Method and apparatus for providing a soft clock re-sync for subscriber line interface cards
View Patent ↗A first clock signal is generated by a first circuit and a second clock signal is generated by an auxiliary clock circuit. A switch controls whether the first clock signal or the second clock signal is provided to a subscriber line integrated circuit (SLIC). The SLIC is operable to generate a line voltage within predetermined tolerances on a loop line at a customer premises if the SLIC is receiving the first clock signal or the second clock signal. A resync signal is sent to the SLIC to cause it to resync with the first clock signal without going through a reset operation.
1. An apparatus comprising:
a microprocessor providing a first clock signal;
an auxiliary clock circuit generating a second clock signal;
a subscriber line integrated circuit (SLIC) generating a line voltage on a loop line if the SLIC is receiving the first clock signal or the second clock signal; and
a switch controlling whether the SLIC receives the first clock signal or the second clock signal based on instructions from the microprocessor,
wherein when the microprocessor instructs the switch to provide the first clock signal to the SLIC, after providing the second clock signal to the SLIC, the SLIC resynchronizes with the first clock signal without being reset.
2. The apparatus of claim 1 , wherein the microprocessor instructs the switch to provide the second clock signal to the SLIC when the microprocessor detects a soft reset.
3. The apparatus of claim 2 , wherein the microprocessor instruct the switch to provide the first clock signal to the SLIC when the microprocessor completes a reset operation.
4. The apparatus of claim 1 , wherein the SLIC contains a phase lock loop which synchronizes a SLIC clock based on a received first clock signal or second clock signal.
5. The apparatus of claim 1 , wherein the switch is contained in the SLIC and the microprocessor provides instructions to switch by a dedicated connection to the SLIC.
6. A method of resynchronizing a clock in a SLIC comprising the steps of:
detecting that a microprocessor has completed a soft reset operation;
providing a clock signal from the microprocessor to the SLIC after completing the soft reset operation; and
sending instructions to a switch associated with the SLIC to provide the clock signal from the microprocessor to the SLIC,
wherein the SLIC synchronizes with the clock signal from the microprocessor without being reset.
7. The method of claim 6 , wherein an auxiliary clock is provided to the SLIC when the microprocessor detects a soft reset.
8. The method of claim 7 , wherein the clock signal from the microprocessor is provided to the SLIC when the microprocessor completes a reset operation.
9. The method of claim 6 , wherein the SLIC contains a phase lock loop which synchronizes a SLIC clock based on received clock signal from the microprocessor or the second clock signal.
10. The method of claim 6 , wherein the switch is contained in the SLIC and the microprocessor provides instructions to switch by a dedicated connection to the SLIC.
11. A non-transitory computer readable medium carrying instructions to cause a computer resynchronize a clock in a SLIC, the instructions comprising instructions to perform the steps of:
detecting that a microprocessor has completed a soft reset operation;
providing a clock signal from the microprocessor to the SLIC after completing the soft reset operation; and
sending instructions to a switch associated with the SLIC to provide the clock signal from the microprocessor to the SLIC,
wherein the SLIC synchronizes with the clock from the microprocessor without being reset.
12. The non-transitory computer readable medium of claim 11 , wherein an auxiliary clock signal is provided to the SLIC when the microprocessor detects a soft reset.
13. The non-transitory computer readable medium of claim 12 , wherein the clock signal from the microprocessor is provided to the SLIC when the microprocessor completes a reset operation.
14. The non-transitory computer readable medium of claim 11 , wherein the SLIC contains a phase lock loop which synchronizes a SLIC clock based on a received first clock signal or a second clock signal.
15. The non-transitory computer readable medium of claim 11 , wherein the switch is contained in the SLIC and the microprocessor provides instructions to switch by a dedicated connection to the SLIC.