Patent ID: 6618456
Filing Date: 2003-09-09
Classification: H04L

Abstract:
An asynchronous timing oscillator re-synchronizer which enables a high frequency clock used to measure time intervals in a clocked system to be temporarily disabled without significant loss of timing accuracy, comprising:a clock ratio register arranged to, for a clocked system which receives a high frequency clock and a low frequency clock and which normally measures time intervals with said high frequency clock, periodically store a clock ratio given by the number of high frequency clock cycles that occur during a predetermined number of low frequency clock cycles; a clock-disable counter connected to receive said low frequency clock and a clock-disable command which indicates that said high frequency clock is to be disabled for a disablement period defined as a specified number of low frequency clock cycles as inputs, said clock-disable counter arranged to, upon receipt of said clock-disable command, output a signal which disables said high frequency clock, begin counting low frequency clock cycles, and output a signal which re-enables said high frequency clock when said specified number of low frequency clock cycles has occurred; and a missing high frequency clock cycles register which receives said low frequency clock and a signal which indicates that said high frequency clock is disabled as inputs, said missing high frequency clock cycles register arranged to, while said high frequency clock is disabled, periodically increment the value stored in its register by said clock ratio such that the number stored in said missing high frequency clock cycles register when said high frequency clock is re-enabled represents the number of high-frequency clock cycles that would have occurred during said disablement period, said number stored in said missing high frequency clock cycles register at the end of said disablement period provided to said clocked system and enabling said clocked system to be re-synchronized with said high frequency clock.