PJ001: External LED with Micro:bit

This project uses Micro:bit built-in button A/B to control external LED connected to pin 1, programmed by MakeCode blocks. The basic requirement is to on/off the LED, then there are several challenges for those who want to try further. Goals:

Digital signals and input/output basic understanding
LED as the typical simple digital output-er
Use digital signal from Micro:bit built-in button as input
Write digital signal to Micro:bit pin as output
Hardware: LED basic, pins and wiring
Software: if-else logic implicitly used

Homework Challenges:

Blink the external LED
Change the blinking speed with built-in button A/B. This involves variable exercise.

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Result Demo

Here is an example of the successful result done by our student.

PJ001: External LED with Micro:bit.mp4

Key Building Blocks for Programming

Voltage Signal Measurement

Discussion & Sharing

Parked Questions

Homework Challenge 1: Blink the External LED Forever

Homework Challenge 2: Blink the External LED, Started/Stopped by Button

Homework Challenge 3: Change the Blinking Speed by Button A/B

Homework Challenge 4: Change the Blinking Speed by Button A/B

Further Challenges

The Working Copy

Referred/Used By

Requirement

Hardware setup

Use Micro:bit built-in button A & B as digital signal input from user
Use Micro:bit pin 1 as digital signal output to drive external LED

Programming

Press built-in button A to light up the external LED, and
Press built-in button B to turn off the external LED

Effort Estimation

[x] Simple: 30-60 minutes

[ ] 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:

5-10 minutes: Understand requirement and solution, collect materials
10-15 minutes: Hardware setup and wiring
10-15 minutes: Programming, testing
10 minutes: Optional, measure the voltage of pin

Prerequisite

One should have prior knowledge

Micro:bit V2 board, Micro:bit pin breakout board, Breadboard: Know what they are, better to have prior experience using them
MakeCode by Microsoft, the programming tool, better to have prior experience using it with Micro:bit
LED basic what/how: Should be able to identify and connect the legs correctly
Resistor basic what/how: Just need to know what it is, better to know why we need it here, no need to know how to read the color rings
Digital signals, basic concept

Tools & Materials

A laoptop or tablet with internet access
1x Micro:bit V2 board , with USB cable
1x Micro:bit pin breakout board
1x breadboard
1x LED, random color
1x 220 Ω resistor
Some jumping wires

Hardware Wiring

Wiring scheme

This is what you need to build in a simplified view.

Use the micro:bit pin breakout and breadboard to connect the components, you don’t need to use the exact holes in the breadboard as others, as long as the wiring path is correct.

LED leads

LED's 2 lead are polarized! Recognized the difference, wire the "-" leg towards GND.

Learn more: LED basic what/how.

Key Building Blocks for Programming

Capture button input

This is an event triggered block, available to capture button events A/B/A+B

Input ->

Output digital signal to pin

To output a digital signal to a specific pin

Advanced -> Pins ->

Snippet: Button A part

This snippet is for button A, to trigger digital signal output as HIGH.

By this,

Voltage Signal Measurement

This is an optional task to measure the PIN 1 voltage level, so to enhance the understanding of voltage as signaling, and the digital signal output as voltage, and a special attention to digital signal as floating output.

Disconnect the PIN1 wiring, so it's not connected to anything
Use the same program, measure the PIN 1 voltage, observe and write down the value for
- Nothing pressing at the initial state
- button A pressing
- button B pressing
Take the test multiple times, think and analyze

PJ001-External-LED-with-Microbit-measure-digital-output-as-voltage.mp4

Discussion & Sharing

This optional part covers further competence development, in terms of testing, troubleshooting, analysis, documentation, flow chart diagrams practices, etc.

Presentation & Demo

Stand in front of the class, share with your group what you have made, please cover important points

Tell what it is your product
Demonstrate how it works
Explain how it works

Troubleshooting Stories

Share with your group about

What troubles you met
How you analyze
How you get help
How you solve it
What you have learnt

Circuit Wiring Diagram

Use your own way to visualize how the hardware components are connected by a free style drawing.

Visualize clearly the wiring path, mark clearly the pins and end points
So that your friends can follow this drawing to correctly reproduce the hardware setup

Any kind of children style drawing is OK! Here are some examples.

Flow Chart

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.

You might be interested to know what is "flow chart", click to learn more, but so far, it's not needed to be that serious, just draw something that can help you explain to your friends how the programming is made.

Knowledge Check

Tell us what is digital signal in your own way, explain how the digital signal as output happens in this project.
Can we connect LED to pin 0?

Parked Questions

These questions are out of scope for this project, but great to think about them, ask and discuss if you have enough effort

Why do we need a resistor with the LED? What if we remove the resistor?
How to read the resistor value by the color rings?

Homework Challenge 1: Blink the External LED Forever

So now, it should be not hard to try blinking the LED

Homework Challenge 2: Blink the External LED, Started/Stopped by Button

So now, it should be not hard to try blinking the LED

Homework Challenge 3: Change the Blinking Speed by Button A/B

Requirement:

Homework Challenge 4: Change the Blinking Speed by Button A/B

Requirement:

Further Challenges

If you get a quick done, do you dare to take further challenges? Those challenging points are independent, not related to one another

Change LED connection from pin 1 to pin 0, implement the same requirement
Implement the same requirement, but don't use "Input -> on button … pressed" block to get button input
Try next project PJ003: External LED + button with Micro:bit, variable usage
Try PJ006: Same 1 button to on/off external LED with Micro:bit with variable and boolean type logic
Try PJ011: Traffic Lights in Fixed Schedule

The Working Copy

Find out a working copy as a MakeCode shared project

PJ001: External LED with Micro:bit

Referred/Used By

Used in Session w16 of LP2415: 4 Weeks Refreshing Package, 24w15
Used in Session w46 of LP2346: 3 Weeks Recap & Review, 23w46
Used in LP2313: 10 Weeks Starting Package, 23w13

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