Laser trip wire coding help

ccartwri · August 17, 2017, 12:59am

Could someone please help me on coding this on two arduino/ genuino 101 boards. There is a picture attached displaying when all the components are

Arduino 1 is the master
Arduino 2 is the slave

Arduino 1 is connected to laser 1 and 2
Arduino 2 is connected to laser 3 and 4

If laser 1 is broken and then laser 2 then the lights trigger.
If laser 4 is broken and then laser 3 then the lights trigger.
If laser 2 is broken and then laser 1 then the lights will not trigger.
If laser 3 is broken and then laser 4 then the lights will not trigger.
If both lasers 1 and 2 or both lasers 3 and 4 are triggered at the same time then the lights trigger- means a heavy flow of traffic, the same if all four lasers are triggered at the same time

Once triggered the light will turn from green to red and flash __ flashes per minute

The idea at the moment is to have ‘people on crossing’ integer which is added to when laser 1 is broken before 2 or laser 4 is broken before 3, and subtracted from when laser 2 is broken before 1 or laser 3 is broken before 4

Existing code:
//Setup for pins that measure the photoresitors attached to lasers.

const int sensorPin_1 = 1;
const int sensorPin_2 = 2;
const int sensorPin_3 = 3;
const int sensorPin_4 = 4;

//Setup for pins to control the colour of the leds
const int ledPinRed = 10;
const int ledPinGreen = 11;

// counter for the number of people on the crossing.
// Must equal zero for the light to be green.
int peopleOnCrossing = 0;

//Levels for Photoresistors - will also need mapping - see other file
int lightLevel_1, high_1 = 200, low_1 = 700;
int lightLevel_2, high_2 = 200, low_2 = 700;
int lightLevel_3, high_3 = 200, low_3 = 700;
int lightLevel_4, high_4 = 200, low_4 = 700;

//Boolean conditions for individual laser triggers
boolean laser1Triggered = false;
boolean laser2Triggered = false;
boolean laser3Triggered = false;
boolean laser4Triggered = false;

//Boolean conditions to determine if somebody has entered the crossing.
boolean enteredFrom1_2 = false;
boolean enteredFrom4_3 = false;

//Boolean conditions to determine if somebody has exited the crossing.
boolean exitFrom1_2 = false;
boolean exitFrom4_3 = false;

void setup() {
// put your setup code here, to run once:

Serial.begin(9600);
pinMode(ledPinRed, OUTPUT);
pinMode(ledPinGreen, OUTPUT);

}

void loop() {

//if the photoresistor gives a value of less than 700, the laser beam has been broken.
//the level of each photoresistor is being given by the lightLevel_1, 2, 3 and 4.

// The following analogRead functions are used to get a value from the photoresistor attached to each laser.

lightLevel_1 = analogRead(sensorPin_1);
lightLevel_2 = analogRead(sensorPin_2);
lightLevel_3 = analogRead(sensorPin_3);
lightLevel_4 = analogRead(sensorPin_4);

Serial.println(“lightLevel_1 =”); //Print the name of laser1 to the serial monitor
Serial.println(lightLevel_1); //Print the value of laser1 to the serial monitor
Serial.println(“lightLevel_2 =”); //Print the name of laser2 to the serial monitor
Serial.println(lightLevel_2); //Print the value of laser2 to the serial monitor
Serial.println(“lightLevel_3 =”); //Print the name of laser3 to the serial monitor
Serial.println(lightLevel_3); //Print the value of laser3 to the serial monitor
Serial.println(“lightLevel_4 =”); //Print the name of laser4 to the serial monitor
Serial.println(lightLevel_4); //Print the value of laser4 to the serial monitor

//check if any lasers have been triggered (write in a function)
if (lightLevel_1<700);
laser1Triggered = true;
if (lightLevel_2<700);
laser2Triggered = true;
if (lightLevel_3<700);
laser3Triggered = true;
if (lightLevel_4<700);
laser4Triggered = true;

// if laser 1 then laser 2 are broken, somebody has entered the left crossing
if(laser1Triggered && !laser2Triggered)
{
enteredFrom1_2 = true;
}
if(laser1Triggered && laser2Triggered && enteredFrom1_2)
{
peopleOnCrossing++;

//reset triggers
laser1Triggered = false;
laser2Triggered = false;
enteredFrom1_2 = false;

}

// if laser 2 and then laser 1 are broken, somebody has exited the left crossing
if(laser2Triggered && !laser1Triggered)
{
exitFrom1_2 = true;
}
if(laser1Triggered && laser2Triggered && exitFrom1_2)
{
peopleOnCrossing–;
//reset triggers
laser1Triggered = false;
laser2Triggered = false;
exitFrom1_2 = false;
}

// if laser 4 then laser 3 are broken, somebody has entered the right crossing
if(laser4Triggered && !laser3Triggered)
{
enteredFrom4_3 = true;
}
if(laser4Triggered && laser3Triggered && enteredFrom4_3)
{
peopleOnCrossing++;
//reset triggers
laser4Triggered = false;
laser3Triggered = false;
enteredFrom4_3 = false;
}

// if laser 3 and then laser 4 are broken, somebody has exited the right crossing
if(laser3Triggered && !laser4Triggered)
{
exitFrom4_3 = true;
}
if(laser3Triggered && laser4Triggered && exitFrom4_3)
{
peopleOnCrossing–;

//Print the status of peopleOnCrossing to the serial monitor
Serial.print (“People on Crossing =”);
Serial.print (peopleOnCrossing);

//reset triggers
laser3Triggered = false;
laser4Triggered = false;
exitFrom4_3= false;

}

// control traffic lights
if(peopleOnCrossing > 0)
{
//change to red light
digitalWrite(ledPinGreen, LOW);
digitalWrite(ledPinRed, HIGH);
Serial.print (“I’m on red”);
}
else
{
//change to green light
digitalWrite (ledPinRed, LOW);
digitalWrite (ledPinGreen, HIGH);
Serial.print (“I’m on Green”);
}
}

quozl · August 17, 2017, 1:50am

Your code lost all the indentation, please use three backticks above and below it to make it readable.

Problem with a counter of people on crossing is that it can be unreliable.

Also, “at the same time” is quite hard to determine.

The Arduino library has a millis() function which tells you the time in milliseconds since reset.

I would code the slave to transmit the state of laser 3 and 4 twice a second.

I would code the master to;

receive messages from the slave, and remember the time, and automatically flash the lights if the time was more than a second ago, a sort of fail to safe mode,
when any of the four laser beams are broken, remember the off time for that photodetector,
when any of the four laser beams are seen, remember the on time for that photodetector,
decide whether to flash the lights based on the remembered times.

For example, on the master;

void loop() {

    /* get the current time */
    now = millis();

    /* receive messages and set last_receive to now */
    ...

    /* detect loss of reception and turn lights on */
    if (now > last_receive + 1000) {
        lights_on();
        last_on = now;
        return;
    }

    /* notice changed to the photodetectors and 
       set beam_{1,2,3,4}_{on,off} */
    ...

    /* if beam 1 and beam 2 are broken, and
       beam 2 was broken after beam 1 */
    if (beam_1_off > beam_1_on &&
        beam_2_off > beam_2_on &&
        beam_2_off > beam_1_off) {

        lights_on();
        last_on = now;
        return;
    }

    if (beam_3_off > beam_3_on &&
        beam_4_off > beam_4_on &&
        beam_4_off > beam_3_off) {

        lights_on();
        last_on = now;
        return;
    }

    /* turn the lights off after N seconds */
    if (now > last_on + 60000) {
        lights_off();
    }
}

You may also have to code something special to handle the 50 day limit for millis(); either reboot or do extra calculations.