Trouble with DS1307 battery backup

[Amoque]

I am currently working with a DS1307 RTC ('877A and I2C). All is well reading, writing, and displaying result to a typical LCD. The difficulty comes when using a battery (2032 Lithium coin) to backup the clock. Insert the battery, the display flashes: 04:04:04; remove it, time returns to accurate display and advance. Re-insert battery, display reads: 04:04:04... Its quite a fun game, but not very efficient way to keep the time. I've checked the voltage of the battery, wiring, and everything else I can think of - as well as tried some basic filtering. I've searched Google for any known issues and found nothing... Anyone can advise?

[SUNFLOWER]

A schematic showing DS1307, never had trouble except once when a circuit mistake overheated the voltage supply and the clock with battery gave similar data.

http://www.harbornet.com/sunflower/PCB.jpg

[aratti]

Very likely a wiring problem. Did you place two diodes to isolate the battery from power?

You can have more help if you post the schematic.

Cheers

Al.

[aerostar]

Very likely a wiring problem. Did you place two diodes to isolate the battery from power?


Al.

You do not need your suggested diodes - if you look at the data sheet the backup battery has its own pin, and the battery should be connected to that and ground.

[Amoque]

I was thinking more like stray capacitance issues, or I2C resisters of wrong value (3K3)- something of that nature; maybe battery back-up voltage (3.32V) issue. Wiring the battery could hardly be easier and I've looked, until my eyes crossed, at the holder to be sure there was nothing wrong with it. I think I'll try a different battery, but I've already tried a different 1307 and a different 12.5 pF crystal, verified wiring- exact same result. Circuit is rock solid, just goes "404" on me when the battery is inserted.

[mackrackit]

What happens if you leave the battery inserted? Can you then reprogram the time?