Patent ID: 6019500
Filing Date: 2000-02-01
Classification: G07C

Abstract:
A method for measuring cumulative time in a digital signal processing system, the method comprising the steps of:determining a time constant A representing a cumulative time updating increment;determining a correction factor time constant a representing an average error of cumulative time each time an electric source of an electrical piece of equipment is turned on, wherein a is generally one-half of A;starting a measurement of cumulative time when the electric source of the electrical piece of equipment is turned on;preparing a plurality of writing portions in an EEPROM, each writing portion equaling a minimum unit time data of cumulative time data T.sub.s ;initially adding A to the plurality of writing portions wherein A is added to the cumulative time data T.sub.s previously stored in the plurality of writing portions to make an added value;storing the added value in the plurality of writing portions as said cumulative time data T.sub.s at a time when the measurement of cumulative time becomes (A-a); andrepeatedly adding A to the cumulative time data T.sub.s stored in the plurality of writing portions to make an updated added value and storing the updated added value in the plurality of writing portions as the cumulative time data T.sub.s at each increment A of the measurement of cumulative time after the step of adding A.