Sunday, 20 September 2020

Controlling a Robotic Arm with a Microbit

 

Robotic arm

This project uses a Robotic Arm from Jarcar with a custom made Microbit interface, to enable the arm to be controlled by the Microbit.


Coding in MakeCode

This starter project is recommended for primary school students to make the coding easier so students can focus on the algorithms and actions. It provides functions that can be called to run the motors, buzzer and LEDs.

https://makecode.microbit.org/_UgiH2uXFDKma

When the page open, click Edit Code to access the coding page. To use the function blocks, click Advanced and then Functions

Just before each function block you need a time block. To find the time block, click variables and then set time to ...

Here is an example of using a function. When button A is pressed, the time is set to 2000 ms (which is 2 seconds) and motor 2 will move upwards for 2 seconds.




Function

Action

Each action is stopped after the specified time

call m1Open

Opens the jaws of the gripper

call m1Close

Closes the jaws of the gripper

call m2Up

Moves the “wrist” part of the arm upwards

call m2Down

Moves the “wrist” part of the arm downwards

call m3Up

Moves the “elbow” part of the arm upwards

call m3Down

Moves the “elbow” part of the arm downwards

call m4Up

Moves the base part of the arm upwards

call m4Down

Moves the base part of the arm downwards

call m5Right

Rotates the base part of the arm to the right

call m5Left

Rotates the base part of the arm left

call forward

Uses motor 3 and motor 4 together, to move the arm forwards

call backward

Uses motor 3 and motor 4 together, to move the arm backwards

call redLight

Turns on the red LED. (Recommended for the On Start block, to show that the Microbit is on.)

call greenLight

Turns on the green LED.

call searchlight

Turns on the LED on the arm.

call buzzer

Turns on the buzzer. (Note that he music blocks also work and give a wider range of sounds.)



Coding in Javascript or Python

You can use this pin allocation table to plan your algorithm.

Pin Allocations

Micro:bit Pin

Action

Pin setting

O

Buzzer

0 = off, 1 = on or use Music blocks.

1

Red LED

0 = off, 1 = on

2

Green LED

0 = off, 1 = on

3

M1, Gripper

0 = off, 1 = on

4

M1, Gripper

0 = open, 1 = close

6

M2, Wrist

0 = off, 1 = on

7

M2, Wrist

0 = down, 1 = up

8

LED “search light”

0 = off, 1 = on

9

M3, Elbow

0 = off, 1 = on

10

M3, Elbow

0 = down, 1 = up

13

M4, Base motion

0 = off, 1 = on

14

M4, Base motion

0 = down, 1 = up

15

M5, Base rotation

0 = off, 1 = on

16

M5, Base rotation

0 = clock-wise, 1 = counter click-wise

Controlling a Robotic Arm with a Microbit

  This project uses a Robotic Arm from Jarcar with a custom made Microbit interface, to enable the arm to be controlled by the Microbit . C...