Published March 14, 2022 © GPL3+

Smart Traffic Signal Light

Real traffic signal light managed with Raspberry Pi.

IntermediateProtip5,741

Things used in this project

Hardware components

Raspberry Pi 4 Model B

Traffic Signal Light

wire 1.5mm 10A (power cord)

Heatsink Case with Dual Fan

Story

This project aims to foster alternatives for traffic management with IoT. The traffic signal light runs at the power supply of 127V and 10A.

The prototype employs a Raspberry Pi 4 with the operating system Raspbian 2021. Tip: the Raspbian without GUI works, but it is a little more difficult to configure wireless, fan, and others. So, I prefer to install Raspbian with the GUI Desktop interface (Images are here).

1) Write the Raspbian image in a SD Card

To accomplish this step is necessary SD Card of 16GB+, and a SD Card software writer. I used win32diskimager software. My notebook has the port entry to write the card.

2) Hardware Configuration

2.1) Heat Sink issues: I experienced that basic heat sinks over CPU, RAM, Ethernet chip, and USB chip are sufficient to run Raspberry Pi 4 for relatively small loads. However, some researchers gives many reasons to buy a good cooler to avoid overheat at long runs with high loads. So, I replaced the basic heat sinks and put a single heatsink with dual cooler (yep, they do not assembly together).

2.2) Relay Shield: I put the relay shield over the heatsink with dual cooler. Unfortunately, the fan cable was not sized long. So, I put a jumper male-female and it works nice. The Figure 1 shows this assembly.

Figure 1 - Expanding the HeatSink Power Cable.

I put some wire connectors to avoid the small shield wiring ports, as shown in Figure 2. Probably there is a better way to insert these wires in this shield.

Figure 2 - Wire Connectors.

3. Software Configuration

3.1. In the first run, to access the Raspberry, I put in the terminal:

User:pi

Password:raspberry

3.2. The Internet Access through my SmartPhone

A small webserver was develop to manage the traffic light. So, it is necessary to configure the Internet acess to download some packages. I perform the wireless configuration doing my cellphone as access point for the Raspberry. A complete description is done here. In the terminal:

#rasp-config

> System Options - Wireless - SSID - no password

> Localization - BR - reboot

Then, after reboot, I turned on my cellphone access point router. Here, my SSID is AndroidAP. In the terminal, I confirmed that the wireless is running:

#iwlist wlan0scan | grep AndroidAP

Now I edited the file to maintain the connection after reboots:

#nano /etc/wpa_supplicant/wpa_supplicant.conf

This is the file contents:

ctrl_interface=DIR=/var/run/wpa_supplicantGROUP=netdev
update_config=1
country=BR
network={
ssid="AndroidAP"
psk=""
}

The 'psk' is the access point password. To avoid keep the raw password to every one, I encripted it as follows:

# wpa_passphrase"MY_PASSWORD" | tee -a /etc/wpa_supplicant/wpa_supplicant.conf >/dev/null

I update the field 'psk' in the "/etc/wpa_supplicant/wpa_supplicant.conf" file with the new encripted password.

Finally, I just run in the terminal:

# wpa_cli-i wlan0 reconfigure

(Tip: It is necessary to wait no more than 1 minute to verify it)

# ifconfig wlan0

#iwconfig

Then, the Raspberry is connected through the cellphone, and now I can download webserver files.

3.3 WebServer

Web.py is a small webserver. I installed it as follows:

sudo apt-get update
sudo apt-get install python-webpy

Next, I put the code of the "Software attached files" in my home folder.

A sample of the running is in the video 1.

A sample of the webserver running is in the video 2.

Code

#!/bin/python
#SemaforoTel: server
#Author: Lucio A. Rocha
#Last update: 25/02/2022-17:24

import web
import RPi.GPIO as GPIO
from time import sleep
from datetime import datetime
import sys
from os.path import exists
from os import remove

mySleep = 10

R1 = 19
R2 = 26
R3 = 20
R4 = 21

#Enable auto
cookie = "/home/pi/cookie.txt"

#Initialize the ports
t = ( R1, R2, R3 )
c = ( 'VERMELHO', 'AMARELO', 'VERDE' )

GPIO.setmode(GPIO.BCM)

for i in t:
	GPIO.setup(i, GPIO.OUT)
	GPIO.output(i,True) #disable port

render = web.template.render('/home/pi/templates/')
urls = (
	'/','index',
	'/update','update',
	'/auto','auto'
)

class index:
	def GET(self):
		GPIO.output(R1, True) 		
		GPIO.output(R2, True) 		
		GPIO.output(R3, True) 		
		
		if exists(cookie):
			remove(cookie)

		return render.index('')
class update:
	def GET(self):
		campo = int(web.input(led=0).led)
		if campo==1:
			GPIO.output(R1, False) #enable
			GPIO.output(R2, True) 
			GPIO.output(R3, True) 
		elif campo==2:
			GPIO.output(R1, True) 		
			GPIO.output(R2, False) #enable
			GPIO.output(R3, True)
		elif campo==3:
			GPIO.output(R1, True) 		
			GPIO.output(R2, True) 
			GPIO.output(R3, False) #enable
		else:
			GPIO.output(R1, True) 		
			GPIO.output(R2, True) 
			GPIO.output(R3, True) 

		if exists(cookie):
			remove(cookie)	
		return render.index(campo)

class auto:
	def GET(self):
		try:
			f = open(cookie,"w")
			f.close()

			while exists(cookie):
				j=0
				for k in t:

					#disable all
					for i in t:
						GPIO.output(i, True) #disable
					
					GPIO.output(k, False) #enable port
					print('[',str(datetime.now()),'] -> ',c[j],sep='')
					sleep(mySleep)
					GPIO.output(k, True) #disable port
					sleep(1)
					j=j+1
					if j>2: j=0
		except Exception as e:
			print('Error:',str(e))

if __name__ == "__main__":
	app = web.application(urls, globals())
	app.run()

#!/bin/python
#SemaforoTel
#Author: Lucio A. Rocha
#Last update: 25/02/2022-12:02

import RPi.GPIO as GPIO
import sys
from time import sleep
from datetime import datetime

GPIO.setmode(GPIO.BCM)

#args = sys.argv
#mySleep = int(args[1]) #Receive mySleep as argument
mySleep = 10

R1 = 19
R2 = 26
R3 = 20
R4 = 21

#Initialize the ports
t = ( R1, R2, R3 )
c = ( 'VERMELHO', 'AMARELO', 'VERDE' )
for i in t:
   GPIO.setup(i, GPIO.OUT)
   GPIO.output(i,True) #disable port

try:
   while True:
      j=0
      for i in t:
        GPIO.output(i, False) #enable port
        print('[',str(datetime.now()),'] -> ',c[j],sep='')
        sleep(mySleep)
        GPIO.output(i, True) #disable port
        sleep(1)
        j=j+1
        if j>2: j=0
finally:
   GPIO.cleanup()

#!/bin/python
# SemaforoTel
# Description: Stop semaforo running
# Author: Lucio A. Rocha
# Last update: 25/02/2022 - 13:16

import os, subprocess

#r = subprocess.run(['ps', 'aux'], stdout=subprocess.PIPE)
#print(r.stdout,'.')

# Try to kill 'semaforo_auto.py'
pid = subprocess.check_output('ps aux | grep semaforo_auto | head -n 1 | awk \'{print $2}\'', shell=True, text=True)
print('+SemaforoTel PID:',pid)

try:
	cmd = 'kill -9 ' + pid
	s = subprocess.check_output(cmd, shell=True, text=True)
	print(s)
except:
	print('No semaforo_auto.py active.')


# Try to kill 'servidor.py'
pid = subprocess.check_output('ps aux | grep servidor.py | head -n 1 | awk \'{print $2}\'', shell=True, text=True)
print('+Servidor PID:',pid)

try:
	cmd = 'kill -9 ' + pid
	s = subprocess.check_output(cmd, shell=True, text=True)
	print(s)
except:
	print('No servidor.py active.')

#Clean GPIO
import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BCM)

R1 = 19
R2 = 26
R3 = 20
R4 = 21

#Initialize the ports
t = ( R1, R2, R3 )

for i in t:
   GPIO.setup(i, GPIO.OUT)
   GPIO.output(i,True) #disable port

GPIO.cleanup()

$def with (campo)
<p align="center"><img src="static/logotipo.png" width="250px" height="150px"></p>
<pre align="center">Projeto SEMAFOROTEL</pre>

$if campo:
   <p align="center"><em>Active LED:</em> $campo</p>
$else:
   <p align="center"><em>Hello</em> SemaforoTel.</p>

<form align="center" action="http://localhost:8080/update">
	<input 	type="hidden"
		name="led"
		value="1">
	<input type="submit" value="VERMELHO" style="background-color:red;color:black;width:150px;height:40px;"/>
</form>

<form align="center" action="http://localhost:8080/update">
	<input 	type="hidden"
		name="led"
		value="2">
	<input type="submit" value="AMARELO" style="background-color:yellow;color:black;width:150px;height:40px;"/>
</form>

<form align="center" action="http://localhost:8080/update">
	<input 	type="hidden"
		name="led"
		value="3">
	<input type="submit" value="VERDE" style="background-color:green;color:black;width:150px;height:40px;"/>
</form>

<form align="center" action="http://localhost:8080/update">
	<input 	type="hidden"
		name="led"
		value="0">
	<input type="submit" value="APAGAR" style="background-color:white;color:black;width:150px;height:40px;"/>
</form>

<form align="center" action="http://localhost:8080/auto">
	<input 	type="hidden"
		name="led"
		value="0">
	<input type="submit" value="AUTOMTICO" style="background-color:aqua;color:black;width:150px;height:40px;"/>
</form>

<pre align="center"></pre>

Credits

lucio

0 projects • 0 followers

Smart Traffic Signal Light

Things used in this project

Hardware components

Story

2) Hardware Configuration

3. Software Configuration

Schematics

Wiring Schematic Diagram

Code

servidor.py

semaforo_auto.py

fim.py

index.html

Credits

lucio

Comments

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Smart Traffic Signal Light

Smart Traffic Signal Light

Things used in this project

Hardware components

Story

2) Hardware Configuration

3. Software Configuration

Schematics

Wiring Schematic Diagram

Code

servidor.py

semaforo_auto.py

fim.py

index.html

Credits

lucio

Comments

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