

Abstract: Electronic Elapsed Time Monitor

This simple system provides a demonstration of a bare-bones DT-104
and the discrete I/O and EEPROM features of the 90S1200.
It might have practical use as a "maintenance needed" indicator for
construction equipment or similar items not otherwise equipped to log
operating time. The single input is used to reset the elapsed time.
Two pins are set as outputs and drive LEDs.

During normal operation the green LED flashes to provide an "ON"
indication. The internal EEPROM tracks total operation time and is
updated every 6 minutes. The yellow LED is off when elapsed time
is less than 50 hours, flashing for times from 50 up to but
not including 60 hours, and continuously on for times of 60 hours
or more.


