I have been wondering if a computer program or sketch exists to make syncing an I2C RTC with the computer system time easy and precise? At the moment I either use
RTC.adjust(DateTime(__DATE__, __TIME__)
which is great but always out by the time it takes to compile etc.... or trying to set the time to account for these delays which is a bit hit and miss - but obviously not ideal.
I'm guessing that this nut has already been cracked so wondering if anyone can point me in the right direction - the RTC I am using is the great DS3231 but suspect code for other I2C RTCs wouldn't be too bad to recycle?
Here is the method I use to set my RTC, it's primitive for sure but simple and effective. I update the fixed values in the setup function for a time ahead maybe 3 mins. Then I upload the sketch to the board. Note that it waits for any character to be sent from the serial monitor before actually preceeding to set the RTC. Then I call up one of the many time reference web sites that have a running time clock being displayed. So when the web site time matches the time I preset into the sketch I hit a character on the serial monitor and the time gets updated in the RTC and the main loop just keeps printing the time data after that. So nothing fancy but I like being "part of the loop".
Lefty
Note that this was written using IDE ver22 and might need tweaking for IDE 1.x ?
/*Reads the value from a Real Time Clock (RTC) DS1307 and displays it in the serial monitor
*
*Created by D. Sjunnesson 1scale1.com d.sjunnesson (at) 1scale1.com
*
*Created with combined information from
*http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1180908809
*http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1191209057
*
*
*Big credit to mattt (please contact me for a more correct name...) from the Arduino forum
*which has written the main part of the library which I have modified
*
*/
#include <WProgram.h>
#include <Wire.h>
#include <DS1307.h> // written by mattt on the Arduino forum and modified by D. Sjunnesson
void setup()
{
Serial.begin(57600);
Serial.println ("Hit a key to start"); // signal initalization done
while(Serial.available() == 0){}
// Hit upload about 10 seconds before selected time
RTC.stop();
RTC.set(DS1307_SEC,0); //set the seconds
RTC.set(DS1307_MIN,28); //set the minutes
RTC.set(DS1307_HR,23); //set the hours note 24 hour clock
RTC.set(DS1307_DOW,5); //set the day of the week
RTC.set(DS1307_DATE,13); //set the date
RTC.set(DS1307_MTH,1); //set the month
RTC.set(DS1307_YR,11); //set the year
RTC.start();
}
void loop()
{
Serial.print(RTC.get(DS1307_HR,true)); //read the hour and also update all the values by pushing in true
Serial.print(":");
Serial.print(RTC.get(DS1307_MIN,false));//read minutes without update (false)
Serial.print(":");
Serial.print(RTC.get(DS1307_SEC,false));//read seconds
Serial.print(" "); // some space for a more happy life
Serial.print(RTC.get(DS1307_DATE,false));//read date
Serial.print("/");
Serial.print(RTC.get(DS1307_MTH,false));//read month
Serial.print("/");
Serial.print(RTC.get(DS1307_YR,false)); //read year
Serial.println();
delay(1000);
}
The Compile Time Error seems to be close to consistant for any particular PC so why could one not adjust the delayed time then add a correction factor - something like seconds = seconds + xxx then see how that goes? Don't know enought to write the code myself which may be obvious from my suggestion above.
Hi, Yes - thanks for the input I have since found an example of some nice code to do this via the serial window - I wasn't sure if I could post it here to start with but have since found it in the public domain so I guess its OK.
It is written for the DS3231 RTC but could be adapted for the DS1307 - the trick is that it is written for WaspMote which is Arduino-esq but needs a bit of translating as they have their own bespoke functions like USB.print which is Serial.print - I made a start but soon ran out of ability.... take a look here if you are interested - you basically use the serial window to predefine a time and date which is stored until a set command is sent to serial which sets the time specified in an instant.... so pretty accurate.
I have since found an example of some nice code to do this via the serial window - I wasn't sure if I could post it here to start with but have since found it in the public domain so I guess its OK.