Method of controlling clock signal
A method of controlling a clock signal with a print controller is provided. In response to receiving an external signal, the print controller determines the number of cycles of a clock signal generated by a ring oscillator of the print controller during a predetermined number of cycles of the external signal or the number of cycles of the external signal during a predetermined number of cycles of the clock signal and outputs the determined number of cycles to an external circuit. In response to receiving a trim value from clock trim circuitry of the print controller which trims the frequency of the clock signal based on the determined number of cycles from the external circuit, the trim value is stored in memory of the print controller. The clock trim circuitry is controlled to trim the frequency of the clock signal generated by the ring oscillator using the trim value.
1. A method of controlling a clock signal with a print controller, the method comprising the steps of:
in response to receiving an external signal, the print controller determining the number of cycles of a clock signal generated by a ring oscillator of the print controller during a predetermined number of cycles of the external signal or the number of cycles of the external signal during a predetermined number of cycles of the clock signal and outputting the determined number of cycles to an external circuit;
in response to receiving a trim value from clock trim circuitry of the print controller which trims the frequency of the clock signal based on the determined number of cycles from the external circuit, storing the trim value in memory of the print controller; and
controlling the clock trim circuitry to trim the frequency of the clock signal generated by the ring oscillator using the trim value.
2. The method according to claim 1 , wherein the memory incorporates non-volatile memory, wherein the method includes storing the trim value in the non-volatile memory.
3. The method according to claim 2 , where the non-volatile memory is flash RAM, wherein the method includes storing, using a flash write, the trim value to the non-volatile memory.
4. The method according to claim 1 , wherein the clock trim circuitry incorporates a register, wherein the method includes, in the processor, loading the trim value from the memory into register.
5. The method according to claim 1 , wherein the method includes storing the trim value permanently in the integrated circuit.
6. The method according to claim 1 , wherein the method includes operating the integrated circuit under conditions in which the signal for which the number of cycles is being determined is at a considerably higher frequency than the other signal.
7. The method according to claim 6 , wherein the method includes operating the integrating circuit when a ratio of the number of cycles determined and the predetermined number of cycles is greater than about 2.
8. The method according to claim 7 , wherein the ratio is greater than about 4.
9. The method according to claim 1 , wherein in the method includes compensating the trim value based upon a temperature of the integrated circuit during the determination of the number of cycles.