PJ005: Digital Counter by Micro:bit

This project uses Micro:bit single board as a digital counter, uses built-in button A to increase counting, built-in button B to decrease counting, programmed by MakeCode blocks. The project contains a few tasks, it is suitable for junior learners for basic programming exercise. Goals:

Fun playing with Micro:bit to catch button pressed events and button status input
Practice of basic if-else logic, multiple branches
Basic usage of Variable (numeric integer type)

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PJ005_Digital_Counter.mp4

Effort Estimation

Prerequisite

Tools & Materials

Task 1: A Simple Counter with Max/Min Guards

Task 2: A Counter with Fast Forwarding/Backwinding

Task 3: Extended Learning and Exploring

Challenge 1: Add hinting/warning sound

Challenge 2: Improve user experience of button reactiveness

Challenge 3: Try different number displaying

Knowledge test, reflection and discussion

What are the matters?

Referred/Used By

Effort Estimation

[ ] Simple: 30-60 minutes

[x] Moderate: 1-2 hours

[ ] Challenging: more than 2 hours

The estimation bases on average situation without unexpected troubleshooting, assuming that the student meets prerequisites. It only indicates rough time needed to complete this project, but not about technical difficulty, not covering discussion and sharing time. Here is a possible breakdown:

30 minutes: Task 1
40-50 minutes: Task 2

Prerequisite

One should have prior knowledge

Tools & Materials

A laoptop or tablet with internet access
1x TM005: Micro:bit V2 board
MakeCode by Microsoft, the programming tool

Task 1: A Simple Counter with Max/Min Guards

Purpose: Learn "on button A/B/A+B pressed" event triggered blocks, learn variable range guarding

Requirement:

Click-press button A to increase by 1, safe guard max as 9
Click-press button B to decrease by 1, safe guard min as 0, no minus count
Click-press button A+B together to reset counter as 0
Optional hinting and/or warning sound on different situations

Test Cases:

Test with simulator in MakeCode and real target Micro:bit.

Test Case 1:
After starting or resetting, LED screen shows 0
Test Case 2.1:
Click-press button B, the counter should be increased by 1, the latest count is shown on LED screen.

Optionally, a short hinting sound is played on a valid count being increased.

Test Case 2.2:
Click-press button B many times until the counter reaches 9, then pressing button B should NOT change the counter any more, the count stays as max 9, shown on LED screen.

Optionally, a warning sound is played on an attempt to cross the max count.

Test Case 3.1:
Click-press button A, the counter should be decreased by 1, the latest count is shown on LED screen.

Optionally, a short hinting sound is played on a valid count being decreased.

Test Case 3.2:
Click-press button A many times until the counter reaches 0, then pressing button A should NOT change the counter any more, the count stays as min 0, shown on LED screen.

Optionally, a warning sound is played on an attempt to cross the min count.

Test Case 4:
Click-press button A+B together, the counter should be reset as 0, shown on LED screen.

Optionally, a warning sound is played on a successful resetting to 0.

Submit the Work:

Please submit your work to Google Classroom (here is a guide)

Basic Knowledge:

Catch button A/B/A+B pressing event triggering
Create a Variable to store the counting value

Examples & Tips:

You can check this "Counter" project from microbit.org as an starting example, remember that the features we need here are more than that.
Anothe example "counter lesson" by MakeCode

Prototype:

Here is a solution with "FIX ME" challenge, if you need a draft as a start

Task 2: A Counter with Fast Forwarding/Backwinding

Purpose: Learn using button A/B/A+B status, handle long pressing situation

Requirement:

Keep the same existing features of Task 1, adding below
- When Long-pressing button B, the counter should keep increasing continuously, the latest count is shown on LED screen, when releasing button B, the increasing stops. Still max guarded as 9.
- When Long-pressing button A, the counter should keep decreasing continuously, the latest count is shown on LED screen, when releasing button A, the decreasing stops. Still min guarded as 0.

Test Cases:

Test with simulator in MakeCode and real target Micro:bit.

The Test Cases of Task 1 are still valid, adding below

Test Case 2.3:
When Long-pressing button B, the counter should keep increasing by 1 and show the new count on LED screen. The max 9 should still be guarded. When releasing button B, the increasing should stop.
Test Case 3.3:
When Long-pressing button A, the counter should keep decreasing by 1 and show the new count on LED screen. The min 0 should still be guarded. When releasing button A, the decreasing should stop.

Submit the Work:

Please submit your work to Google Classroom (here is a guide)

Basic Knowledge:

Catch button A/B/A+B pressing status
Create a Variable to store the counting value

Prototype:

Here is a solution with "FIX ME" challenge, if you need a draft as a start

Task 3: Extended Learning and Exploring

Purpose: Creative task for your ideas, as an optional challenge task

Challenge 1: Add hinting/warning sound

Add different sound effects when increasing/decreasing the count, when hitting the max/min boundary.

Challenge 2: Improve user experience of button reactiveness

If you notice, the button pressing is a little tricky, especially in Task 2, the button A+B will be missed sometimes, because when the if-evaluation happens, it's hard to ensure both button A and B are already pressed, there could be a little time-gap, you can improve the reactiveness by adding a little delay between checking the A and B status...

Challenge 3: Try different number displaying

As you notice, starting from number 10, the LED screen displaying will have a scrolling, and it's slow animation. There are different ways to show a number, e.g. using the dots, and level bars. There are also some extensions for your exploration, search the extensions by keyword "number", you can get at least 2 interesting options.

Further Challenges

Make a beep sound reminder if the counting result becomes full 10, 100, 1000, note that the beep should happen just once when hitting the full counting, but not keep beeping all the time.
Energy saving mode: When there is not many visitors coming, the counter will be idle for some time, so there is a need to save energy, don't display the counter figure all the time, instead, display it when shaking the Micro:bit, after 3 seconds, turn off the display

Knowledge test, reflection and discussion

Purpose: Enhance basic knowledge understanding, reflect and summarize what we have learnt

Knowledge Check

How do we catch "button pressed" events? Is it triggered when pressing down, or releasing, or?
How do we get "button status" input? What is the value of it in the programming?
What are the difference between event triggering and status input?

Tips: Review knowledge from here if needed

KB007: Variable Basic Concept

Flow Chart

This project is a good example to practice flow chart drawing! Use your own way to visualize how the programming controlling logic is done, by a free style drawing, so that your friends can follow this flow-chart to reproduce the programming.

Review and discuss

Follow the tutor to take 5-10 minutes to review the questions and answers, correct some possible misunderstood issues or faults

Reflect for findings and questions!

Take 1-2 minutes to explore anything on the tools and the making flow, with curiosity, no matter how much prior knowledge you have, you should make

At least 1 interesting finding
At least 1 curious question

What are the matters?

Here are some incomplete or buggy work by others, could you analyze and point out what are the matters?

An attempt for Task 1

Referred/Used By

Used in LP2313: 10 Weeks Starting Package, 23w13
Used by LP2517: Special Onboarding Workshop, 25w17
Used by LP2520.B: Start A Bit Programming, 25w20

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