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.

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