Project 05：Traffic Lights
Introduction
Traffic lights are closely related to people’s daily lives, which generally show red, yellow, and green. Everyone should obey the traffic rules, which can avoid many traffic accidents. In this project, we will use Raspberry Pi Pico and some LEDs (red, green and yellow) to simulate the traffic lights.
Components Required
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| Raspberry Pi Pico*1 | Raspberry Pi Pico Expansion Board*1 | Red LED*1 | Yellow LED*1 | Jumper Wires |
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| Green LED*1 | USB Cable*1 | 220ΩResistor*3 | Breadboard*1 |
Circuit Diagram and Wiring Diagram
Note:
How to connect an LED
How to identify the 220Ω 5-band resistor.
Test Code
The code used in this tutorial is saved in the file …\Python_Codes. You can move the code to anywhere,for example,we can save the Python_Codes file in the Disk(D), the route is D:\Python_Codes.
Open“Thonny, click“This computer”→“D:”→“Python_Codes”→”Project 05: Traffic Lights”. And double-click“Project_05_Traffic_Lights.py”.
from machine import Pin
import time
led_red = machine.Pin(16, machine.Pin.OUT) # create red led object from Pin 16, Set Pin 16 to output
led_yellow = machine.Pin(17, machine.Pin.OUT) # create yellow led object from Pin 17, Set Pin 17 to output
led_green = machine.Pin(18, machine.Pin.OUT) # create green led object from Pin 18, Set Pin 18 to output
while True:
led_red.value(1) # Set red led turn on
time.sleep(5) # Sleep 5s
led_red.value(0) # Set red led turn off
led_yellow.value(1)
time.sleep(0.5)
led_yellow.value(0)
time.sleep(0.5)
led_yellow.value(1)
time.sleep(0.5)
led_yellow.value(0)
time.sleep(0.5)
led_yellow.value(1)
time.sleep(0.5)
led_yellow.value(0)
time.sleep(0.5)
led_green.value(1)
time.sleep(5)
led_green.value(0)
5. Test Result：
Connect the pico board to the computer. Click
to check the Shell.
Click“
”, the code starts executing, what we will see are below:
1). First, the green light will be on for 5 seconds and then off;
2). Next, the yellow light blinks three times and then goes off.
3). Then, the red light goes on for five seconds and then goes off.
Repeat steps 1 to 3 above and press“Ctrl+C”or click“” to exit the program.
