MICROCOMPUTER AND METHOD FOR CORRECTING CLOCK THEREOF

摘要

A sub clock 20 counts oscillating pulses of a CR oscillating circuit 21 by a loop counter 22, and outputs a clock signal each time the oscillating pulses reach a target count Pm. A CPU 11 counts oscillating pulses of the CR oscillating circuit 21 in a predetermined time measured by a time counter 25 in response to a dock signal of a main clock 13 by a crystal oscillator, and corrects the target count Pm according to a pulse count P thereof. Since the real count state is obtained based upon the clock signal of the main clock having high frequency accuracy without the estimation of the sub clock 20, the high accuracy of the sub clock is retained even if environmental changes such as temperatures occur.

主权项

1. A microcomputer including at least one clock comprising:
a reference data obtaining unit configured to obtain count data from a reference clock signal source higher in frequency accuracy than the clock; a measuring unit configured to measure count data of the clock on a basis of the count data from the reference clock signal source; a memory for storing the count data of the clock; and a correcting unit configured to correct a clock signal of the clock based upon the measured result by the measuring unit; wherein the measuring unit operates the clock by a predetermined time interval at a regular operating mode of a CPU to measure the count data of the clock and store the count data of the clock in the memory, and the correcting unit corrects the clock signal of the clock using the latest count data of the clock stored in the memory at the transfer from the regular operating mode to a sleep mode.