PIC and RTC DS1307 problem - hardware vs software ?

[Steve_88]

Good luck, let us know of it helps. A clue for me was that the clock only reset after removing/applying power.

[jorge]

Unfortunately it still happens…
and also sometimes it freezes time in some modules, the main controller still working ok but the clock info freezes on the LCD (this is not fault of the main PIC18F as the other routines and peripheral are working ok).

I am beginning to hate these DS1307 chips …
The strange thing is that this only happen in some units, and I am not able replicate the problem in the lab.

Anyone had problems with time being freeze in the RTC for no reason?!

[Charles Linquis]

I had a similar issue several years ago with a 1307. I can't explain exactly what the problem was, but putting a 1uF very low-leakage cap across the battery solved the problem. An added benefit was that - if you were quick, you could change the battery without clearing the clock. The chip will run on the capacitor alone for 10-20 seconds. The cap has to be low-leakage, otherwise it will drain the battery.

[pedja089]

That problems can cause static electricity, or arcing in relays etc. You should put 100nF 10nF and 1nF capacitor, close to power pins.

[jorge]

I had a similar issue several years ago with a 1307. I can't explain exactly what the problem was, but putting a 1uF very low-leakage cap across the battery solved the problem. An added benefit was that - if you were quick, you could change the battery without clearing the clock. The chip will run on the capacitor alone for 10-20 seconds. The cap has to be low-leakage, otherwise it will drain the battery.

I cant find a cap like the one you said - 1uF very low-leakage cap-
i tried at Farnell, digikey and so on...but if you could provide me a direct link or even a full spec of one would be great..otherwise i am afraid of it draining the battery !

Also i already have lots of caps both in the power supply , lots of 100nf on the pcb board, the standard ones on LM7805 , and so on..
My biggest problem is that i cannot simulate it , and as so i cant provide a valid software workaround to the RTC stop/ it just freezes time without any reason.
( note: i ve already replaced the board and the DS1307, check the value of all the resistors ( 10K ) , check and changed the RTC OSC, redesign PCB in terms of ground and power lines, check solders, and so on....felling lost now)

thanks for your help.

note:
Darrel , MisterE , & other PRO´s: any miracle software workaround you can think for this -the freeze time on the RTC ? Maybe using the PIC EEprom and an pic check stall time function...i am just worried that this way i will kill my EEPRom sooner or later
I already have a auto set date/time when it has garbage settings inside but not when it simply stops without a reason.
Damm i hate these DS1307 things

[Charles Linquis]

The cap we use is actually a .47 uF ceramic

TDK P/N C3216X8R1H474K