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DS1302 time keeping chip — Parallax Forums

DS1302 time keeping chip

larryp1larryp1 Posts: 8
edited 2014-07-22 12:01 in Accessories
I want to build some sensors for a weather balloon and I need to time stamp the time the observation was made. I am considering using the DS1302. Will the chip remember the time when power is removed from the cirsuit or does it need to be re-initialized each time the sensors are started?

Comments

  • NWCCTVNWCCTV Posts: 3,629
    edited 2014-07-21 21:08
    The DS1302 is designed to operate on very low power, and retain the data and clock information on less than 1 µW.
    From the main page. It looks to me that it needs at least 1 µW power to properly keep time. However, I may be wrong.
  • JLockeJLocke Posts: 354
    edited 2014-07-21 22:11
    Generally you're going to want some type of battery-backup to retain the date/time when power is removed. A small coin cell is usually used.
  • Sir GawainSir Gawain Posts: 32
    edited 2014-07-22 08:06
    I have used this chip in various projects and found that it can work with a capacitor as the backup battery. This is not heavy, although a little less reliable.
    I like the "full" driver.
    http://obex.parallax.com/object/14
  • tomcrawfordtomcrawford Posts: 1,126
    edited 2014-07-22 10:13
    I think the cap backup is more "elegant" (whatever I think that means) than a battery. Also, they are as little as $1.09 at Jameco as opposed to a coin cell plus a battery holder. And I KNOW they last long enough to keep time while being mailed from California to Arizona!
  • PublisonPublison Posts: 12,366
    edited 2014-07-22 12:01
    Parallax is using a "Super Cap" on their new GPS instead of a battery. It's a SMD 30Mf 3.3 device.

    No..I can not share. :)
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