Real Time Pics

[Robert]

With the Pics, I believe it is possible to purchase a chip that can display
real time.

Dose anybody know what this chip is or where it can be purchased.

Thanks Robert

 

[cdb]

None of the current Pics have a RTC register such as that found in the
Renesas (Hitachi) 3672.

However, those Pics with a Timer1 register - 16F87x, 16F630, 16F80 and all
the 18F series, do have the option of having an external 32.768KHz crystal
as a time base for timer1 and from this an RTC can be fashioned.

If your Pic doesn't have a Timer1 register, then there is an algorithm,
using a 24bit register that will allow for an RTC with less jitter than that
provided by an external crystal.

I have a Water useage meter with combined Sprinkler controller that uses
this Bresenham algorithm, and have had no problems as far as inacurracy is
concerned.

Of course another way is to 'borrow' the 50Hz mains frequency as the
timebase.

Colin

 

[Vermin]

None of the current Pics have a RTC register such as that found in the
Renesas (Hitachi) 3672.

Wrong. The PIC16F7x7 range feature an RTC.

V.

 

[Vermin]

Wrong. The PIC16F7x7 range feature an RTC.

Actually you are right, Microchip misled me.

The December 03 Microchip newsletter indicated that these chips had an
on board RTC.

Reading the datasheet shows that this is actually performed in
software using TMR1!

V.