the realization of IoT.

In this chapter, I will introduce the use of the “Bluetooth communications module” on the mBot’s
mainboard. Its purpose is to allow your Android mobile phone to communicate with the mBot
Bluetooth.

Flow chart on the uses of the Bluetooth module

Install the Bluetooth module Compose the program for
the communication
component Write App

Connects PC USB cable Turn the power back
to mBot on for the mBot

Turn on mBot power Mobile phone is connected
to the mBot

Open mBlock software Mobile phone starts
communications with mBot

Select the serial port

200 Scratch (mBlock) Program Design — Using mBot Robot