[SOLVED] How to know the last day of the month in DS1307 RTCC ?

[ADGAN]

Hi! I'm using a DS1307 as a RTCC for my design. I need to know the last date of the month & need to display it on the LCD. Does anybody know how to do it in a direct or a indirect method ?

Note:
I'm using MikroC pro & PIC18F45k22

 

[BradtheRad]

There are software routines that take a given year/month/day, and convert to Julian days. (Astronomers use Julian days to track time.)

If you know what day falls on Jan. 1, then you divide the difference by 7 (or use MODULO command), and the remainder tells you how many days you should add to the day on Jan. 1. And you arrive at your answer.

 

[ADGAN]

Thanks for the reply. Can you elaborate your answer and please note that I made a mistake in the previous post. I need the date not the day.

 

[jayanth.devarayanadurga]

Date register address 0x04


Range 01 - 31

BIT7 BIT6 BIT5 BIT4 BIT3 BIT2 BIT1 BIT0


Bits0 to Bits3 = units place
Bits 4 and 5 are tens place
Bits 6 and 7 are always 0


for date 31 you need BD 31

BCD 31 =

0011 0001

You write

11 to bits 4 and 5 and 0001 to bits 0 to 3.

 

[ADGAN]

Thanks for the reply. But I want to display the last date of the previous month on the LCD throughout the current month. The problem is some months have 28, 29, 30 or 31 days

 

[jayanth.devarayanadurga]

algo

if month = jan, mar, may, july, aug, oct, dec then

	if date = 31?

		memdata = date

else if month = feb, apr, jun, sep, nov then

	if month = feb then

		if year = leap then

			if date = 28 then

				memdate = date

		else if year not leap

			if date = 29 then
		
				memdate = date


	else if month != feb then

		if date = 30 then

			memdate = date

 

[ADGAN]

Thank you !