switch connection
Basic diagram.

Display Time/Date with Arduino, LCD Display, and Ds1307 RTC

This project demonstrates the use of the MCP23016 I/O expander being used with a LCD display and a Ds1307 RTC to display time/date. It combines several other earlier demonstrations. I used the MCP23016 I/O expander due to the lack of output pins on the ATMEGA168/Arduino.

switch connection
Where to connect the MCP23016.




#include <Wire.h>

byte blinkPin = 13;
byte swIn = 2; // square wave or pulse in
byte SW0 = 4;
byte SW1 = 5;
byte SW2 = 6;

volatile byte irq_flag = LOW; // declare IRQ flag

// names can't have number as fist char.
const byte HOME = 0x02;
const byte Line2 = 0x0c;
const byte CL = 0x10; // cursor left
const byte CR = 0x14; // cursor right
const byte SL = 0x18; // Shifts entire display left
const byte SR = 0x1c; // Shifts entire display right 


int j;

void setup()

{
  Wire.begin(); // join i2c bus (address optional for master)
  pinMode(blinkPin, OUTPUT);
  digitalWrite(blinkPin, 0);

  attachInterrupt(0, set_irq_flag0, FALLING);  // interupt 0 pin 2

  pinMode(swIn, INPUT); // pullups on connect to DS1307 Square wave output pin 
  pinMode(SW0, INPUT);  // N.O. push button switch
  pinMode(SW1, INPUT);  // N.O. push button switch
  pinMode(SW2, INPUT);  // N.O. push button switch
  // activate internal pullups:
  digitalWrite(swIn, HIGH);
  digitalWrite(SW0, HIGH);
  digitalWrite(SW1, HIGH);
  digitalWrite(SW2, HIGH);


  Wire.beginTransmission(0x20);  // set mcp23016 output configuration:
  Wire.send(0x06);  // pointer
  Wire.send(0x00);  // DDR Port0 all output
  Wire.send(0x0F);  // DDR 0-3 input 4-7 output
  Wire.endTransmission(); 
  // setup port 1 D7 = E; D6 = RS 
  Wire.beginTransmission(0x20); 
  Wire.send(0x01); //pointer to port 1
  Wire.send(B10000000); // setup for command mode
  Wire.endTransmission(); 

  writeCommand(0x38); // 2 line mode
  writeCommand(0x0F); // blinking cursor
  CLR(); // clear dispaly
  writeCommand(HOME); // optional



}

void loop()
{

  if (irq_flag == HIGH) { 
    displayTime(); // write time/date to display
    irq_flag = 0; // clear IRQ flag.
  }  // end if 

  if (digitalRead(SW0) != HIGH) set_time(); // hold the switch to set time

} // end loop



// output time to display

void displayTime()   {

  Wire.beginTransmission(0x68); // access ds1307 RTC
  Wire.send(0);
  Wire.endTransmission();
  Wire.requestFrom(0x68, 7);
  byte secs = Wire.receive();
  byte mins = Wire.receive();
  byte hrs = Wire.receive();
  byte day = Wire.receive();
  byte date = Wire.receive();
  byte month = Wire.receive();
  byte year = Wire.receive();

  typeln("Time: \n", 1);
  typeBCD(hrs);   
  type(':');
  typeBCD(mins);     
  type(':');
  typeBCD(secs);

  // use MM-DD-YYYY

  typeln("Date: \n", 2);
  typeBCD(month);     
  type('-');
  typeBCD(date);
  type('-');
  type('2');
  type('0');
  typeBCD(year); 
  toggle(blinkPin);
 
}  // end display time



// sets IRQ flag on iterrupt from digital pin 2.

void set_irq_flag0() 
{
  irq_flag = HIGH; // set flag
} 

// set time subroutine 
void set_time()   {
  byte minutes = 0;
  byte hours = 0;
  byte day_of_week = 0x03;
  byte day = 0x17;
  byte month = 0x02;
  byte year = 0x10;


  while (digitalRead(SW1) != 0) // set minutes
  { 
    CLR(); 
    if (digitalRead(SW2) == 0) minutes++;        
    if ((minutes & 0x0f) > 9) minutes = minutes + 6;
    if (minutes > 0x59) minutes = 0;
    typeln("Minutes = \n", 1);
    typeBCD(minutes);
    delay(1000);



  }
  delay(1000);
  while (digitalRead(SW1) != 0) // set hours
  { 
    CLR();
    if (digitalRead(SW2) == 0) hours++;       
    if ((hours & 0x0f) > 9) hours =  hours + 6;
    if (hours > 0x23) hours = 0;
    typeln("Hours = \n", 1);
    typeBCD(hours);
    delay(1000);      


  }

  Wire.beginTransmission(0x68); // activate DS1307
  Wire.send(0); // where to begin
  Wire.send(0x00);          //seconds
  Wire.send(minutes);          //minutes
  Wire.send(0x80 | hours);    //hours (24hr time)
  Wire.send(day_of_week);  // Day 01-07
  Wire.send(day);  // Date 0-31
  Wire.send(month);  // month 0-12
  Wire.send(year);  // Year 00-99
  Wire.send(0x10); // Control 0x10 produces a 1 HZ square wave on pin 7. 
  Wire.endTransmission();

} // end setime()


// Below we pass a pointer to array1[0]. If no '\n' then the limit is 16. (0 - 15)
void typeln(char *array1, int i)   {
  delayMicroseconds(1000);
  if (i == 1) writeCommand(0x80); // begin on 1st line
  if (i == 2) writeCommand(0x80 + 0x40); // begin on 2nd line 
  for (int j = 0; (array1[j] != '\n') && (j < 16); j++) type(array1[j]); 
}




// send command to HD44780 display 
//  E High to Low transition write command or data to HD44780 display
//  RS 0 for command, default 1 for data
//  setup port1 D7 = E; D6 = RS 
void writeCommand(char c)   {

  Wire.beginTransmission(0x20);  //  mcp23016 
  Wire.send(0x00); // begin here
  Wire.send(c);  // command code
  Wire.endTransmission();

  Wire.beginTransmission(0x20);  //  mcp23016 
  Wire.send(0x01); // pointer
  Wire.send(B10000000);  // command mode E high
  Wire.endTransmission();

  Wire.beginTransmission(0x20);  //  mcp23016 
  Wire.send(0x01); // pointer 
  Wire.send(B00000000);  // char mode E low
  Wire.endTransmission();

  delayMicroseconds(100);

  Wire.beginTransmission(0x20);  //  mcp23016 
  Wire.send(0x01); //  pointer
  Wire.send(B10000000);  // E high back to command mode
  Wire.endTransmission();


} 

//  send char to HD44780 display 
//  E High to Low transition write command or data to HD44780 display
//  RS 0 for command, default 1 for data
//  setup port1 D7 = E; D6 = RS 

void type(char c)   {

  Wire.beginTransmission(0x20);  //  mcp23016 
  Wire.send(0x00); // begin here
  Wire.send(c);  // data
  Wire.endTransmission();

  Wire.beginTransmission(0x20);  //  mcp23016 
  Wire.send(0x01); // pointer
  Wire.send(B11000000);  // char mode E high
  Wire.endTransmission();

  Wire.beginTransmission(0x20);  //  mcp23016 
  Wire.send(0x01); // pointer 
  Wire.send(B01000000);  // char mode E low
  Wire.endTransmission();

  delayMicroseconds(100);

  Wire.beginTransmission(0x20);  //  mcp23016 
  Wire.send(0x01); //  pointer
  Wire.send(B10000000);  // E high back to command mode
  Wire.endTransmission();


} 


// clear display
void  CLR()   {
  writeCommand(0x01); // clear
}

// this routine types a Hex values to HD44780 display 
// the value from be in BCD form
void typeBCD(byte val)   {

  byte n = val;
  n = (n >> 4) + 48;
  type(n);
  val = (val & B00001111) + 48;
  type(val);

}


// bascspace on display

void BS()   {
  writeCommand(CL);
}



// toggle the state on a pin
void toggle(int pinNum) 
{  
  int pinState = digitalRead(pinNum);
  pinState = !pinState;
  digitalWrite(pinNum, pinState); 
}

switch connection
Bare Bones Kit from Modern Device Company.
This is an example of what is out there, most do the same thing.
This doesn't include the DS1307, switches, etc.

atmega168/arduino in connections

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For more technical details on this see ATMEGA168 Arduino Micro Controller Projects

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