Hi All,
I've got a DS1307 RTC module hooked up but I'm confused about something. I uploaded the following code in order to set the date and time. I opened the Serial Monitor to look at the values and I see the clock values. Great. However....if I close the Serial Monitor window, then reopen it, I see that the clock values start over. I thought that once I set the clock it would run contiguously. Even on battery power (if none provided from the Arduino).
What am I doing wrong?
// Maurice Ribble
// 4-17-2008
// http://www.glacialwanderer.com/hobbyrobotics
// This code tests the DS1307 Real Time clock on the Arduino board.
// The ds1307 works in binary coded decimal or BCD. You can look up
// bcd in google if you aren't familior with it. There can output
// a square wave, but I don't expose that in this code. See the
// ds1307 for it's full capabilities.
#include "Wire.h"
#define DS1307_I2C_ADDRESS 0x68
// Convert normal decimal numbers to binary coded decimal
byte decToBcd(byte val)
{
return ( (val/10*16) + (val%10) );
}
// Convert binary coded decimal to normal decimal numbers
byte bcdToDec(byte val)
{
return ( (val/16*10) + (val%16) );
}
// Stops the DS1307, but it has the side effect of setting seconds to 0
// Probably only want to use this for testing
/*void stopDs1307()
{
Wire.beginTransmission(DS1307_I2C_ADDRESS);
Wire.send(0);
Wire.send(0x80);
Wire.endTransmission();
}*/
// 1) Sets the date and time on the ds1307
// 2) Starts the clock
// 3) Sets hour mode to 24 hour clock
// Assumes you're passing in valid numbers
// UNCOMMENT THE FOLLOWING TO SET THE DATE/TIME
/*
void setDateDs1307(byte second, // 0-59
byte minute, // 0-59
byte hour, // 1-23
byte dayOfWeek, // 1-7
byte dayOfMonth, // 1-28/29/30/31
byte month, // 1-12
byte year) // 0-99
{
Wire.beginTransmission(DS1307_I2C_ADDRESS);
Wire.send(0);
Wire.send(decToBcd(second)); // 0 to bit 7 starts the clock
Wire.send(decToBcd(minute));
Wire.send(decToBcd(hour)); // If you want 12 hour am/pm you need to set
// bit 6 (also need to change readDateDs1307)
Wire.send(decToBcd(dayOfWeek));
Wire.send(decToBcd(dayOfMonth));
Wire.send(decToBcd(month));
Wire.send(decToBcd(year));
Wire.endTransmission();
}
*/
// Gets the date and time from the ds1307
void getDateDs1307(byte *second,
byte *minute,
byte *hour,
byte *dayOfWeek,
byte *dayOfMonth,
byte *month,
byte *year)
{
// Reset the register pointer
Wire.beginTransmission(DS1307_I2C_ADDRESS);
Wire.send(0);
Wire.endTransmission();
Wire.requestFrom(DS1307_I2C_ADDRESS, 7);
// A few of these need masks because certain bits are control bits
*second = bcdToDec(Wire.receive() & 0x7f);
*minute = bcdToDec(Wire.receive());
*hour = bcdToDec(Wire.receive() & 0x3f); // Need to change this if 12 hour am/pm
*dayOfWeek = bcdToDec(Wire.receive());
*dayOfMonth = bcdToDec(Wire.receive());
*month = bcdToDec(Wire.receive());
*year = bcdToDec(Wire.receive());
}
void setup()
{
byte second, minute, hour, dayOfWeek, dayOfMonth, month, year;
Wire.begin();
Serial.begin(9600);
// Change these values to what you want to set your clock to.
// You probably only want to set your clock once and then remove
// the setDateDs1307 call.
// UNCOMMENT THE FOLLOWING TO SET THE DATE/TIME
/* second = 0;
minute = 48;
hour = 21;
dayOfWeek = 1;
dayOfMonth = 7;
month = 3;
year = 10;
setDateDs1307(second, minute, hour, dayOfWeek, dayOfMonth, month, year);
*/
}
void loop()
{
byte second, minute, hour, dayOfWeek, dayOfMonth, month, year;
getDateDs1307(&second, &minute, &hour, &dayOfWeek, &dayOfMonth, &month, &year);
Serial.print(hour, DEC);
Serial.print(":");
Serial.print(minute, DEC);
Serial.print(":");
Serial.print(second, DEC);
Serial.print(" ");
Serial.print(month, DEC);
Serial.print("/");
Serial.print(dayOfMonth, DEC);
Serial.print("/");
Serial.print(year, DEC);
Serial.print(" Day_of_week:");
Serial.println(dayOfWeek, DEC);
delay(1000);
}