Project 19 BT Controls Robot Arm

image-20251203112801636

1. Description

In this project, we will combine the BT APP and the BT on Micro:bit to realize multiple functions of the robot arm.

2. Wiring Diagram

Servo

Function / Position

Shield Port

Brown Wire

Red Wire

Orange Wire

Servo 1

Right

Micro:bit 16-channel Servo Shield

G

V

S(4)

Servo 2

Base Rotation

Micro:bit 16-channel Servo Shield

G

V

S(5)

Servo 3

Claw

Micro:bit 16-channel Servo Shield

G

V

S(6)

Servo 4

Left

Micro:bit 16-channel Servo Shield

G

V

S(7)

img

3. Preparations

  1. Install the Micro:bit: Insert the Micro:bit mainboard into the robot arm’s 16-channel servo shield.

    • Note: Ensure the Micro:bit’s LED matrix is facing the correct direction (usually matching the silk screen markings on the shield).

  2. Connect Power: Connect the external power source (battery pack or DC adapter) to the shield, and turn on the power switch on the shield.

  3. Connect to PC: Connect the Micro:bit to your computer using a Micro USB data cable.

    • Check: You should see a drive named “MICROBIT” appear on your computer.

  4. Launch Software: Open the MakeCode editor.

    • Web Version: Visit https://makecode.microbit.org/

    • Offline Version: Launch the MakeCode Offline App if installed.

drag the code manually (add the pca9685 extension library first).

Add the pca9685 Extension Library

  1. Open Settings → Extensions.

  2. Input the link:

    https://github.com/keyestudio2019/pxt-pca9685-smallest

    image-20251203162506704

  3. Search, download, and install the extension.

  4. After installation, you’ll find the pca9685 extension library on the left.

4. Test Code

To import the Hex file directly, please locate the downloaded Hex file and drag it into the editor.

🏡Click to download the code for this lesson

After downloading the code, simply drag it directly into the coding area to upload it.

(Note: The image below is for demonstration purposes only—please drag in the code you downloaded for this lesson above.)

image-20251203134322106

5. Test Result

(1) Project Settings

Tap Settings → Project Settings, enter “BT Controls Robot Arm”, and set “No Pairing Required” to ON.

(Not required if importing the provided code directly.)

image-20251203163611609

(2) Download & Connect

  1. Download code to the Micro:bit mainboard and connect external power.

  2. Open the “keyes arm” APP and connect via Bluetooth (refer to Project 18: Read BT Data).

  3. Use the APP buttons to control the robot arm.

7.Functions of Buttons

img

Connect the APP to the Bluetooth of the microbit mainboard

img

Disconnect the Bluetooth

img

Press:“F”—>The big pendulum connected to servo 4 swings forward

Release:“S”—->The big pendulum connected to servo 4 doesn’t move

img

Press:“L”—>The robot claw will open

Release:“S”—>The robot claw will not move

img

Mode: 1

img

Press:“R”—>The robot claw will close

Release:“S”—>The robot claw will not move

img

Press:“B”—>The big pendulum connected to servo 4 swings backward

Release:“S”—>The big pendulum connected to servo 4 doesn’t move

img

Press:“f”—>The small pendulum connected to servo 1 swings backward

Release:“S”—>The small pendulum connected to servo1 will not move

img

Press:“l”—>Servo 2 turns left

Release:“S”—>Servo 2 will not rotate

img

Mode: 2

img

Press:“r”—>Servo 2 turns right

Release:“S”—>Servo 2 will not rotate

img

Press: “b”—>The small pendulum connected to servo 1 swings forward

Release:“S”—>The small pendulum connected to servo 1 will not move