Microbit handle control

1. Learning objectives

In this course, we mainly learn how to use MakeCode graphical programming to realize the microbit handle to control the creeping car.

Principle of creeping car movement:

The friction of the front wheel is changed by adjusting the 1# bolt connection buckle ratchet to control the forward direction of the car. When the 1# bolt connection is located in front of the 24-tooth gear, the front wheel can only move forward, so the car creeps forward; when the 1# bolt is connected to the back of the 24-tooth gear, the front wheel can only move backward, and the car creeps backward.

2. Building blocks

For detailed steps of building blocks, please refer to the installation drawings of [Assembly course]-[Unicycle] in the materials or the building block installation album.

After assembly, the frame of the creeping car needs to be adjusted to the closed state.

! Special Notes:

Place the two ratchets in front of the 24-tooth gear so that the crawler can move forward.

Place the two ratchets behind the 24-tooth gear so that the crawler can move backward.

3. Motor wiring

Insert the motor wiring on the left side of the car into the M1 interface of the Super:bit expansion board, with the black line close to the battery side;

As shown below:

4. Programming

Method 1 Online programming:

First, connect micro:bit to the computer via a USB data cable. The computer will pop up a U disk. Click the URL in the U disk: https://makecode.microbit.org/ to enter the programming interface. Then, add the Yahboom software package to start programming.

Method 2 Offline programming:

Open the offline programming software MakeCode and enter the programming interface. Click [New] and add the Yahboom software package to start programming.

superbit kit expansion package: https://github.com/YahboomTechnology/SuperBitLibV2 handle expansion package: https://github.com/YahboomTechnology/GHBitLib

4.1 Add expansion package

4.2 Blocks used

The location of the blocks required for this programming is shown in the figure below.

4.3 Add new variables

① Find the [Variable] option in the building block bar ---- [Make a Variable]

② Enter the variable name to complete the new variable.

4.4 Combined blocks

The microbit summary program on the squirm car is shown in the figure below

The handle joystick control program is as follows

The handle gravity control program is as follows

You can also directly open the microbit-handle-control-Unicycle-code.hex, microbit-microbit-Handle-rocker-control.hex, microbit-Handle-gravity-control.hex files provided in this experiment and drag them into the browser that opens the URL, and the program diagram of this project source code will be automatically opened

5. Experimental phenomenon

We need to download the program of the peristaltic car to the micro:bit motherboard of the peristaltic car, turn on the power switch of the peristaltic car, and we can see that a heart pattern will be initialized on the micro:bit dot matrix.

Download the handle remote control program to the micro:bit motherboard of the handle, turn on the power switch of the handle, and we can see that a heart pattern will be initialized on the micro:bit dot matrix, and then an "X" pattern will be displayed, indicating that the handle is in the default state and no data is sent.

The two will automatically complete the pairing, and then we can start remote control of the peristaltic car.

The functions of the handle are as follows.

Handle joystick control:

After the handle and the creeper car are paired successfully, we can see that the number 1 is displayed on the micro:bit dot matrix of the creeper car, indicating that it is in mode 1 at this time.

In mode 1:

• Push the joystick forward to control the movement of the creeper car, and it will stop when you release your hand;
• Press the red button to light up the red RGB light;
• Press the green button to light up the green RGB light;
• Press the yellow button to light up the yellow RGB light;
• Press the blue button to light up the blue RGB light.

We can press the joystick to switch to mode 2. At this time, we can see that the number 2 is displayed on the micro:bit dot matrix of the creeper car, indicating that it is in mode 2.

In mode 2:

• Push the joystick forward to control the movement of the peristaltic car, and it will keep rotating when you release your hand;
• Press the red button to light up the red RGB light and stop the moving peristaltic car;
• Press the green button to light up the green RGB light;
• Press the yellow button to light up the yellow RGB light;
• Press the blue button to light up the blue RGB light.

Each time you press the joystick, it will switch back and forth between mode 1 and mode 2, and the RGB light will go out.

Handle gravity control:

After the handle and the peristaltic car are successfully paired, we can see that the number 1 is displayed on the micro:bit dot matrix of the peristaltic car.

• Tilt the handle forward to control the movement of the peristaltic car, and stop the movement when placed horizontally;
• Press the red button to light up the red RGB light;
• Press the green button to light up the green RGB light;
• Press the yellow button to light up the yellow RGB light;
• Press the blue button to light up the blue RGB light.

(Note: There is only one mode for handle gravity control, and mode 2 cannot be switched)