Reaction Timer

Contributors: Nate

Firmware

The code that runs the reaction timer is very straight forward. We simply illuminate a light and wait for the user to press the button. Download and install the example sketch.

A timer counts how many milliseconds it requires for the (slow, slow) human to respond. And, because we don't want the human to cheat, we pick a random amount of time before we turn on the light.

language:c
/*
 Reaction Timer for the World of Wonder Childrens museum in Lafayette, CO
 By: Nathan Seidle (SparkFun Electronics)
 Date: May 6th, 2013
 This code is public domain but you buy me a beer if you use this and we meet someday (Beerware license).

 How to play:
 The button will be pulsing with light. Pressing the button will cause the light to turn off and the game will begin.
 After a few seconds of darkness, the light will light up and the user must press the button as fast as they can.
 Their reaction time is displayed on a 7 segment display.

 If the user presses the button before it is illuminated the display will show '-Err' to indicate error.

 */

#include <SoftwareSerial.h>
SoftwareSerial segmentDisplay(3, 2); //RX, TX to the OpenSegment display

int LED = 9;
int button = 7;

long timeDiff; //Global variable keeps track of your score
int idleLoops = 0;

String gameTime; //Contains the last game time
int gamesPlayed; //Contains the total number of games played for the life of the device

//These functions allow the LED to be really bright when on, and
//just barely on when the game is in idle mode
#define LEDON() analogWrite(LED, 255)
#define LEDLOW() analogWrite(LED, 10)
#define LEDOFF() analogWrite(LED, 0)

void setup()
{
    Serial.begin(115200);

    pinMode(LED, OUTPUT);
    LEDOFF(); //Turn off LED

    pinMode(button, INPUT_PULLUP);

    randomSeed(analogRead(A1)); //Get noise to seed the random number generator

    segmentDisplay.begin(9600); //Talk to the Serial7Segment at 9600 bps
    segmentDisplay.write('v'); //Reset the display - this forces the cursor to return to the beginning of the display

    scrollTitle();
}

void loop()
{
    if(digitalRead(button) == LOW)
    {
        Serial.println("Playing");
        playGame();
        idleLoops = 0;
    }

    pulseTheButton(); //If no one is playing, pulse LED to intice them. Function takes 6 seconds to complete.

    idleLoops++;
    if(idleLoops > 9) //Play a screen saver every 60 seconds.
    {
        scrollTitle(); //Screen saver = display title
        idleLoops = 0;
    }
}

void playGame()
{
    segmentDisplay.write('v'); //Reset the display

    delay(25); //Debounce the button a bit

    while(digitalRead(button) == LOW) ; //Wait for user to stop hitting button

    LEDLOW(); //Turn LED on low to indicate the beginning of the game

    //Get random number of milliseconds
    long lightTime = random(2000, 3500); //From 2 to 3.5 seconds

    long zeroTime = millis();

    while(millis() - zeroTime < lightTime) //Wait for random amount of time to go by
    {
        //If the user hits the button in this time then error out (cheater!)
        if(digitalRead(button) == LOW)
        {
            segmentDisplay.write('v'); //Reset the display
            segmentDisplay.print("-Err");
            Serial.println("Err!");
            blinkButton();
            return;
        }
    }

    //Begin game
    Serial.println("Go!");
    LEDON();
    long beginTime = millis(); //Record this as the beginning of the test

    //Wait for user to hit the button
    while(digitalRead(button) == HIGH)
    {
        //Check to see if the user fails to respond in 10 seconds
        timeDiff = millis() - beginTime;
        if(timeDiff > 9999)
        {
            timeDiff = 9999;
            segmentDisplay.write('v'); //Reset the display
            segmentDisplay.print(timeDiff);
            blinkButton();
            return;
        }
    }

    gameTime = String(timeDiff);

    //Right adjust the time
    if(timeDiff < 10)
        gameTime = "   " + gameTime;
    else if(timeDiff < 100)
        gameTime = "  " + gameTime;
    else if(timeDiff < 1000)
        gameTime = " " + gameTime;

    segmentDisplay.write('v'); //Reset the display
    segmentDisplay.print(gameTime); //Display the game time

    Serial.print("Reaction time:");
    Serial.println(gameTime);

    blinkButton(); //Blink the LED to indicate the end of the game

    //Record that we have played this game
    gamesPlayed++;
    Serial.print("This time played:");
    Serial.println(gamesPlayed);

    //After the game is complete, the display will show the gameTime for awhile
}

//If there is no game going on, pulse the LED on/off
//If the user ever presses the button then return immediately
//This function takes approximately 6 seconds to complete
void pulseTheButton(void)
{
    //Fade LED on
    for(int fadeValue = 0 ; fadeValue <= 255; fadeValue += 5)
    {
        if(digitalRead(button) == LOW) return;

        analogWrite(LED, fadeValue);
        delay(30);
    }

    //Fade LED off
    for(int fadeValue = 255 ; fadeValue >= 0; fadeValue -= 5)
    {
        if(digitalRead(button) == LOW) return;

        analogWrite(LED, fadeValue);
        delay(30);
    }

    //Turn LED off for awhile
    for(int x = 0 ; x < 100 ; x++)
    {
        if(digitalRead(button) == LOW) return;

        analogWrite(LED, 0);
        delay(30);
    }
}

//Quickly blinks to button indicating the end of a game
void blinkButton()
{
    for(int x = 0 ; x < 7 ; x++)
    {
        LEDON();
        delay(60);
        LEDOFF();
        delay(60);
    }
}

//Quickly scrolls the title across the display
void scrollTitle()
{
    String titleStr = String("    reaction speed    ");

    for(int x = 0 ; x < titleStr.length() - 4 ; x++)
    {
        String tempStr = titleStr.substring(x, x + 4); //Chop out four letters from the string

        segmentDisplay.write('v'); //Reset the display
        segmentDisplay.print(tempStr); //Display this substring

        for(int y = 0 ; y < 25 ; y++)
        {
            if(digitalRead(button) == LOW) return; //If the button is pressed, bail!
            delay(10);
        }
    }

    segmentDisplay.write('v'); //Reset the display
    segmentDisplay.print(gameTime); //Display the last game time
}

Load this code onto the RedBoard, and open the terminal at 115200bps. You should see a series of debug statements such as 'Games Played' and 'Err!'.