Method and apparatus for data communication and storage wherein a IEEE1394/firewire clock is synchronized to an ATM network clock
First Claim
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1. A data communication system for data communication between a serial bus and an ATM (Asynchronous Transfer Mode) network, the data communication system comprising:
- first interface means for performing interface processing for said bus;
second interface means for performing interface processing for said network; and
generating means for generating a first clock used by said first interface means as a cycle master clock for said bus in synchronization with a second clock used as a reference clock for said ATM network;
whereby said first clock is generated by a phase locked loop wherein the phase of a frequency-divided version of said first clock is compared to the phase of said second clock and the frequency of said first clock is adjusted according to the result of the phase comparison.
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Abstract
The present invention relates to a data communication system for data communication between a bus and a network. This data communication system of the present invention includes a first interface device for performing interface processing for the bus, a second interface device for performing interface processing for the network, and a generating device for generating a first clock used by the first interface device in synchronization with a second clock used for causing processes in the network to be synchronized.
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Citations
9 Claims
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1. A data communication system for data communication between a serial bus and an ATM (Asynchronous Transfer Mode) network, the data communication system comprising:
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first interface means for performing interface processing for said bus;
second interface means for performing interface processing for said network; and
generating means for generating a first clock used by said first interface means as a cycle master clock for said bus in synchronization with a second clock used as a reference clock for said ATM network;
whereby said first clock is generated by a phase locked loop wherein the phase of a frequency-divided version of said first clock is compared to the phase of said second clock and the frequency of said first clock is adjusted according to the result of the phase comparison. - View Dependent Claims (2, 3)
said bus is an IEEE1394 serial bus.
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3. A data communication system according to claim 1, further comprising:
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control means for controlling said first interface means and said second interface means; and
frequency-dividing means for generating an interrupt control signal provided to said control means by performing frequency-division on said second clock.
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4. A data communication method for data communication between a serial bus and an ATM (Asynchronous Transfer Mode network, the data communication method comprising:
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a first interfacing step for performing interface processing for said bus;
a second interfacing step for performing interface processing for said network; and
a generating step for generating a first clock used by said first interfacing step as a cycle master clock for said bus in synchronization with a second clock used as a reference clock for said ATM network;
whereby said first clock is generated by a phase locked loop wherein the phase of a frequency-divided version of said first clock is compared to the phase of said second clock and the frequency of said first clock is adjusted according to the result of the phase comparison.
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5. A data communication system for data communication between a serial bus and an ATM (Asynchronous Transfer Mode) network, the data communication system comprising:
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first interface means for performing interface processing for said serial bus;
second interface means for performing interface processing for said network; and
generating means for generating a first clock used by said first interface means as a cycle master clock for said bus in synchronization with a second clock used as a reference clock for said ATM network;
whereby said first clock is generated by a phase locked loop wherein the phase of a frequency-divided version of said first clock is compared to the phase of said second clock and the frequency of said first clock is adjusted according to the result of the phase comparison; and
whereby the frequency of said first clock is based on a frame timing signal used by said network.
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6. A data communication method for data communication between a serial bus and an ATM (Asynchronous Transfer Mode) network, the data communication method comprising:
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a first interfacing step for performing interface processing for said serial bus;
a second interfacing step for performing interface processing for said network; and
a generating step for generating a first clock used by said first interfacing step as a cycle master clock for said bus in synchronization with a second clock used as a reference clock for said ATM network;
whereby said first clock is generated by a phase locked loop wherein the phase of a frequency-divided version of said first clock is compared to the phase of said second clock and the frequency of said first clock is adjusted according to the result of the phase comparison; and
whereby the frequency of said first clock is based on a frame timing signal used by said network.
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7. A data communication system for transmitting data from a transmitting unit to a receiving unit via a first serial bus, an ATM (Asynchronous Transfer Mode) network, and a second serial bus, the data communication system comprising:
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first interface means for performing interface processing for said first serial bus;
second interface means for performing interface processing for said network;
third interface means for performing interface processing for said second serial bus; and
generating means for generating a first clock used by said third interface means as a cycle master clock for said second bus in synchronization with a second clock used by said second interface means as a reference clock for said ATM network, whereby said first clock is generated by a phase locked loop wherein the phase of a frequency-divided version of said first clock is compared to the phase of said second clock and the frequency of said first clock is adjusted according to the result of the phase comparison; and
whereby a reference clock of said first serial bus and said first clock are synchronized.
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8. A data communication method for transmitting data from a transmitting unit to a receiving unit via a first serial bus, an ATM (Asynchronous Transfer Mode) network, and a second serial bus, the data communication method comprising:
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a first interfacing step for performing interface processing for said first serial bus;
a second interfacing step for performing interface processing for said network;
a third interfacing step for performing interface processing for said second serial bus; and
a generating step for generating a first clock used by said third interface means as a cycle master clock for said second bus in synchronization with a second clock used by said second interface means as a reference clock for said ATM network, whereby said first clock is generated by a phase locked loop wherein the phase of a frequency-divided version of said first clock is compared to the phase of said second clock and the frequency of said first clock is adjusted according to the result of the phase comparison; and
whereby a reference clock of said first serial bus and said first clock are synchronized.
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9. A computer-readable storage medium containing a program to perform processing by a data communication method for data communication between a serial bus and an ATM (Asynchronous Transfer Mode network, the data communication method comprising:
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a first interfacing step for performing interface processing for said bus;
a second interfacing step for performing interface processing for said network; and
a generating step for generating a first clock used by said first interfacing step as a cycle master clock for said bus in synchronization with a second clock used as a reference clock for said ATM network;
whereby said first clock is generated by a phase locked loop wherein the phase of a frequency-divided version of said first clock is compared to the phase of said second clock and the frequency of said first clock is adjusted according to the result of the phase comparison.
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Specification