section3_lecture27_keypad_part5_quiz.ino

/**************************************************
Udemy Arduino Step-by-Step Course
Section 3 Interactive Lecture 27 Keypad Part 5 Quiz
by J. Cantlin 
December 21, 2015
***************************************************/

/**************************************************
Summary of Arduino Analog Pins Used:
A0 = 4x4 Keypad
A1 = LDR Light Dependent Resistor
A2 = 
A3 = 
A4 = 
A5 = 
***************************************************/

/**************************************************
Summary of Arduino Digital Pins Used:
00 = 
01 = 
02 = DHT11 Temperature-Humidity Sensor
03 = 
04 = 
05 = 
06 = 
07 = 1602 LCD Pin 4 RS (Register Select)
08 = 1602 LCD Pin 6 EN (Enable Signal)
09 = 1602 LCD Pin 11 DB4 (Data Bus Line 4)
10 = 1602 LCD Pin 12 DB4 (Data Bus Line 5)
11 = 1602 LCD Pin 13 DB4 (Data Bus Line 6)
13 = 1602 LCD Pin 14 DB4 (Data Bus Line 7)
***************************************************/


/**************************************************
DHT11 Temperature-Humidy Sensor
Uses library DHT.h
Must define DHT sensor type, DHT11,  DHT21, DHT22 also.
Call the library using DHT dht(pin_used,dht_sensor_type).
External Pull Up Resistor:
The DHT11 needs a 5k ohm pullup resistor, connect it
between the 5v power and the signal line. The
Arduino has internal pull-ups which could be used,
but their exact value in unknown. (10k to 40k?) so
use the known 5k external pull up resistor instead.
***************************************************/
#include "DHT.h"
#define DHTPIN 2          //analog pin DHT sensor uses
#define DHTTYPE DHT11     //type of sensor 
DHT dht(DHTPIN, DHTTYPE); //call DHT library
/**************************************************/

/**************************************************
1602 LCD Display - 16 Characters-Two Lines
This sketch is used with an Adafruit P-tec P-1602-17 16x2 LCD.
The LiquidCrystal library works with all LCD displays that are
compatible with the Hitachi HD44780 driver. This is a 
common 16x2 display and uses a 16-pin interface. The
LiquidCrystal Library is modified "Hello World"
from the Arduino Reference Library.
Summary of 1602 Pins Used:
01 = Ground (-)
02 = 5vdc (+) 
03 = Conrast - wiper arm of 10k ohm pot (5vdc)
04 = RS (Register Select)
05 = GROUND (no display unless pin 5 grounded)
06 = EN or E (Enable Signal)
07 = 
08 = 
09 = 
10 = 
11 = DB4 (Data Bus Line 4)
12 = DB5 (Data Bus Line 5)
13 = DB6 (Data Bus Line 6)
14 = DB7 (Data Bus Line 7)
15 = Backlight Power (+ 5vdc)
16 = Backlight Ground (-)
***************************************************/
#include <LiquidCrystal.h>  //LCD library for 16x2 text LCD
LiquidCrystal lcd(7, 8, 9, 10, 11, 12); //define Arduino pins used with LCD
/**************************************************/

//define temperature and humidy ralated variables
float h = 0.0;
float t = 0.0;
float t_degF = 0.0;

//define LDR - light dependent resistor ralated variables
int ldr = 0;

//define keypad related variables
char* keypressed = 0;   //the * is a pointer.
int keyboardPin = 0;    // Analog input pin that the keypad is attached to
int keyboardValue = 0;  // value read from the keyboard

void setup()
{//***start setup function**** 
  dht.begin();         //start dht function.
  lcd.begin(16, 2);   //start LCD with 16 colums 2 rows 
  Serial.begin(9600);  //hardware serial to PC  
  lcd.print("SBS Quiz"); //print initial message to LCD
  delay(100); //initial delay in millisec to read display, let circuit settle.
}//***endof setup function****

void loop()
{//***start infinite loop****

  keyboardValue = analogRead(A0); // read the keyboard value (0 - 1023)

  //do nothing until a key is pressed
  while (keyboardValue < 25)
    {//****start while no key pressed loop****  
    // Reading temperature or humidity takes about 250 milliseconds!
    // Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)
    h = dht.readHumidity();
    t = dht.readTemperature();
    t_degF = 1.8*t+32.0;
    ldr = analogRead(A1);
    keyboardValue = analogRead(A0); 
    delay(50);
    }//****endof while no key pressed loop**** 

  //when a key is pressed get its value                                                        
  readkeyboard(); //get the value of key being pressed "keypressed" i.e. 0-9 
  
}//***endof infinite loop****

void readkeyboard()
{//***start read keyboard function****  
   keyboardValue = analogRead((A0)); // read the value (0-1023)
   Serial.print("Pin value:");           
   Serial.println( keyboardValue);  
   if (keyboardValue <25){keypressed = "n";} //measured 0.0v
   if ((keyboardValue >870) && (keyboardValue < 878))
         {
         keypressed = "1";            //Keypad 1 pressed
         lcd.clear();                 //clear LCD
         lcd.setCursor(0, 0);         //move cursor to start of first row
         lcd.print("Temp. deg F");    //print title on first row
         lcd.setCursor(0, 1);         //move cursor to start of second row.
         lcd.print(t_degF,DEC);       //DEC means base ten decimal 
         delay(200);        
         }
   if ((keyboardValue >763) && (keyboardValue < 771))
         {
         keypressed = "2";            //Keypad 2 pressed
         lcd.clear();                 //clear LCD
         lcd.setCursor(0, 0);         //move cursor to start of first row
         lcd.print("Humidity %");     //print title on first row
         lcd.setCursor(0, 1);         //move cursor to start of second row.
         lcd.print(h,DEC);            //DEC means base ten decimal 
         delay(200);         
         }
   if ((keyboardValue >659) && (keyboardValue < 667))
         {keypressed = "3";           //Keypad 3 pressed
         lcd.clear();                 //clear LCD
         lcd.setCursor(0, 0);         //move cursor to start of first row
         lcd.print("Light Intensity");//print title on first row
         lcd.setCursor(0, 1);         //move cursor to start of second row.
         lcd.print(ldr,DEC);          //DEC means base ten decimal 
         delay(200); 
         }
   //if ((keyboardValue >612) && (keyboardValue < 616)){keypressed = "A";}
   //if ((keyboardValue >534) && (keyboardValue < 538)){keypressed = "4";}
   //if ((keyboardValue >492) && (keyboardValue < 496)){keypressed = "5";}
   //if ((keyboardValue >447) && (keyboardValue < 451)){keypressed = "6";}
   //if ((keyboardValue >421) && (keyboardValue < 425)){keypressed = "B";}
   //if ((keyboardValue >361) && (keyboardValue < 365)){keypressed = "7";}
   if ((keyboardValue >337) && (keyboardValue < 345))
         {
         keypressed = "8";            //Keypad 8 pressed
         lcd.clear();                 //clear LCD
         lcd.setCursor(0, 0);         //move cursor to start of first row
         lcd.print("Hello from");     //print message on first row
         lcd.setCursor(0, 1);         //move cursor to start of second row.
         lcd.print("John Cantlin");   //print message on first row
         delay(200); 
         }
   //if ((keyboardValue >319) && (keyboardValue < 323)){keypressed = "9";}
   //if ((keyboardValue >306) && (keyboardValue < 310)){keypressed = "C";}
   //if ((keyboardValue >279) && (keyboardValue < 283)){keypressed = "*";}
   //if ((keyboardValue >266) && (keyboardValue < 270)){keypressed = "0";}
   //if ((keyboardValue >252) && (keyboardValue < 256)){keypressed = "#";}
   //if ((keyboardValue >245) && (keyboardValue < 249)){keypressed = "D";}
   //if (keyboardValue >950){keypressed = "e";}
     
   while (keyboardValue > 25) 
   {
     delay (100);
     keyboardValue = analogRead((A0)); // read the value (0-1023)
   }//wait until key no longer being pressed before continuing
        
   Serial.println(keypressed);      // print the value back to the Serial view window on your PC
   delay(500);                     // delay milliseconds before the next loop
}//***endof read keyboard function**** 

This quiz coding project is not for credit and is not graded, it is to help other students and the instructor suggested I post the code on Gist. :-)