Last lesson, we learned to control a single DC motor with a fan as the carrier. This lesson, we will learn TT motor knowledge, achieves coordinated complex control of multiple motors, makes a simple car, and enables its straight driving and steering.
Project Objectives
Knowledge Objectives
1.Understand TT motor concepts.
2.Understand differences between TT & DC motors.
3.Master general motor control methods for UNIHIKER K10.
Practical Objective
Make a simple car with cardboard: driven by motors, the car is assisted to move straight, turn left/right; and the screen displays corresponding road sections.
Materials List
Preparations
Hardware
(1) Connect two TT motors to expansion board motor ports M1/M2 via DuPont lines respectively; note the positive and negative polarities.
(2)Insert UNIHIKER K10's edge connector connector vertically into expansion board's Micro:bit connector (align correctly).
(3) Connect UNIHIKER K10 and the expansion board to the computer via USB data cable and expansion board power cable (UNIHIKER K10 only needs to be connected for uploading ), then toggle the expansion board power switch to ON.
Note: UNIHIKER K10 has an operating voltage of 3.3V, while the motor has an operating voltage of 3–7.5V (rated at 6V). UNIHIKER K10 cannot power the motor normally,.So, connect the expansion board to an external power supply (e.g., computer), or use a power bank for cable-free, portable car operation.
Car Assembly
Cut and assemble the cardboard according to the figure below, then load the motors into the car and connect them to the rear wheels accordingly.
(1) Car body cardboard thickness: 2–3 cm; tire cardboard thickness: approx. 5 cm. Unit: cm.
(2) Install rear wheels after connecting to motors; connect front wheels with a straw/short wooden stick, fasten to car bottom with thin string.
Complete assembly drawing of the car is as follows:
Connect expansion board to power bank, place inside the car via the top opening.
Software
Open Mind+ v2, switch to“Upload Mode”, connect the UNIHIKER K10 as shown in the figure below, and load the UNIHIKER K10 library.
Hands-on Practice
Next, we will use the expansion board and motors to enable the driving function of the simple car.
Task 1: Straight Driving
In this task, control the motors to make the car move forward and backward, and the UNIHIKER K10 screen displays the straight driving section.
Task 2: Car Turning
In this task, control the motors to realize the car's turning function, and the UNIHIKER K10 screen displays the corresponding turning section.
Task 1: Straight Driving
Code
STEP1: Load the expansion board
Click "Extension", find the "motor:bit" under "Module" and click it to complete the addition.
STEP2：Car Forward/Backward
To implement the forward/backward functions of the car, we need to use the "motor(M1) rotate(CW) at speed(200)" block under the "motor:bit" , as shown in the figure below:
To enable the car to autonomously stop after traveling a certain distance, we need to use the "motor(M1)stops" block under the "motor:bit" , as shown in the figure below:
Since the two motors are mounted symmetrically, to make the car move straight forward/backward, the motors need to run at a consistent speed with opposite rotation directions. The specific rotation direction settings shall be determined based on the physical orientation of the motors.
The complete program code is shown below:
To make the car move backward, you only need to reverse the rotation directions of M1 and M2.
Run the Code
Click the“Upload”buttonand wait for the upload to complete. Then disconnect the UNIHIKER K10 from the computer, turn on the power switch of the expansion board, and you will observe that the car moves straight for a certain distance and then stops.
Code Review
Category | Blocks | Function |
 |  | Motor speed/direction control: Select M1-M4/All, speed 0-255; direction: Forward/Reverse. |
 | Motor stop control: Stop current rotation; "All" mode stops all associated motors together. |
Task 2: Car Turning
Code
Car turning is caused by different rotation speeds of the two motors. Take left turn as an example: M2 (right rear wheel) :normal speed; M1 (left rear wheel) :slow down/stop → right wheel faster (more power), left wheel slower/stationary → car turns left.
When writing the program, you only need to modify the speed of the corresponding motor(s). As for the specific speed difference between the two motors required to achieve a specific turning angle, it is related to the size of the car. You can modify the data and test it by yourself to achieve the target function.
The complete program code is shown below:
Run the Code
Click the“Upload”button, wait for the upload to complete,then disconnect the UNIHIKER K10 from the computer, turn on the power switch of the expansion board, and you will observe that the car turns 90° and then stops.
(1) Front wheels are driven wheels: placing the power bank inside the car exerts pressure on them, increasing the difficulty for rear wheels to drive front wheels and affecting the normal driving path. Recommend a lighter power bank and place it at the car’s rear.
(2) During car movement: ensure module connecting wires do not block wheels, otherwise car operation may be affected.
Knowledge Base
Next, let's learn and summarize the hardware knowledge used in this lesson.
The Concept of the TT Motor
The TT motor is a micro DC gear motor, with the full names being "TT Motor" or "TT DC Dual-shaft Gear Motor". It is usually composed of a small DC motor and a reduction gearbox.
Core Structure.
Function Description | Function Description |
DC Motor Body | The core power unit, usually a micro DC motor. It generates rotational power when energized and provides the basic driving force for the entire motor. |
Reduction Gearbox | Equipped with a built-in set of inter meshing gears. Its core function is to reduce the rotation speed and simultaneously amplify the rotational force (torque), enabling the motor to drive heavier loads. |
Output Shaft | A power transmission component, available in single-shaft or dual-shaft designs. It transmits the low-speed and high driving force processed by the gearbox outward and ensures stable power output. |
Differences Between TT Motor and Ordinary DC Motor
Comparison Dimension | TT Motor | Ordinary DC Motor |
Core Structure | DC motor + built-in reduction gearbox | Motor body only, no reduction device |
Output Characteristics | Slow rotation but high torque (Rotation speed reduced by tens to 200 times, with rotational torque amplified synchronously); can drive light loads without additional reduction equipment | High rotation speed but low torque (like a high-speed rotating small fan); unable to drive light loads independently |
Applicable Scenarios | Smart cars, toy models, DIY small devices, educational robots (all for lightweight application requirements) | Electric fans, electric toothbrushes, handheld vacuum cleaners, power bank fans, small blenders, etc. |
Durability | Suitable for intermittent operation; prone to wear under long-term high-intensity operation (medium service life) | More robust structure, strong stability during continuous operation, and better durability |
* TT motor: low rotation speed, high torque → suitable for load-driving scenarios;
* ordinary DC motor: high rotation speed, low torque → suitable for high-speed light-load scenarios.
Challenge Task
School’s "Mini Logistics" experience program: Control the car to finish the simulated delivery task from Teaching Building Area A to Playground Equipment Room (route see figure below, unit: m). Stop for 3 seconds at the library entrance to check no cargo falling off (simulates actual delivery verification).
Tip: The screen of UNIHIKER K10 shall display the following content in sequence: "Departure from Starting Point → Straight Section → Right Turn Section → Passing Stop → Straight Section → Left Turn Section → Arrival at End Point". During the stop, the additional text "Verify Cargo" shall be displayed.
Task 1 (1)Car Forward.zip 
