Satbeginner:
Meanwhile I did some 'googleling' and found this page:Determination of the day of the week - Wikipedia
where they have a real lot information on the DayOfWeek topic.
From there I got this bit of (very compact!) code that does work too
Hmm, sounds like that should've been step one
jurs:
The code posted in #13 calculates wrong results in several cases.Give it a try with this test code:
void setup()
{
Serial.begin(9600);
Serial.println(calcDayOfWeek(1999,12,31));
Serial.println(calcDayOfWeek(2000,1,1));
}
DayOfWeek is surely never 7, it has to be in the range 0 to 6 only!
I think I intentionally used 1 to 7 for that.
Hello
Here is my tiny code with very few 8-bits calculations.
It works fine with RTCs (no century handling)
uint8_t calcDayOfWeek(uint8_t y, uint8_t m, uint8_t d) {
uint8_t dow = y + (y >> 2) + d;
switch (m) {
case 2 :
case 3 :
case 11 : dow++; break;
case 6 : dow += 2; break;
case 9 :
case 12 : dow += 3; break;
case 4 :
case 7 : dow += 4; break;
case 1 :
case 10 : dow += 5; break;
case 5 : dow += 6;
}
if (m > 2 || (y & 3)) dow++;
return dow % 7;
}