Msg: 4455 *Conference*

06-24-93 16:51:32

From: TRACY ALLEN

To : DAVID FIRTH

Subj: REPLY TO MSG #4441 (I/O INTERFACE)

Well, tie a magnet to the seconds hand of a clock, then have the magnet pass by
a magnetic reed  switch, tied to the gate of the SCR.  Not!   A
crytal-controlled clock would be a better idea.  How often do you have to wake
the machine up?  In my data loggers, data is recorded once per hour.  The RC
interval for wake-up is about 2 minutes.  The computer when it wakes up, tests
if it is less than two minutes to go to the hour.  If so, it stays awake until
the hour mark.  That way it achieves accurate timing based on the T102 clock,
but uses the RC for the wake-up cycle.  The average current consumption is just
a couple of milliamps instead of 70 milliamps.
  -- Tracy