Joppe SmeetsPieter Luyten
Published © GPL3+

Traffic Light Information System

Traffic Light Information System that lets the driver know at which speed he needs to drive in order to pass the green light.

AdvancedFull instructions provided22,671
 Traffic Light Information System

Things used in this project

Hardware components

Arduino Yun
Arduino Yun
×1
Arduino UNO & Genuino UNO
Arduino UNO & Genuino UNO
or any other Arduino board
×1
Ultrasonic Sensor - HC-SR04 (Generic)
Ultrasonic Sensor - HC-SR04 (Generic)
×1
DS3231 RTC
Real Time Clock
×1
LED (generic)
LED (generic)
1 x Red LED, 1 x Yellow LED, 1 x Green LED
×3
Resistor 330 ohm
Resistor 330 ohm
×3
433 MHz modules
1 x Transmitter, 1 x Receiver
×1
Android device
Android device
×1
SD Card
×1
IOTOPIA Rapid Development kit
AllThingsTalk IOTOPIA Rapid Development kit
×1
Jumper wires (generic)
Jumper wires (generic)
×1

Software apps and online services

Arduino IDE
Arduino IDE
Android Studio
Android Studio
MySQL database hosting service

Story

Read more

Schematics

Schematic: Arduino Transmitter

RF 433MHz module:
tx_pin --> pin 3

HC-SR04 module:
trig_pin --> pin 5
echo_pin --> pin 6

Schematic: Arduino Yun Receiver

RF 433MHz module:
rx_pin --> pin 3

TrafficLight (3 LEDs):
RedLED --> pin 5
OrangeLED --> pin 6
GreenLED --> pin 7

DS3231 (Real-Time-Clock):
SCL --> SCL (pin 3 on Arduino Yun)
SDA --> SDA (pin 2 on Arduino Yun)

Code

Arduino Transmitter Code

Arduino
/*   IOTOPIA - 2016-2017 - Traffic Light Information System (Transmitter)  
 * by Pieter Luyten & Joppe Smeets   
 *    
 * Send distance to another arduino via RF 433MHz modules
 * 
 * RF 433MHz module:
 *    tx_pin  --> pin 3
 *    
 * HC-SR04 module: 
 *    trig_pin  --> pin 5
 *    echo_pin  --> pin 6
 *    
*/

#define tx_pin 3
#define trig_pin 5
#define echo_pin 6

#include <VirtualWire.h> // Library for RF 433 MHz modules
 
#include "HCSR04.h" // Library for HC-SR04 module
HCSR04 ultrasonic(trig_pin,echo_pin); 

int distance;

char CharMsg[21];


void setup() {
  Serial.begin(9600); 
  vw_setup(2000); // Bits per sec
  vw_set_tx_pin(tx_pin);
}

void loop() {

  distance = ultrasonic.Ranging(CM); // Measure the distance in cm

  while(distance < 0){ // Avoid false readings, measure the distance again
      distance = ultrasonic.Ranging(CM); 
  }
  
  sprintf(CharMsg, "%d,", distance);
  vw_send((uint8_t *)CharMsg, strlen(CharMsg)); // Send the distance
  vw_wait_tx(); // Wait until the whole message is gone

  Serial.print("Distance (cm):  ");
  Serial.println(distance);
  delay(250);

}

Arduino Receiver & MySQLdb

Arduino
/*   IOTOPIA - 2016-2017 - Traffic Light Information System  (Receiver + Upload to MySQLdb)
 *  by Pieter Luyten & Joppe Smeets
 *
 *  Receive distance from another arduino via RF
 *  Upload traffic light data and distance to MySQL database
 *
 *  RF 433MHz module:
 *     rx_pin  --> pin 3
 *
 *  TrafficLight (3 LEDs):    
 *     RedLED  --> pin 5
 *     OrangeLED  --> pin 6
 *     GreenLED  --> pin 7
 *
 *  DS3231 (Real-Time-Clock):
 *     SCL --> SCL (pin 3 on Arduino Yun)
 *     SDA --> SDA (pin 2 on Arduino Yun)
 *
 *  SD Card - Arduino Yun
 *     SD Card (with PHP-file)--> integrated SD slot
*/

#define RedLED  5
#define OrangeLED  6
#define GreenLED  7

#define rx_pin 9

#include <VirtualWire.h> //  RF 433 MHz modules
#include <TimeAlarms.h> //  Alarms
#include <Wire.h> //  I2C communication
#include "RTClib.h" //  Real Time Clock
#include <Process.h> // Run Linux processes on the AR9331

// UnixTime: Time, defined as the number of seconds that have elapsed since 1 January 1970
long UnixTime_green_1; // Next green light (in UnixTime)
long UnixTime_red_1; // Next red light (in UnixTime)
long UnixTime_green_2; // Next but one green light (in UnixTime)
long UnixTime_red_2; // Next but one red light (in UnixTime)
long s_till_orange; // Seconds till orange

RTC_DS3231 rtc;

char StringReceived[22];

boolean i;

int interval = 5; // in seconds
int distance; // in cm

void setup() {
  rtc.begin();
  //rtc.adjust(DateTime(F(__DATE__), F(__TIME__)));
  Serial.begin(9600);
  Bridge.begin(); // Initialize Bridge

  
  vw_setup(2000); // Bits per sec
  vw_set_rx_pin(rx_pin);
  vw_rx_start();
  
  Alarm.timerRepeat(interval, UpdateTrafficLData); // Update traffic light data (next green/red light ... )
  Alarm.timerRepeat(1,PrintCurrentTime); // Print current time every x seconds

  pinMode(GreenLED, OUTPUT);
  pinMode(OrangeLED, OUTPUT);
  pinMode(RedLED, OUTPUT);

  digitalWrite(GreenLED, LOW);
  digitalWrite(OrangeLED, LOW);
  digitalWrite(RedLED, LOW);

  Serial.println("Setup finished");
}

void loop() {
  Alarm.delay(0); // This delay should be used instead of the normal Arduino delay(), 
                  // for timely processing of alarms and timers. You can pass 0 for minimal delay.
                  
  RF_Listen (); 
}

void RF_Listen (){
  uint8_t buf[VW_MAX_MESSAGE_LEN];
  uint8_t buflen = VW_MAX_MESSAGE_LEN;

  if (vw_get_message(buf, &buflen)) {
    int a;
    for (a = 0; a < buflen; a++) {
      StringReceived[a] = char(buf[a]);
    }

    sscanf(StringReceived, "%d", &distance);
    MySQL_UpdateDistance();
    Serial.print("Distance:  ");
    Serial.println(distance);
  }
  memset( StringReceived, 0, sizeof( StringReceived));
}

void UpdateTrafficLData() {
  DateTime now = rtc.now();
  if (i == 1) {
    UnixTime_green_1 = now.unixtime() + interval + 1;
    UnixTime_red_1 = now.unixtime() + 2 * interval + 1;

    UnixTime_green_2 = now.unixtime() + 3 * interval + 1;
    UnixTime_red_2 = now.unixtime() + 4 * interval + 1;

    MySQL_UpdateTrafficLData();

    i = 0;
  }

  else if (i == 0) {
    UnixTime_red_1 = now.unixtime() + interval + 1;
    UnixTime_green_1 = now.unixtime() + (2 * interval) + 1;

    UnixTime_red_2 = now.unixtime()+ 3 * interval + 1;
    UnixTime_green_2 = now.unixtime() + 4 * interval + 1;

    MySQL_UpdateTrafficLData();

    i = 1;
  }

  Serial.print(" Green_1 at ");
  Serial.print(UnixTime_green_1);
  Serial.print("   Red_1 at ");
  Serial.print(UnixTime_red_1);
  Serial.print("   Green_2 at ");
  Serial.print(UnixTime_green_2);
  Serial.print("   Red_2 at ");
  Serial.println(UnixTime_red_2);
}

// Update traffic light data in MySQL database via PHP-script (SD Card)
void MySQL_UpdateTrafficLData() {
  long dataArray[4]={UnixTime_green_1, UnixTime_red_1, UnixTime_green_2,UnixTime_red_2};
  Process p;
  p.begin("/mnt/sda1/MySQL_UpdateTrafficLData.php");
  for (int b = 0; b < 4; b++){
   p.addParameter(String(dataArray[b]));
   }
  p.run();

  // Read feedback (for debugging)
  while (p.available() > 0) {
    char c = p.read();
    Serial.print(c);
  }
  // Ensure the last bit of data is sent.
  Serial.flush();
}

void MySQL_UpdateDistance(){
  Process p;
  p.begin("/mnt/sda1/MySQL_UpdateDistance.php");
  p.addParameter(String(distance));
  p.run();

  // Read feedback (for debugging)
  while (p.available() > 0) {
    char c = p.read();
    Serial.print(c);
  }
  // Ensure the last bit of data is sent.
  Serial.flush();
}

void PrintCurrentTime() {
  DateTime now = rtc.now();
  SetLEDsTrafficL();
  Serial.print(now.hour(), DEC);
  Serial.print(':');
  Serial.print(now.minute(), DEC);
  Serial.print(':');
  Serial.print(now.second(), DEC);
  Serial.print("    ");
  Serial.println(now.unixtime());
}

void SetLEDsTrafficL () {
  DateTime now = rtc.now();
  s_till_orange = UnixTime_red_1 - now.unixtime();
  
  if (i == 0) {
    digitalWrite(GreenLED, LOW);
    digitalWrite(OrangeLED, LOW);
    digitalWrite(RedLED, HIGH);
  }

  if (i == 1 && s_till_orange <= 3) {
    digitalWrite(GreenLED, LOW);
    digitalWrite(OrangeLED, HIGH);
    digitalWrite(RedLED, LOW);
  }

  if (i == 1 && s_till_orange > 3) {
    digitalWrite(GreenLED, HIGH);
    digitalWrite(OrangeLED, LOW);
    digitalWrite(RedLED, LOW);
  }
}

MySQL_UpdateTrafficLData.php

PHP
#!/usr/bin/php-cli

<?php
$UnixTime_green_1 = $argv[1];
$UnixTime_red_1 = $argv[2]; 
$UnixTime_green_2 = $argv[3];
$UnixTime_red_2 = $argv[4]; 
$DBServer = 'yourServerName'; 
$DBUser   = 'yourUserName';
$DBPass   = 'yourPassword';
$DBName   = 'yourDBName';  
$conn = new mysqli($DBServer, $DBUser, $DBPass, $DBName);
// check connection
if ($conn->connect_error) {
  trigger_error('Database connection failed: '  . $conn->connect_error, E_USER_ERROR);
}
$sql="UPDATE TrafficL_data SET UnixTime_green_1='$UnixTime_green_1', UnixTime_red_1='$UnixTime_red_1',UnixTime_green_2='$UnixTime_green_2', UnixTime_red_2='$UnixTime_red_2' WHERE id=1";
if($conn->query($sql) === false) {
  trigger_error('Wrong SQL: ' . $sql . ' Error: ' . $conn->error, E_USER_ERROR);
}
else{
echo "Data inserted!\n";
} 
?>

MySQL_UpdateDistance.php

PHP
#!/usr/bin/php-cli
<?php
$Distance = $argv[1];
$DBServer = 'yourServerName';
$DBUser   = 'yourUserName';
$DBPass   = 'yourPassword';
$DBName   = 'yourDBName';
$conn = new mysqli($DBServer, $DBUser, $DBPass, $DBName);
// check connection
if ($conn->connect_error) {
  trigger_error('Database connection failed: '  . $conn->connect_error, E_USER_ERROR);
}
$sql="UPDATE TrafficL_data SET Distance='$Distance'WHERE id=1";

if($conn->query($sql) === false) {
  trigger_error('Wrong SQL: ' . $sql . ' Error: ' . $conn->error, E_USER_ERROR);
}
else{
echo "Distance inserted!\n";
}
?>

EchoJSON

PHP
<?php
define('HOST','yourServerName');
define('USER','yourUserName');
define('PASS','yourPassword');
define('DB','yourDBName');
 
$con = mysqli_connect(HOST,USER,PASS,DB);
 
$sql = "select * from TrafficL_data";
 
$res = mysqli_query($con,$sql);
 
while($row = mysqli_fetch_array($res,MYSQLI_BOTH)){
printf('[
    {
        "TrafficLArray":[
                {
                "UnixTime_green_1":"%s",
                "UnixTime_red_1":"%s",
                "UnixTime_green_2":"%s",
                "UnixTime_red_2":"%s",
                "Distance":"%s"
            }
        ]
    }
]', $row['UnixTime_green_1'], $row['UnixTime_red_1'],$row['UnixTime_green_2'],$row['UnixTime_red_2'],$row['Distance']);
}
 
 
mysqli_close($con);
 
?>

MainActivity.java

Java
package com.example.xxx.xxx;// change xxx xxx


import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

import android.util.Log;
import android.widget.TextView;

import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.JsonArrayRequest;
import com.android.volley.toolbox.Volley;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

//import java.text.DateFormat;
import java.util.Date;
import java.util.Timer;
//import java.util.TimerTask;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;


public class MainActivity extends AppCompatActivity {
    // Will show the string "data" that holds the results
    TextView results;
    //The textview that holds the recommended speed
    TextView recSpeed;

    // URL of object to be parsed
    String JsonURL = "YourURLhere";

    // This string will hold the results
    String data = "";
    // Defining the Volley request queue that handles the URL request concurrently
    RequestQueue requestQueue;

    //timer object to uppdate the data every second
    //Timer timer;

    //The speedLimit (cm/s)
    private final static double maxSpeed = 18;
    //The recommended speed
    private double speed;

    //number of times in the table
    public final static int NUMBER_OF_ENTRIES = 2;
    //array with the times when it is green
    long[] unixTimesGreen = new long[NUMBER_OF_ENTRIES];
    //array with the times when it is red
    long[] unixTimesRed = new long[NUMBER_OF_ENTRIES];
    //variable which hold the distance
    private double distance;

    //variables for repeating updateTable
    private final ScheduledExecutorService scheduler = Executors.newSingleThreadScheduledExecutor();

    //for testing:
    private Future<?> timingTask;

    public void tick(long milliseconds) {
        timingTask = scheduler.scheduleAtFixedRate(new Runnable() {
            public void run() {
                updateTable();
            }
        }, 0, milliseconds, TimeUnit.MILLISECONDS);
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //textViews to cast results to
        results = (TextView) findViewById(R.id.jsonData);

        recSpeed = (TextView) findViewById(R.id.recommendedSpeed);

        //initialize table
        updateTable();

        //update app every 100 milliseconds
        tick(500);

        //for working with a timer object to repeatedly update
        /**
        timer = new Timer("Timer");
        timer.schedule(new UpdateTable(),(long)100,(long)100);
         */

    }

    //for working with timer object to repeatedly update
    /**
    private class UpdateTable extends TimerTask{
        public void run(){
            updateTable();
        }
    }
     */

    private void updateTable(){
        //reset String
        data = "";
        // Creates the Volley request queue
        requestQueue = Volley.newRequestQueue(this);

        //for testing
        /**
        // Casts results into the TextView found within the main layout XML with id jsonData
        results = (TextView) findViewById(R.id.jsonData);
         */


        // Creating the JsonArrayRequest class called arrayreq, passing the required parameters
        //JsonURL is the URL to be fetched from
        JsonArrayRequest arrayreq = new JsonArrayRequest(JsonURL,
                // The second parameter Listener overrides the method onResponse() and passes
                //JSONArray as a parameter
                new Response.Listener<JSONArray>() {


                    // Takes the response from the JSON request
                    @Override
                    public void onResponse(JSONArray response) {
                        try {
                            // Retrieves first JSON object in outer array
                            JSONObject TrafficLObj = response.getJSONObject(0);
                            // Retrieves "trafficArry" from the JSON object
                            JSONArray trafficArry = TrafficLObj.getJSONArray("TrafficLArray");
                            // Iterates through the JSON Array getting objects and adding them
                            //to the list view until there are no more objects in trafficArry
                            for (int i = 0; i < trafficArry.length(); i++) {
                                //gets each JSON object within the JSON array
                                JSONObject jsonObject = trafficArry.getJSONObject(i);

                                //arrays for storing the Strings
                                String[] green = new String[NUMBER_OF_ENTRIES];
                                String[] red = new String[NUMBER_OF_ENTRIES];

                                //String for distance
                                String distanceTemp = jsonObject.getString("Distance");

                                distance = (double)Long.parseLong(distanceTemp);

                                // Retrieves the string
                                // and converts them into javascript objects
                                green[0] = jsonObject.getString("UnixTime_green_1");
                                red[0] = jsonObject.getString("UnixTime_red_1");
                                green[1] = jsonObject.getString("UnixTime_green_2");
                                red[1] = jsonObject.getString("UnixTime_red_2");

                                // Converts Strings retrieved from JSon object to longs
                               for (int j = 0; j < unixTimesRed.length; j++){
                                   unixTimesGreen[j] = Long.parseLong(green[j]);
                                   unixTimesRed[j] = Long.parseLong(red[j]);
                               }

                                //for testing
                                /**
                                //create Date Objects to print out readable dates
                                Date green_1 = new Date(IntUnixTime_green*1000);
                                Date green_2 = new Date(IntUnixTime_green_2*1000);
                                Date red_1 = new Date(IntUnixTime_red*1000);
                                Date red_2 = new Date(IntUnixTime_red_2*1000);


                                /**
                                // Adds strings from the current object to the data string
                                //spacing is included at the end to separate the results from
                                //one another
                                data += "\nID " + (i + 1) +
                                        "\nUnixTime green:  " + green_1.toString() +
                                        "\nUnixTime red:  " + red_1.toString() +
                                        "\nUnixTime green_2:  " + green_2.toString() +
                                        "\nUnixTime red_2:  " + red_2.toString()
                                        +
                                        "\nSum = " + (new Date(currentTime)).toString();
                                 */
                            }//end for

                            // Adds the data string to the TextView "results"
                            //for testing
                            /**
                            results.setText(data);
                             */

                            updateTextView();

                        }//end try

                        // Try and catch are included to handle any errors due to JSON
                        catch (JSONException e) {
                            // If an error occurs, this prints the error to the log
                            e.printStackTrace();
                        }//end catch
                    }//end onResponse
                    //end response.listener
                },
                // The final parameter overrides the method onErrorResponse() and passes VolleyError
                //as a parameter
                new Response.ErrorListener() {
                    @Override
                    // Handles errors that occur due to Volley
                    public void onErrorResponse(VolleyError error) {
                        Log.e("Volley", "Error");
                    }
                }
        );
        // Adds the JSON array request "arrayreq" to the request queue
        requestQueue.add(arrayreq);
    }//end updateTable

    private void updateTextView(){
        //update time info
        StringBuilder builder = new StringBuilder("");

        for (int i = 0; i < unixTimesGreen.length; i++){
            builder.append("unixTimeGreen");
            builder.append(i);
            builder.append(": ");
            builder.append((new Date(unixTimesGreen[i]*1000)).toString());
            builder.append("\n");

            builder.append("unixTimeRed");
            builder.append(i);
            builder.append(": ");
            builder.append((new Date(unixTimesRed[i]*1000)).toString());
            builder.append("\n");
        }
        builder.append("distance: " + distance);

        //results.setText(builder.toString());

        //update speed
        speedCalc();
        String s = String.format("%.0f",speed);
        recSpeed.setText(s);
    }

    private void speedCalc(){

        int interval = 0;
        double time = (double)System.currentTimeMillis()/1000;
        double diff;

       for (int i = 0; i < NUMBER_OF_ENTRIES; i++){
           diff = unixTimesRed[interval] - time;
           speed = distance/((diff)/1000);
           interval++;
       }

        interval = interval-1;
        if(distance/((unixTimesGreen[interval]-time)) > maxSpeed)
            speed = maxSpeed;
        else
            speed = distance/((unixTimesGreen[interval]-time));

        speed = speed*5;
    }
}

AndroidManifest.xml

XML
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.xxx.xxx">// change xxx xxx

    <uses-permission android:name="android.permission.INTERNET"/>

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

strings.xml

XML
"NooitRood", meaning: "NeverRed"
<resources>
    <string name="app_name">NooitRood</string>
</resources>

activity_main.xml

XML
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginLeft="16dp"
    android:layout_marginRight="16dp"
    tools:context="com.example.xxx.xxx.MainActivity"// change xxx xxx
    android:orientation="vertical">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:paddingBottom="10dp"
        android:textAppearance="?android:attr/textAppearanceSmall"
        android:text="Aanbevolen snelheid:"
        android:textSize="20sp"
        android:textStyle="bold"
        android:id="@+id/jsonData"
        android:textColor="#000000" />

    <TextView
        android:layout_width="900px"
        android:layout_height="900px"
        android:layout_gravity="center_horizontal"
        android:paddingTop="10dp"
        android:id="@+id/recommendedSpeed"
        android:textSize="120sp"
        android:textColor="#000000"
        android:textStyle="bold"
        android:gravity="center"
        android:background="@drawable/gebodsbord"/>

</LinearLayout>

Credits

Joppe Smeets

Joppe Smeets

1 project • 10 followers
Pieter Luyten

Pieter Luyten

1 project • 9 followers

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