Night Safety Light

Living in Canada year round, we all know what’s like in the winter. Sun goes down by 4-5pm. The street can be dark and slippery. Can we make a wearable device with Microbit to help us be safe in the dark?

Dark street

Identify what features do you want?

Flashing LED when it’s dark.
Have an on/off button to save power
Only turn on when walking?
Display sensor measurement on button pressed?

Features on the Microbit

Light sensor, range 0 to 255. 0 is complete dark. 255 is super bright.
Acceleronmeter, tell us if we are moving.
Buttons, to navigate among features, or turn on/off LED. Typical uses:
- When button A is pressed
- When button B is pressed
- When button A+B are pressed together

Let’s know the sensors

LEDs, Light Emitting Diode

LEDs has become very common in our household. Usually the LEDs we saw are light bulb, like this one LED light bulb

On Microbit they look like these:

Surface Mount LEDs

Here is short video introduing LEDs by Microbit. YouTube Microbit LEDs

LEDs are small, effecient, bright, and don’t require much power
LEDs lights up when a one way electrical current pass through it
When we stop the electrical current, it takes time for the light to go away
- This time is related to strength of ambient light
- Microbit measure the time it takes for the LEDs to go out, and use that to estimate ambient light.

Here is another YouTube video that talks about using LED as light sensor. Have a look if you want to know more. They also shows a nice demonstration. Sparkfun using LED as light sensor

Design our program with flowchart

Before we start writing our code, we should first design our program. Creating a flow chart helps us to reduce bugs in our program, and also make it easier to spot them. We will do this step together in class.

Here are the basic element of flowchart flow chart

Below is an example of a simple flow chart Project flow chart

Build our code based on the flowchart design

In this project, I’ll ask you to use the While True block, instead of the built in Forever block, in order to practice our logical thinking. Here are some of the blocks:

While True Loop. Grap a while True...do... block from the Loops class

Block Python
For decision block, ie. if...else.... Grab an if...else... block from Logic class

Notice that you can expand or shink the if...else... with the + or - sign. You can also find

Block Python
To read estimated ambient light level, use the light level block from Input class

Block Python
If you want to add a button to your program, use button (A) is pressed block from the Input class

Block Python

Expand your if...else... block to include button feature.

Finishing Up

Find a way to put Microbit on your backpack, or wear it on your wrist.
Make a short video to demonstrate your work.
- Present the problem we are trying to solve
- What the solution is.

Here are some ideas to make microbit wearable.

Make, Code, Have Fun

This site was created to collect all of our project done in our coding class.