1. Product introduction

Solve teaching pain points and elaborate optimization design

In STEM large-class teaching, teachers often face many problems. For example, poor-quality and complex-to-use products can become obstacles to teaching. In a classroom of dozens of people, any small problem with a product may cause a chain reaction, resulting in the entire class being busy solving various strange problems of students. At the same time, how to quickly stimulate students' interest and create a good classroom atmosphere is also a key point of teaching. Maqueen V5 has been elaborately optimized and designed precisely to solve these problems.

Line-following in just one step

1. Optimized line-following probe and algorithm

Line-following driving is an extremely interesting and important project in STEM robot teaching, but problems often occur due to the poor line-following function of educational cars, such as line-following failure and poor effect, causing frequent situations in classroom teaching. Maqueen V5 has made significant improvements by increasing the number of line-following sensor probes from 2 to 3 and innovatively embedding the line-following algorithm in the underlying chip.

Smooth line-following can be achieved with just one program module, making the line-following function extremely simple. Teachers no longer need to worry about classroom "upsets" caused by line-following problems, and students can quickly experience the interesting line-following function, thereby quickly mobilizing their learning interest and classroom atmosphere.

2. Multifunctional parallel advantage

Since the line-following algorithm is built into the underlying chip, it is equivalent to adding an operational core to the robot. This enables micro:bit to apply more functions simultaneously during line-following without interference, such as obstacle avoidance, flashing lights, reading sensors, displaying and switching images while line-following, greatly enriching the teaching content and students' practical experience.

Reliable motor components

1. Fine parameter matching and protection design

Maqueen V5 adopts finely parameter-matched metal motors. Through repeated tests and verifications of more than 30 motor samples, careful adaptations have been made in performance, reliability, and speed to ensure smooth and non-jamming motor rotation. At the same time, overall protection has been provided for the motors, and the gearbox is no longer exposed, significantly reducing the risk of hair and other debris entering the gearbox and damaging the motors.

2. Detachable design guarantees teaching

In the classroom, students are full of curiosity about the robot and may accidentally crush or break the precise motor components. Considering this, Maqueen V5 adopts a detachable motor design. Once the motor is damaged, it can be replaced quickly to ensure the smooth progress of teaching.

Convenient out-of-the-box experience

In classroom teaching, the complex installation process is often a headache. Especially when there are a large number of students, installation errors can cause various problems, resulting in the inability of the car to function properly. Maqueen V5 is fully installed with motors, battery boxes, wheels, etc. at the factory. The battery box is firmly fixed on the base plate with copper columns. Teachers and students do not need to install it and can use it directly out of the box, saving valuable time and energy for teaching.

Interesting light perception and lighting design

1. Interesting light perception ability

Light perception is as important for robots as eyes are for humans and is one of its essential sensing devices. The ability to distinguish the position of light perception can bring interesting gameplay and quickly stimulate students' interest in robots. Maqueen V5 has on-board 2 channels of light intensity sensors, located on the left and right sides in front of the car, with the ability to locate the light source position and detect light intensity, enabling interesting applications such as light seeking, light chasing, light avoiding, and automatic car lights.

2. Attractive lighting effect

Colorful lights are very attractive to children. Maqueen V5 adopts 2 oversized color RGB front headlights and 4 color RGB ambient lights. The lights and sensors cooperate with each other to create a unique visual effect.

Other considerate functions

Maqueen V5 also has some user-friendly and considerate functions waiting for everyone to discover:

1. Battery power reading function, allowing you to obtain the remaining battery power at any time.
2. Firmware upgrade function.
   Etc.......

2. Maqueen Function Comparison

3. Product parameters

Power supply parameter

• 3.5V - 5V, 3 AA batteries, 1.5V alkaline batteries or 1.2V nickel-metal hydride batteries
• Battery reverse connection protection: Supported

Line-following sensor

• Number of line-following sensors: ×3
• Calibration button for line-following sensors: ×1
• Output value of line-following sensors: Switching quantity / Analog quantity
• Built-in line-following function on the chip: Supported
• Built-in line-following speed on the chip: 1 gear

RGB light

• Number of WS2812 RGB: ×4
• Number of display colors of WS2812 RGB lights: R255 × G255 × B255
• Number of RGB vehicle lights: ×2
• Display colors of RGB vehicle lights: Red, Green, Yellow, Blue, Purple, Cyan, White

Light sensor

• Number of light sensors: ×2
• Data range: 0 - 1023

Ultrasonic sensor

• Model of ultrasonic sensor: H-SR04
• Number of ultrasonic sensors: ×1
• Supply voltage: 5V
• Data interface: IO port
• Interface form: 2.54 female header
• Measuring range: 5cm - 50cm when installed on the car / 5cm - 300cm when not installed on the car
• Measuring accuracy: ±5cm

Motor

• Number of motors: ×2
• Model of motor: N20 metal motor
• Motor interface: 2.54 male and female headers
• Motor power supply: Direct power supply by battery
• Motor disassembly method: Fixed and disassembled by screws

Infrared and buzzer

• Number of infrared receiving sensors: ×1
• Number of buzzers and switches: ×1

Expansion interfaces and other configurations

• Number of PCB threaded interfaces: ×6
• Firmware upgrade interface and button: ×1 (Reused with the calibration button)
• Number of expansion GPIO: ×3
• Number of expansion I2C: ×2
• Servo motor interface: ×2
• Goldfinger interface: ×6

4. Safety Precautions

Since Maqueen is a STEM education product and is presented in a bare - board form, the following safety precautions should be noted during use:

1. The use of batteries must strictly comply with the battery usage methods and safety precautions. Otherwise, it may damage the product and cause risks such as overheating and combustion.
2. Do not touch the product, especially the circuit board part and the battery part, with sharp objects like screwdrivers. This is to avoid damaging components or causing danger.
3. Do not touch the product's circuit board with metal objects to prevent short - circuits, which can damage the product and lead to risks such as overheating and combustion.
4. The product is not waterproof and should not come into contact with liquid substances such as water and beverages. If liquid is accidentally spilled on the product, immediately turn off the power and remove the battery. Only attempt to power it on after the moisture has completely dried.
5. When storing the product, do not stack multiple products together to avoid component damage, and even the risk of power short - circuits, which may cause fires and personal injury.

5. Preparation Work

5.1 Plug in the micro:bit mainboard

Be careful not to insert it in the wrong direction, as shown in the figure.

5.2 Install the battery

Pay attention to the installation direction of the positive and negative electrodes of the battery.

Incorrect installation will prevent normal operation and even damage the device or cause danger.

5.3 Turn on the power switch

Move the power switch to the "ON" side to turn on the power switch. At this time, the power indicator light will light up.

6. MakeCode Sample Tutorial

6.1 Open the MakeCode platform and load the library

Click the link to enter the MakeCode graphical programming platform: https://makecode.microbit.org/

Click "New Project" to create a new project, as shown in the figure:

图片

In the pop-up dialog box, give a name to the project, and then click "Create" as shown in the figure:

Load the Maqueen library:

Click the "Settings icon" and then click "Extensions", as shown in the figure:

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In the search box, enter dfrobot, and then click the search button. Select "Maqueen", as shown in the following picture:

The library loading is completed. The loaded library is shown as follows:

6.2 RGB Car Light

Function Description

Maqueen V5 has two large-sized colorful front headlights. It can display 7 colors. And it also has the flashing function and the gradient function.

Example 1: Light up the car headlights

This example demonstrates that the two headlights are displayed in red for one second, then turned off for one second. This cycle repeats.

Example 2: Change the color of the car headlights

This example demonstrates that the colors of the two headlights are switched at intervals of one second.

Example 3: Background flashing of the car headlights

Maqueen V5 supports the background flashing of the headlights, which is a characteristic function of Maqueen. Just send one instruction, and it can flash cyclically. The number of flashes, the flashing frequency and the flashing color can be set. And it can be interrupted in real time to turn off the headlights.

This function enables the headlights to flash cyclically without affecting other program processes.

Note: This function is mainly used in "on start". When used in "forever", the effect may not be good due to timing reasons.

Example 4: Background Gradient of the Car Headlights

Maqueen V5 supports the gradual display of colorful lights for the headlights in the background. It is a characteristic function of Maqueen. Just send one instruction, and the headlights can gradually display different colors.

This function enables the headlights to change colors when lit without affecting other program processes.

Note: This function is mainly used in "on start". When used in "forever", the effect may not be good due to timing reasons.

6.3 WS2812 RGB Ambient Light

Function Description

Maqueen V5 has 4 WS2812 RGB ambient lights onboard at the bottom. They are connected to the P15 interface of micro:bit. These 4 ambient lights support full-color display.

To use the ambient lights, you first need to load the "neopixel" library in makecode. The method is shown as follows:

Click the Extensions button:

Search for "neopixel", and then select "neopixel", as shown in the figure:

Example 1: Light up the ambient lights

This example shows the switching display of nine colors for the ambient lights.

Example 2: Breathing Light Color Fusion

This example demonstrates the gradual fusion effect of the breathing state of the ambient lights by setting the RGB color values.

Example Link: https://makecode.microbit.org/_Ao1L5tUXaEkj

Example 3: Rotating Flowing Water Lights

This example demonstrates the effect that the ambient lights present the flowing water lights lighting up one by one.

Example 4: Rotating Rainbow Lights

This example demonstrates that the ambient lights display a gradual rainbow color and present a dynamic switching effect.

Among them, the hue of the rainbow color can be adjustable within the range from 1 to 360, and different color effects will be presented.

6.4 Buzzer

Function Description

Maqueen V5 integrates a buzzer and a switch, which are located at the bottom of the car. By driving the buzzer, the car can emit alarm sounds or various kinds of music.

The Microbit V2 mainboard integrates a buzzer, while the Microbit V1 mainboard does not integrate a buzzer. If you are using Microbit V1, then you can use the buzzer on the car's baseplate. If you are using V2, then you can freely choose whether to use the buzzer integrated in the Microbit or the buzzer of the car.

The buzzer of Maqueen V5 is connected to the P0 port of the microbit. If you want to use the P0 port, the buzzer switch needs to be in the off state.

Example 1: Play Music

6.5 Maqueen V5 go！

Example 1: Maqueen V5 go！

Program Description:

• Maqueen moves forward at a speed of 100. Also, it continuously plays music, and the car lights change color at a frequency of one second. The car lights are configured as RGB lights and can display seven colors.
• The speed range for moving forward is 0 - 255, not 0 - 100. This is also the range of the PWM pulse width.
• If the speed is within 30, the car may not move. Please set the speed to above 30. The reason is that the motor is driven by PWM. When the speed is low, the driving force will be insufficient. So when the speed is below 30, the driving force is too weak, resulting in the car hardly moving.

Example 2: Swing Car

Program Description:

• In this example, motor drive, car lights, and bottom RGB lights will be used.
• The bottom RGB lights will be lit in rainbow colors. The bottom RGB lights of Maqueen V5 are set at the P15 pin. The display range of rainbow colors is from 1 to 360. You can try adjusting the values to observe the color changes.
• The car will turn right for a while and then turn left for a while. The car lights on the left and right sides will also switch to different colors as well.

6.6 Quick Start for Line Tracing

Function Description

The quick line tracing function is a characteristic feature of Maqueen V5. It implements the line tracing function on the underlying chip. Students can use the line tracing function with just one "black", significantly lowering the entry threshold for students.

Example 1: Quick Line Tracing

Program Description:

• Quickly enable the line tracing function.
• After downloading the program and placing the car on the accompanying map, the car will automatically follow the black line to travel, as shown in the figure:

6.7 Ultrasonic Obstacle Avoidance

Function Description

On Maqueen V5, an ultrasonic sensor can be supported for installation. Through the detection of the distance of obstacles by ultrasonic waves, the function of automatic obstacle avoidance of the car can be realized.

Example 1: Ultrasonic Obstacle Avoidance

Insert the ultrasonic sensor into the ultrasonic interface at the front of the car. Both the front and rear rows of interfaces can be used, and there is no functional difference, as shown in the figure:

The situation when the ultrasonic sensor is inserted properly is shown in the figure:

After downloading the program, the car will automatically detect whether there are obstacles in the front. If so, it will automatically turn to avoid the obstacles.

Example 2: Assembly Line Robot

Function Description:

Place obstacles on the map as shown in the following figure.

After the program is downloaded, place the car on the black line. The car will travel along the black line. When encountering an obstacle in the front, the car will turn around and then continue to trace the line. This repeats all the time.

If the battery power is different and when the turning angle and speed are not appropriate, the speed of the motor and the pause time can be adjusted to improve the effect.

Note: If the detection distance of 10 cm in the program is too short and causes a collision, the distance value can be appropriately increased, such as 15cm-20 cm.

[图片]

6.8 Conventional Line Tracing Program

Function Description

Maqueen V5 is onboard with 3 line tracing sensors. When the black line is detected, the output state value is 1. When the black line is not detected, the output state is 0. Utilizing the sensitivity of the sensors to the black line, it is used for line tracing travel.

Meanwhile, the analog quantities of the 3 line tracing sensors can also be read.

Example 1: Line Tracing Robot

Program Description:

Realize the logic of line tracing by reading the states of the 3 line tracing sensors.

Program Link: https://makecode.microbit.org/_7WzMXpWXv7th

Example 2: Read the Analog Quantities of the Line Tracing Sensor

Program Description:

The function of the analog quantity value can be used to read different gray values on the map, and it is possible to judge whether the map material is suitable for line tracing through the ADC value.

This program demonstrates placing the car on a white background and a black background respectively, and checking the difference in gray values between the two.

Read the value of the analog quantity of the line tracing sensor and display it on the computer.

Data Results:

It can be seen from the data that on the black background, the gray value is about 2250, and on the white background, the gray value is about 3000. The numerical difference is about more than 700. Through the difference in values, it is possible to determine whether the car is currently on the white background or the black background, thereby realizing the function of line tracing.

You can also try to read the gray values on different backgrounds to see what kind of gray characteristics and differences there are between them. At the same time, it is also possible to judge whether the map material is suitable for line tracing through the ADC value.

6.9 Application of Light Sensor - Light-Avoiding and Light-Chasing Robots

Function Description

Maqueen V5 has a light sensor built in on each of the left and right sides at the front. This sensor can detect the intensity of light. By the difference in the intensity of light on both sides, the car can avoid the light or travel in the direction of the light.

The positions of the light sensors are shown as follows:

Example 1: The Robot That Avoids Light

Program Description:

• This example demonstrates that if there is strong light on one side during the driving process of the car, it will turn to avoid the light and drive.
• In actual tests, the flashlight function of the mobile phone can be used to shine on the light sensor to verify the program effect.

Program Link: https://makecode.microbit.org/_4FtRXhemt0Af

Example 2: The Robot That Tracks Light

Program Description:

• This example demonstrates that if there is strong light on one side during the driving process of the car, it will follow the direction of the stronger light to drive.
• In actual tests, the flashlight function of the mobile phone can be used to shine on the light sensor to verify the program effect.

6.10 Infrared Remote Control (The infrared remote controller is not configured by default)

Function Description:

Maqueen V5 has a built-in infrared receiving sensor, located in the center of the front of the car, which can receive the transmission signal from the infrared remote controller. By identifying the values of different buttons on the infrared remote controller, the car can perform different actions and be used for functions such as remote-controlling the robot.

Maqueen V5 does not come with an infrared remote controller by default. If you need to use this function, please contact the sales staff to purchase it separately. Moreover, the key values of infrared remote controllers in different batches may be different. Please be aware.

The following table shows the buttons of the infrared remote controller and the corresponding key values for your reference:

Example 1: Read the key value of the infrared remote controller

Program Description:

This example demonstrates displaying the received key value of the infrared remote controller on the serial monitor. The key value is displayed in decimal.

The example effect is as shown in the following figure:

Example 2: Infrared remote control car

Program Description:

• This program demonstrates controlling the car to move forward, backward, turn left, turn right, and stop using an infrared remote controller.
• Press the "2" key on the remote controller, the car moves forward; the "8" key for backward; the "4" key for left turn; the "6" key for right turn; and the "5" key for stop.

Program link: https://makecode.microbit.org/_cfkH1b0xgfkE

7. Calibration of the line-tracking sensor

The line-tracking sensor has been calibrated before leaving the factory. Usually, you don't need to calibrate it. If it is found that the line-tracking sensor cannot correctly recognize the black lines, you can try to calibrate the line tracking.

Before calibration, the microbit mainboard and the ultrasonic sensor need to be removed.

7.1 Place Maqueen on the black calibration area.

Make sure that all three probes are in the black area.

7.2 Press and hold the "Calc-Key" button for about 2 seconds. The line-tracking indicator light flashes twice. Then release the button and the calibration is completed.

7.3 Test the calibration result

Place the line-tracking sensor on the white background and the line-tracking indicator light goes off.

Place it on the black background and the line-tracking indicator light is on. The calibration is correct.

At this point, the calibration is completed.

Note: The line-tracking sensor uses the grayscale detection method to identify the black lines. Therefore, not all black lines can be effectively identified, and even calibration cannot ensure correct identification. For example, the map printed by the printer may not be identifiable.

8. Motor replacement method

Maqueen V5 adopts a design with replaceable motors. If the motor is damaged due to high-intensity use or being dropped, it can be replaced in the following way.

8.1 Remove the motor

8.1.1 Remove the two screws on the battery box

8.1.2 Unplug the power connection cable of the battery box

8.1.3 Remove the 4 motor fixing screws

8.1.4 Take out the motor and the buckle upwards

8.1.5 Take out the motor buckle in an inclined way

At this point, the motor disassembly is completed.

8.2 Install the motor

8.2.1 Insert the motor buckle in an inclined way to avoid the PCB solder joints

8.2.2 Press down gently to complete the installation of the buckle

8.2.3 Insert the motor with the buckle installed downwards into the motor interface

8.2.4 Screw on the 4 fixing screws on the back of the PCB

8.2.5 Plug in the connection cable of the battery box

8.2.6 Fix the 2 screws of the battery box

Note: The power cord of the battery box needs to be placed on the left side of the car to avoid the influence between the power cord and the wheels, as shown in the figure in the previous step.

8.2.7 Install the wheels

Note that the notch of the wheel needs to be aligned with the notch position of the motor shaft. Otherwise, it may not be installed correctly, or the wheel or the motor may be damaged.

At this point, the motor installation is completed.