Method and circuit for allowing a microprocessor to change its operating frequency on-the-fly

摘要

A circuit that permits a processor in a microcontroller to adjust its clock speed on the fly. A processor receives a current clock signal and a phased current clock signal from a speed selection switch. A new speed selection switch provides a new clock signal and a phased new clock signal for comparison with the current clock signals. When the states of the current and new clocks appropriately align after issuance of a control from the processor, the new speed is switched into the current speed switch to permit the clock speed to change without producing spurious signals that cause unpredictable action in the processor. This advantageously allows the microcontroller to adjust its clock speed under program control.