Method and apparatus for generating a clock signal and for controlling a clock frequency using the same
A method and a device for generating a clock signal determine a number of pulses to be discarded from each predetermined cycle of a reference clock signal in order to obtain, on average, a target frequency. A masking pattern is created for discarding the number of pulses to be discarded from each predetermined cycle of the reference clock signal. The clock signal, which includes the target frequency, is generated by discarding the number of pulses from the reference clock signal using the masking pattern.
1. A method of controlling a clock frequency, the method comprising:
generating a clock signal for an application having, on average, a target frequency from a reference clock signal;
calculating a data processing progress percentage of processing data using the clock signal;
determining a difference between the calculated data processing progress percentage and a target progress percentage; and
changing the target frequency of the clock signal based on the determined difference.
2. The method of claim 1 , wherein generating the clock signal for the application comprises discarding a calculated number of pulses from each of a plurality of sections of the reference clock signal, so that the reference clock signal comprises, on average, the target frequency.
3. The method of claim 1 , wherein generating the clock signal for the application comprises:
calculating a pulse detecting location in a plurality of cycles of the reference clock signal, a number of pulses of a cycle corresponding to an inverse of the target frequency; and
detecting a pulse of the reference clock signal closest to the calculated pulse detecting location.
4. The method of claim 1 , wherein changing the target frequency of the clock signal comprises:
decreasing the target frequency of the clock signal when the calculated progress percentage is greater than the target progress percentage by a first predetermined amount; and
increasing the target frequency of the clock signal when the calculated progress percentage is less than the target progress percentage by a second predetermined amount.
5. A device for controlling a clock frequency, the device comprising:
a clock signal generating circuit configured to generate a clock signal for an application, the clock signal having a target frequency from a reference clock signal;
an application circuit configured to process data using the clock signal for the application; and
a microprocessor configured by software to provide instructions for calculating a data processing progress percentage of the application circuit and for controlling the clock signal generating circuit to change the target frequency based on a difference between the calculated data processing progress percentage and a target progress percentage.
6. The device of claim 5 , wherein the clock signal generating circuit comprises:
a masking pattern generator configured to create a masking pattern to discard at least one pulse from the reference clock signal to obtain the target frequency from the reference clock signal; and
an AND gate configured to generate the clock signal for the application by logically multiplying the reference clock signal and the masking pattern.
7. The device of claim 5 , wherein the clock signal generating circuit comprises:
an arithmetic circuit configured to calculate a pulse detecting location in a plurality of cycles, each cycle comprising a number of pulses corresponding to an inverse of the target frequency of the clock signal for the application; and
a pulse detector configured to detect a pulse of the reference clock signal generated closest to the pulse detecting location.
8. The device of claim 5 , wherein the microprocessor is further configured by software to provide instructions for controlling the clock signal generating circuit to decrease a frequency of the clock signal when the calculated progress percentage is greater than the target progress percentage by a first predetermined amount, and for increasing the frequency of the clock signal when the calculated progress percentage is less than the target progress percent by a second predetermined amount.