Whats the timing to write in the rtc????

Hello seniors.. I have succesfully configure my ds12c887 rtc to be read and to display everything on the jhd162a 16*2 lcd using 16f877a...

Problem.. When i m tryng to update the date and time its getting hard to do that..

Last time i tried to turn on the swuarewave pulse for 2hz but it ws not working...but then i repeated the call for that sub for once again and it worked..

I want to know that after setting the set bit in registerb do i need to wait for sm time to send the data to the rtc to be changed????
Or do i need to monitor the uip bit in the register a for a particular behaviour after which i can send the data to the rtc???

What shud be the procedure to change data in the rtc???
Thanx in advance...

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Moreover there is one more problem, I have set the rtc to work on 24hrs mode, and now what happened is that after 24:59:59 it should have come to 01.00.01 but it got incremented to 25.00.01, and right now its on the 26 at hour place,.. What going inside my RTC?? Any suggestion plz????

Thanks in advance

Zip and post your project files. Mention which Compiler and what Clock frequency are you using.

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I found this but it is for 8051.

brother i m not using the prot for the simulation, i hav the cck on the breadboard, i m using mpasm compiler, and pic is working on 20mhz i hav written all the code in the assembly...
plz let me chk the code you've uploaded.. i just need to know that wen we need to update the data on the rtc, what precautions we hav to follow..

here is the code that i wrote for the rtc.. its in assembly

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i hav seen many circuits online and hav noticed one thing that most of them are using the 12mhz crystal and wen connect 33pf capacitors on that crystan the freq get more reduced.. and the circuit i m using is having the 20mhz crystal, i think the main problem is in the timing routines.. i think i need to do the homework on the timing routines and i ll get my problem fixed..

m i on the write way????

hello, today again i tried ne thing, i used my TURNOFFRTC command to turn off the rtc and stop the counter, as the pic got programmed with the code, i got needed to reset the pic for several times to get the rtc turned off... is that really a timing problem???

Sorry, I can't help much with asm code. I can help with C code.

ok, thanx for your reply, c has almost no error because everything is readymade, i just need to clear the fact that this is a timing issue or waht, or i hav use the oscilloscope for exact timing routines..

Post your circuit. Is it an I2C RTC or SPI RTC ? Zip and post your latest project.

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You can use this tool to create proper delays based on your PIC clock frequency.

http://www.golovchenko.org/cgi-bin/delay