INVENTOR S KIT MAKING A PEDESTRIAN CROSSING. FOR BBC micro:bit ADDITIONAL EXPERIMENT EXPERIMENT 11.

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1 INVENTOR S KIT FOR BBC micro:bit ADDITIONAL EXPERIMENT EXPERIMENT 11 MAKING A PEDESTRIAN CROSSING

2 11 EXPERIMENT ELEVEN MAKING A PEDESTRIAN CROSSING THE AIMS OF THIS EXPERIMENT ARE... To use six output pins to drive five LEDs and a buzzer To use the repeat loop To use the play tone block To learn how to setup initial LED states (outside of the main function loop) THE EXPERIMENT Using Block commands it is possible to control up to six outputs. This experiment will use all six to create a traffic light and pedestrian crossing demonstration. Five of the outputs will be used to drive LEDs, three of which will be used for the traffic light and two will be used for the stop and go indicators on the pedestrian crossing. The remaining output will be used to drive the piezo buzzer. This will all be controlled by a relatively simple sequence of Block commands. PARTS USED RED LED x2 47Ω RESISTOR x5 ORANGE LED x1 PIEZO ELEMENT BUZZER x1 GREEN LED x2 M/F JUMPER WIRE x7 2 EXPERIMENT 11 MAKING A PEDESTRIAN CROSSING

3 THE MICROSOFT BLOCK EDITOR This experiment is created using the Microsoft Block Editor. The Microsoft Block Editor is a drag and drop visual editor that provides a simple introduction to programming. Blocks snap together to build programs and are grouped by the type of function they do. When a group is selected the commands in that group are shown and can be selected. THE PROGRAM WILL NEED THESE BLOCKS... BASIC PAUSE INPUT ON BUTTON PRESSED LOOPS REPEAT TIMES MATHS 0 MUSIC PLAY TONE FOR PINS DIGITAL WRITE TO PIN USE THE BLOCKS DETAILED ABOVE TO CREATE THE CODE ON THE FOLLOWING PAGE 3 EXPERIMENT 11 MAKING A PEDESTRIAN CROSSING

4 This is the code that runs on start up. Run Compile Upload 4 EXPERIMENT 11 MAKING A PEDESTRIAN CROSSING

5 BUILD THIS CIRCUIT ON THE BREADBOARD V 0V 0V F G H I J R1 F G H I J + R3 R4 R5 + A B C D E R A B C D E LED 1 LED 2 LED 3 LED 4 LED 5 WHAT WILL HAPPEN? First of all the traffic light LEDs default to green and the pedestrian crossing LEDs default to red. When button A is pressed on the BBC micro:bit the traffic light LEDs go from green to amber to red. The pedestrian LEDs then change from red to green indicating that it is safe to cross, during which the buzzer beeps. After eight beeps the pedestrian LEDs change back to red and the traffic lights go through the red to red + amber to green sequence. This is now back at the original starting state. 5 EXPERIMENT 11 MAKING A PEDESTRIAN CROSSING

6 CIRCUIT DIAGRAM 6 EXPERIMENT 11 MAKING A PEDESTRIAN CROSSING

7 WHAT S GOING ON? The set digital write 1 to pin P12 and digital write 1 to pin P2 are used to set the initial LED states, which turn on the green traffic light LED and the red pedestrian crossing LED. These Blocks just execute once when the BBC micro:bit is turned on. The code then waits for button A to be pressed on the BBC micro:bit before executing the main loop of code. When button A is pressed the Blocks before the repeat loop execute causing the traffic light LEDs go from green to amber to red. The pedestrian LEDs then change from red to green indicating that it is safe for the pedestrian to cross. The pause blocks give the delays between each step of the sequence. The LEDs are connected as follows: TRAFFIC LIGHTS PEDESTRIAN CROSSING BBC micro:bit PINS RED P1 AMBER P8 GREEN P12 RED P2 GREEN P16 When it is safe to cross and the green pedestrian crossing LED is lit up and the buzzer then beeps eight times. This is controlled by the repeat loop. In each loop a tone is played and then there is a pause after each tone. 7 EXPERIMENT 11 MAKING A PEDESTRIAN CROSSING

8 After the beeps the next set of Blocks execute which change the pedestrian LEDs back to red and causes the traffic lights go through the red to red + amber to green sequence. This is now back at the original starting state and the code awaits another press of button A. Link to example code: EXTENSION TASKS Can you alter the tone of the beeps and how many times they are repeated? Try adding an image on the BBC micro:bit display when it is safe to cross the pedestrian crossing. THANK YOU This experiment was inspired by work produced by Thomas Stratford who 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. For up to the minute accounts of Thomas projects, follow him on Tom created his code using Touch Develop and more details can be found at: Every effort has been made to ensure that these notes are correct, however Kitronik accept no responsibility for issues arising from errors / omissions in the notes. Kitronik Ltd - Any unauthorised copying / duplication of this booklet or part thereof for purposes except for use with Kitronik products is not allowed without Kitronik s prior consent. 8 EXPERIMENT 11 MAKING A PEDESTRIAN CROSSING