Err, for a RTC device, I suppose you can drop the write-polling hehe.
(I was a little too quick there.)

Instead, check the data-sheet to find if you are using too short hold-time
on data/clock.
Some slower circuits require a longer clock-high than clock-low (or
vise-versa).

    KreAture


----- Original Message -----
From: "Rajiv Thakur" <rajiv_thakur@VSNL.COM>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Monday, February 10, 2003 7:51 PM
Subject: [PIC]: 100KHz I2C vs 400 KHz - Ds 1307 RTC


> I have tried 3  I2C (in assembly) routines successfully programming 24C02-
> 24C16 eproms , to program RTC DS 1307 through a 16F877 /4Mz. I find that
> all the routines  are inconsistent in writing and reading the RTC (
success
> rate of 70%) while they successfully program the 24Cxx.
>
> Perhaps this is due to  the fact that the datasheet of DS1307 says it
works
> only on 100 KHz I2C and not on 400KHz I2C . I am unable to get any
> improvement in performance even by adding delays suggested by some sites
> searched through Google.
>
> Any advice for solving this problem is welcome.
>
> Thanks in advance
>
> Rajiv Thakur
>
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