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Dallas Semi 1302 timekeeper-alternative? — Parallax Forums

Dallas Semi 1302 timekeeper-alternative?

ArchiverArchiver Posts: 46,084
edited 2004-01-21 23:30 in General Discussion
I saw a reference somewhere that said the DS1302 is now obsolete.
Can anyone recommend a direct replacement from DS-Maxim that has the
same 3-wire interface but includes the crystal and has the onboard
battery backup?

thanks, Steve Hinote

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2004-01-21 01:27
    woops. turns out the obsolete reference was to the 1-wire DS1820
    Digital Thermometer (not the DS1302 timekeeper).

    But I'd still like to hear if someone found an upgrade to the DS1302.

    thanks


    --- In basicstamps@yahoogroups.com, "stenote" <stepnote@c...> wrote:
    > I saw a reference somewhere that said the DS1302 is now obsolete.
    > Can anyone recommend a direct replacement from DS-Maxim that has
    the
    > same 3-wire interface but includes the crystal and has the onboard
    > battery backup?
    >
    > thanks, Steve Hinote
  • ArchiverArchiver Posts: 46,084
    edited 2004-01-21 01:53
    my favorite is the Dallas DS1307 because its 2-wire I2C bus compatible.
    however it still requires an external 32KHz cystal and battery backup.
    search Digikey for the part and datasheet.


    At 07:27 PM 1/20/2004, you wrote:
    >woops. turns out the obsolete reference was to the 1-wire DS1820
    >Digital Thermometer (not the DS1302 timekeeper).
    >
    >But I'd still like to hear if someone found an upgrade to the DS1302.
    >
    >thanks
    >
    >
    >--- In basicstamps@yahoogroups.com, "stenote" <stepnote@c...> wrote:
    > > I saw a reference somewhere that said the DS1302 is now obsolete.
    > > Can anyone recommend a direct replacement from DS-Maxim that has
    >the
    > > same 3-wire interface but includes the crystal and has the onboard
    > > battery backup?
    > >
    > > thanks, Steve Hinote
    >
    >
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  • ArchiverArchiver Posts: 46,084
    edited 2004-01-21 03:07
    I like the dallas 2404 econoRAM timekeeper chip. It has a 1-wire or a
    3-wire interface, 4096 bits (512 bytes) of NVRAM, as well as timekeeper
    functions(including an alarm interrupt). I think Digikey has these.
    Also, if you can do 1-wire (BASIC STAMP 2p), there is the Dallas1994,
    which is essentially a 2404 in a 1-wire can (these are my favourites),
    the only way I've been able to get these is to order samples from
    Maxim/Dallas. JDR used to have them, but not any more. Be careful with
    the startup sequence. If you do it wrong you can lock up the chip and
    render it useless...read the data sheet CAREFULLY!

    chris in napa

    stenote wrote:

    >I saw a reference somewhere that said the DS1302 is now obsolete.
    >Can anyone recommend a direct replacement from DS-Maxim that has the
    >same 3-wire interface but includes the crystal and has the onboard
    >battery backup?
    >
    >thanks, Steve Hinote
    >
    >
    >To UNSUBSCRIBE, just send mail to:
    > basicstamps-unsubscribe@yahoogroups.com
    >from the same email address that you subscribed. Text in the Subject and Body
    of the message will be ignored.
    >
    >
    >Yahoo! Groups Links
    >
    >To visit your group on the web, go to:
    > http://groups.yahoo.com/group/basicstamps/
    >
    >To unsubscribe from this group, send an email to:
    > basicstamps-unsubscribe@yahoogroups.com
    >
    >Your use of Yahoo! Groups is subject to:
    > http://docs.yahoo.com/info/terms/
    >
    >
    >
    >
  • ArchiverArchiver Posts: 46,084
    edited 2004-01-21 21:52
    thanks for a couple good comments...I'm starting to think I'll stick
    with the 1302, it's working OK. now I like the idea of using the
    DS32KHZ temp compensated oscillator with the 1302, and a supercap.

    My only problem is I haven't yet found a reference about what cap
    value to use, or for that matter what a supercap is.

    can anyone shed some light on "what supercap should be used to
    backup the DS1302 RTC"

    steve hinote


    --- In basicstamps@yahoogroups.com, Chris Burns <mwalimu@s...> wrote:
    > I like the dallas 2404 econoRAM timekeeper chip. It has a 1-wire
    or a
    > 3-wire interface, 4096 bits (512 bytes) of NVRAM, as well as
    timekeeper
    > functions(including an alarm interrupt). I think Digikey has
    these.
    > Also, if you can do 1-wire (BASIC STAMP 2p), there is the
    Dallas1994,
    > which is essentially a 2404 in a 1-wire can (these are my
    favourites),
    > the only way I've been able to get these is to order samples from
    > Maxim/Dallas. JDR used to have them, but not any more. Be
    careful with
    > the startup sequence. If you do it wrong you can lock up the chip
    and
    > render it useless...read the data sheet CAREFULLY!
    >
    > chris in napa
    >
    > stenote wrote:
    >
    > >I saw a reference somewhere that said the DS1302 is now
    obsolete.
    > >Can anyone recommend a direct replacement from DS-Maxim that has
    the
    > >same 3-wire interface but includes the crystal and has the
    onboard
    > >battery backup?
    > >
    > >thanks, Steve Hinote
    > >
    > >
    > >To UNSUBSCRIBE, just send mail to:
    > > basicstamps-unsubscribe@yahoogroups.com
    > >from the same email address that you subscribed. Text in the
    Subject and Body of the message will be ignored.
    > >
    > >
    > >Yahoo! Groups Links
    > >
    > >To visit your group on the web, go to:
    > > http://groups.yahoo.com/group/basicstamps/
    > >
    > >To unsubscribe from this group, send an email to:
    > > basicstamps-unsubscribe@yahoogroups.com
    > >
    > >Your use of Yahoo! Groups is subject to:
    > > http://docs.yahoo.com/info/terms/
    > >
    > >
    > >
    > >
  • ArchiverArchiver Posts: 46,084
    edited 2004-01-21 23:30
    From: "stenote" <stepnote@c...>

    > My only problem is I haven't yet found a reference about what cap
    > value to use, or for that matter what a supercap is.
    >
    > can anyone shed some light on "what supercap should be used to
    > backup the DS1302 RTC"
    >
    A "supercap" refers to a fairly recent development in the process technology
    used to produce capacitors. (Well, fairly recent to an old fogy anyway.) It
    makes it practical to build capacitors with values in the whole farad range.
    Traditional caps have run from picofarads to microfarads. (That's billionths
    of a farad to the millionth of a farad range.) One farad is an enormous
    capacitance by comparison, and makes it practical to store as much energy as
    small batteries do.

    You can find these under names like "Supercap", "Capattery" and probably
    others that I haven't noticed. Here's one at Mouser with roughly a half
    farad capacitance for two bucks: http://makeashorterlink.com/?B3A313527
    and another at Digikey with a whole farad for less than four dollars:
    http://makeashorterlink.com/?P2C312527

    Both of those are 5V because I assume that's about what you need. I don't
    feel like doing the arithmetic, but I'd guess a one farad cap would back up
    the DS1302 for half an eternity or so. Give or take an eon.

    Gary
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