> > Are there uPs with clock/calendar as an internal feature ?
The DS5000 has this, but it's a pricey brick.
You can do it yourself in the micro really if you don't need long term
accuracy, or use one of a number of RTC chips on the market.
Duilio Foschi a icrit :
>
> Are there uPs with clock/calendar as an internal feature ?
>
Micromint has bundled up a PIC16x84 with diverse combination of: 12-bit
ADC, 12-bit DAC and real-time clock on what they call PicStic. http://www.micromint.com
> Micromint has bundled up a PIC16x84 with diverse combination of:
> 12-bit ADC, 12-bit DAC and real-time clock on what they call PicStic.
> http://www.micromint.com
> Are there uPs with clock/calendar as an internal feature ?
> Is it advisable to use an external clock/calendar chip anyway ?
The chief advantage is that the purpose-built clock chips have
extremely low current consumption. We are talking applications where
the device is battery powered and the main CPU is shut down much of the
time, aren't we?
The larger PICs, AVRs and others have a low-power secondary counter
to operate from a 32,768 Hz "watch" crystal (you must carefully match
the crystal parameters to the circuit to keep proper time), so that the
chip is woken by an interrupt each second, counts the seconds and goes
back to sleep.
This process is limited in effectiveness by the time taken to start
up, during which the chip is of course drawing its full "running"
current, and the residual current consumption of the "sleep" mode. An
external clock chip may be used to allow the MCU completely shut down,
perhaps even be cut off from the supply if this achieves lower current,
and you do not have these current "burps" each second.
--
Cheers,
Paul B.
You might try using the DalSemi Ibutton / Thermochron. http://www.ibutton.com
it has temp/rtc/ram in a can that fits in a coin battery holder and only
needs 1 pin to communicate. 10year life on Lithium battery in the can.
joe
Duilio Foschi wrote:
>
> Are there uPs with clock/calendar as an internal feature ?
>
> Is it advisable to use an external clock/calendar chip anyway ?
>
> Thank you
>
> Duilio Foschi
Paul B. Webster VK2BZC wrote:
>
> Gaston Gagnon wrote:
>
> > Micromint has bundled up a PIC16x84 with diverse combination of:
> > 12-bit ADC, 12-bit DAC and real-time clock on what they call PicStic.
> > http://www.micromint.com
>
> Or of course http://www.dontronics.com/dt101.html
At 03:49 PM 9/11/99 +0200, you wrote:
>Are there uPs with clock/calendar as an internal feature ?
>
>Is it advisable to use an external clock/calendar chip anyway ?
>
>Thank you
>
>Duilio Foschi
Seems to me that with the complexity of a standard microchip you ought to
be able to program the clock calender stuff in quite easily. I know that
somewhere you can find the big honking formula that sets it all out. I
can't imagine it being more than a couple hundred instructions to
implement. Then all that is left is to count seconds : 32.768kHz crystal,
a cmos inverter, a 15 bit divider, and some caps and resistors....
Seems like that's all that would be necesary to do it in software.
dontronics.com http://www.dontronics.com