MarkS1964:
So my question is,
in peoples opinion is it more efficient to query the Registers or employ another Library (Wire.h).
Here's how I do it:
#include <Wire.h>
byte ss=0, mi=0, hh=0, wd=6, dd=1, mo=1, yy=0;
void setup()
{
Wire.begin();
Serial.begin(9600);
// clear /EOSC bit
// Sometimes necessary to ensure that the clock
// keeps running on just battery power. Once set,
// it shouldn't need to be reset but it's a good
// idea to make sure.
// Wire.beginTransmission(0x68); // address DS3231
// Wire.write(0x0E); // select register
// Wire.write(0b00011100); // write register bitmap, bit 7 is /EOSC
// Wire.endTransmission();
}
void loop()
{
// ask RTC for the time
// send request to receive data starting at register 0
Wire.beginTransmission(0x68); // 0x68 is DS3231 device address
Wire.write((byte)0); // start at register 0
Wire.endTransmission();
Wire.requestFrom(0x68, 7); // request seven bytes (ss, mi, hh, wd, dd, mo, yy)
// check for a reply from the RTC, and use it if we can
if (Wire.available() >= 7) {
// if we're here, we got a reply and it is long enough
// so now we read the time
ss = bcd2bin(Wire.read()); // get seconds
mi = bcd2bin(Wire.read()); // get minutes
hh = bcd2bin(Wire.read()); // get hours
wd = bcd2bin(Wire.read());
dd = bcd2bin(Wire.read());
mo = bcd2bin(Wire.read());
yy = bcd2bin(Wire.read());
// show that we successfully got the time
Serial.print("Got the time: ");
printTime();
}
else {
// if we're here, that means we were unable to read the time
Serial.println("Unable to read time from RTC");
}
delay(500);
}
byte bcd2bin(byte x) {
// converts from binary-coded decimal to a "regular" binary number
return ((((x >> 4) & 0xF) * 10) + (x & 0xF)) ;
}
void printTime() {
// just like it says on the tin
Serial.print ("\'");
if (yy<10) Serial.print("0"); Serial.print(yy,DEC); Serial.print("-");
if (mo<10) Serial.print("0"); Serial.print(mo,DEC); Serial.print("-");
if (dd<10) Serial.print("0"); Serial.print(dd,DEC); Serial.print("(");
switch (wd) {
case 1: Serial.print("Mon"); break;
case 2: Serial.print("Tue"); break;
case 3: Serial.print("Wed"); break;
case 4: Serial.print("Thu"); break;
case 5: Serial.print("Fri"); break;
case 6: Serial.print("Sat"); break;
case 7: Serial.print("Sun"); break;
default: Serial.print("Bad");
}
Serial.print(") ");
if (hh<10) Serial.print("0"); Serial.print(hh,DEC); Serial.print(":");
if (mi<10) Serial.print("0"); Serial.print(mi,DEC); Serial.print(":");
if (ss<10) Serial.print("0"); Serial.print(ss,DEC); Serial.println("");
}
This should print the date and time to the serial monitor. Remember to select the correct baud rate.
Note that I number the weekdays starting from 1 for Monday. Some people prefer to use 1 for Sunday.