BBC micro:bit Pedestrian Crossing Project

This Pedestrian Crossing project was submitted to us by Thomas Stratford. Thomas started this project to try out the pre-written code that came with the IET Pedestrian Crossing resource. The aim is to use the BBC micro:bit to develop a prototype for a pedestrian crossing for a local secondary school.   Thomas Stratford is an ICT Technician for the Misbourne School. When he isn't fixing IT problems, he spends his time making, tinkering and building Electronics projects. He is currently learning about the recently released BBC micro:bit.

BBC micro:bit Pedestrian Crossing Project:

In order to create this project in the same way as the example below, you will need to source the following components: Parts List:

• A BBC micro:bit.
• 1 x Kitronik Prototyping System.
• 2 x Red LED’s.
• Two Green LED’s.
• An Orange LED.
• 1 x Piezo Sounder.
• A x NPN Transistor.
• 1 x 2.2kΩ Resistor.
• 5 x Resistors suitable for your LED’s (I used 220Ω resistors).
• 7 x M/F Jumper wires.
• 3 x M/M Jumper wires.

Note: With the exception of the 5 x 220Ω resistors, all of the parts used used in this Project can be found in the Kitronik Inventors Kit. If you have the Inventors Kit you can substitute the 220Ω resistors for the 47Ω resistors that come with the Kit.

Stage 1 - The Traffic Lights:

First, I connected three LED’s to P0, P1 & P2 via series resistors as show in the picture below. Stage 1 Suggested Breadboard Layout:

 

BBC micro:bit Edge Connector Breakout Board	Breadboard Connection
P0 pin	Red Traffic LED via 220Ω Resistor.
P1 pin	Orange Traffic LED via 220Ω Resistor.
P2 pin	Green Traffic LED via 220Ω Resistor.
0V Pin	Breadboard negative rail.
3V Pin	Breadboard positive rail.

  Stage 1 Completed Example:

Stage 2 - Adding Pedestrian Crossing LEDS:

This worked well so I thought I would try adding two more LED’s via series resistors to ports (P8 & P12). I modified the pre-written program so that the two additional LED’s would also be controlled.

Stage 2 Suggested Breadboard Layout:

 

BBC micro:bit Edge Connector Breakout Board	Breadboard Connection
P0 pin	Red Traffic LED via 220Ω Resistor.
P1 pin	Orange Traffic LED via 220Ω Resistor.
P2 pin	Green Traffic LED via 220Ω Resistor.
P8 pin	Green Pedestrian LED via 220Ω Resistor.
P12 pin	Red Pedestrian LED via 220Ω Resistor.
0V Pin	Breadboard negative rail.
3V Pin	Breadboard positive rail.

  Stage 2 Completed Example:

Stage 3 - Adding The Crossing Beeper:

The final part of this project was to add a piezo sounder to simulate the crossing beeper. I connected a piezo sounder to port (P16) via a driver transistor. I modified the code once more to add this functionality.

Stage 3 Suggested Breadboard Layout:

 

BBC micro:bit Edge Connector Breakout Board	Breadboard Connection
P0 pin	Red Traffic LED via 220Ω Resistor.
P1 pin	Orange Traffic LED via 220Ω Resistor.
P2 pin	Green Traffic LED via 220Ω Resistor.
P8 pin	Green Pedestrian LED via 220Ω Resistor.
P12 pin	Red Pedestrian LED via 220Ω Resistor.
P16 pin	2.2kΩ Resistor for Transistor.
0V Pin	Breadboard negative rail.
3V Pin	Breadboard positive rail.

  Stage 3 Completed Example:

Note: The Breadboard layout shows a buzzer with leads but the completed example shows a buzzer that fits directly to the breadboard, therefore the wire link or jumper wire is connected differently. It would be better to follow the breadboard image layout as this is easier to follow. Code: The original code was written in Microsoft Touch Develop. This editor has since been taken out of commission and the code has been recreated in the Microsoft MakeCode editor, see below.   We would like to thank Thomas for sharing his excellent project with us. For up to the minute accounts of Thomas' projects, follow him on Twitter: @MrTomsWorld

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