slow response of DS1307

Hi all

I am interfacing the DS1307 chip with AT89c51 and i have a problem in reading RTC registers.While reading the seconds register, it increments after every 4 seconds.Since i am not using the battery backup, i have grounded the corresponding pins (VBat),Could anyone of you suggest me how to overcome this problem.

Thanking in advance.

Regards Arun.

"jessy" schreef in bericht news: snipped-for-privacy@i3g2000cwc.googlegroups.com...

Strange. Are you sure the serial data isn't shifted by 2 bits by mistake, for some reason?

On 03/09/2006 the venerable jessy etched in runes:

DS1307 works fine on my mega32 board from Futurlec. I suggest you change to an AVR >:-}

Are you sure frequency is exactly 32768Hz ?

You HAVE to use a battery!

Regards Ulrich

"jessy" schrieb im Newsbeitrag news: snipped-for-privacy@i3g2000cwc.googlegroups.com...

"Ulrich Bangert" schreef in bericht news:edgcfm$oe2$03$ snipped-for-privacy@news.t-online.com...

Not according to the datasheet. The datasheet advices to connect the battery pin to ground, if not used.

-- Thanks, Frank. (remove 'q' and '.invalid' when replying by email)

Make sure the crystal is 6pF and not 12pF.

Regards Anton Erasmus

Are you handling the I2C start, stop, and ACKs correctly? The 1307 latches the time when you isssue an I2C START condition maybe you are not sending the ACK or STOP conditions right and the latched value is hanging around until you hit the "magic" combination in your read code again. Just a guess, have 100's of 1307s out there all update fine......

Jim