// // 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 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. second = 45; minute = 3; hour = 7; dayOfWeek = 5; dayOfMonth = 17; month = 4; year = 8; 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); }