Kindly Suggest a cheap RTC unit that has a battery backup

arunb · Joined: 08 Sep 2003 Posts: 492 Location: India

Hi,

MCU: 16F628, 16F877
Compiler: PCM 3.169

At present I am using a 32.768 Khz clock to keep time, one makor problem with this method is synchronisation, are there any RTC units available that have an in built memory backup ( or internal battery) .

I was told MAX had such a unit, but I am not sure....

thanks
arunb

Guest · Posted: Fri Jun 03, 2005 8:31 am

Maxim dallas do a LOT of RTC's. I've used teh DS1307, 1337 and 1339 and been very satisfied with tehm. The 1305 and 1339 allow external backups from a battery coin cell which is probably what you want. Have a look around the Maxim dallas site for ideas. I'm sure they'll have something you need-JBM

treitmey · Joined: 23 Jan 2004 Posts: 1094 Location: Appleton,WI USA

Don't know about price,... but I've just played with and wrote dirvers for the DALLAS DS12887. BATTERY BUILT IN WITH CHARGING CURCUIT. Holds time for 10 years with out power. Seems to work great.

Just pulled the specs from my head. So verifly them.

The downfall of this one is it takes a bunch of pins. If they have a simular one that talks on the I2C bus, go with that one.

Joven · Guest

Hi

treitmey you can share the DALLAS DS12887 driver?
I find one an old motherboard and want try connecto 16f877A.

bwhiten · Joined: 26 Nov 2003 Posts: 151 Location: Grayson, GA

I have used the DS1307 with a small button battery several times and it is I2C. Small package and easy to use as well.

Joven · Guest

i cant find the driver for ds12887.

if someone have can post?

thaks

treitmey · Joined: 23 Jan 2004 Posts: 1094 Location: Appleton,WI USA

http://www.ccsinfo.com/forum/viewtopic.php?p=67343#67343

Joven · Guest

Hi.

Can put a exemple of the connections od ds12887 rtc some pic (ex. 16f877)

thanks