Direct data transfer between slave devices

• US 7,809,873 B2
• Filed: 04/11/2008
• Issued: 10/05/2010
• Est. Priority Date: 04/11/2008
• Status: Expired

• Current Assignee: Western Digital Israel Limited (Western Digital Corporation)
• Original Assignee: SanDisk IL Ltd. (Western Digital Corporation)
• Inventors: Perry, Nir, Pikman, Yaron
• Primary Examiner(s): Myers; Paul R
• Application Number:
  US12/101,821
• Publication Number:
  US 20090259785A1
• Time in Patent Office: 907 Days
• Field of Search: 710/110, 710/305, 711/112, 711/162
• US Class Current: 710/110
• CPC Class Codes: G06F 13/1684 using multiple buses
• CPC Class Codes: G06F 13/28 using burst mode transfer, e.g. direct memory access DMA, cycle steal G06F13/32 takes precedence

Abstract

In one aspect, a method of transferring data over a plurality of communication lines is described. A first command is sent from a master device coupled with the communication lines to a first destination slave device coupled with the communication lines instructing the first destination slave device to listen to and write data from the communication lines starting at a first time. A second command is sent from the master device to a second source slave device coupled with the communication lines instructing the second source slave device to read and output first data onto the communication lines starting at or after the first time. In this way, the first data output from the second source slave device beginning at the first time is stored by the first destination slave device beginning at the first time without requiring first transferring the data to the master device or any other device.

Claims

1. A method of transferring data between a first and a second device coupled with each other and with a master device with one or more communication lines, comprising:

instructing the first device, by the master device, to listen to the one or more communication lines until a duration D2 of time has elapsed; and

instructing the second device to continue transmitting data onto the one or more communication lines until such point as at least a duration D1 of time has elapsed, wherein the data transmitted onto the one or more communication lines by the second device is received by, the first device, without further intervention by the master device, wherein the master device determines the duration D1 based upon an amount of data to be transferred between the first and second devices and an operating frequency of the one or more communication lines, and wherein the duration D2 is at least as long as the duration D1.

2. A method as recited in claim 1, further comprising:

dividing the duration D2 of time into a plurality of time slots, wherein any data on the one or more communication lines is received by and stored at the first device only during the plurality of time slots.

3. The method as recited in claim 2, further comprising:

dividing the duration D1 of time into a plurality of time slots, wherein the second device transmits data onto the one or more communication lines only during the plurality of time slots.

4. A method as recited in claim 1, wherein the master device, first device and second device communicate according to the Secured Digital (SD) protocol.

5. A method of transferring data over a plurality of communication lines, comprising:

sending a first command from a master device coupled with the communication lines to a first destination slave device coupled with the communication lines, the first command instructing the first destination slave device to listen to and write data from the communication lines starting at a first time; and

sending a second command from the master device to a second source slave device coupled with the communication lines, the second command instructing the second source slave device to read and output first data onto the communication lines starting after the first time;

wherein the first data output from the second source slave device beginning after the first time is stored by the first destination slave device beginning after the first time without requiring first transferring the first data to the master device or any other storage device.

6. A method as recited in claim 5, wherein the master device is a host device and wherein the first and second slave devices are local storage devices.

7. A method as recited in claim 5, wherein at least one of the first and second slave devices is a removable device configured for ready removal from and addition to various communication lines.

8. A method as recited in claim 5, wherein the communication lines form a shared bus.

9. A method as recited in claim 5, wherein the first and second slave devices are two of a plurality of addressable devices arranged in a daisy chain configuration such that each of the addressable devices is connected with at least one neighboring device via one or more of the communication lines, wherein each device is connected with no more than two immediately adjacent neighboring devices, and wherein each device other than the last device in the chain passes communications, including commands, that are not targeted to itself to the next device in the chain via the communication lines that connect neighboring devices with one another.

10. A method as recited in claim 5 wherein the master device, first slave device and second slave device communicate according to the Secured Digital (SD) protocol.

11. A method as recited in claim 5, wherein the first slave device is unaware that the first data is coming directly from the second slave device and not from the master device.

12. A method as recited in claim 5, wherein the first command instructs the first device to listen to and write data from the communication lines for a first prescribed duration beginning after the first time.

13. A method as recited in claim 5, wherein the second command instructs the second slave device to output data onto the communication lines for a second prescribed duration beginning after the first time.

14. A method as recited in claim 5, further comprising sending a third command from the master device to the second slave device that instructs the second slave device to stop outputting data onto the communication lines at a second time.

15. A method as recited in claim 14, further comprising sending a fourth command from the master device to the first slave device that instructs the first slave device to stop listening to the communication lines at or after the second time.

16. A method as recited in claim 5, wherein the first command is multicast or broadcast to multiple slave devices including the first slave device substantially simultaneously and wherein the first command instructs at least a plurality of the multiple slave devices to listen to and write data from the communication lines starting at the first time such that the first data can be stored by the plurality of the multiple slave devices substantially simultaneously.

17. A method of communicating over a plurality of communication lines, comprising:

sending a first command from a master device coupled with the communication lines to a first slave device coupled with the communication lines, the first command instructing the first slave device to listen to the communication lines starting at a first time; and

sending a second command from the master device to a second slave device coupled with the communication lines, the second command instructing the second slave device to output a third communication onto the communication lines starting after the first time;

wherein the third communication output from the second slave device is read by the first slave device beginning substantially at the second time without requiring first transferring the third communication to the master device or any other device.

18. A method as recited in claim 17, wherein the at least one of the first and second slave devices is a network device.

19. A method as recited in claim 18, wherein the network device serves a network bridge between the bus and a remote network.

20. A method as recited in claim 19, wherein the first slave device is a network card, the method further comprising outputting a fourth communication onto the remote network in response to the third communication.

21. A method as recited in claim 19, wherein the second slave device is a network card and wherein the third communication includes data received from the remote network by the second slave device.

22. A system, comprising:

a first addressable destination slave device configured to store data;

a second addressable source slave device configured to store data and including first data stored therein;

a master device arranged to manage the first and second slave devices; and

a plurality of communication lines that couple the master device and at least each of the first and second slave devices; and

wherein the master device is further arranged to send a first command to the first slave device instructing the first slave device to listen to and write data from the communication lines only until a duration D2 of time has elapsed beginning at a first time and a second command to the second slave device instructing the second slave device to read and output the first data onto the communication lines beginning at or after the first time only until a duration D1 of time has elapsed, such that the first data is transferred from the second source slave device to the first destination slave device without requiring first transferring the first data to the master device or any other storage device, wherein the master device determines the duration D1 based upon an amount of data to be transferred between the first and second devices and an operating frequency of the plurality of communication lines, and wherein the duration D2 is at least as long as the duration D1.

23. A system as recited in claim 22, further comprising:

dividing the duration D2 of time into a plurality of time slots, wherein any data on the plurality of communication lines is received by and stored at the first slave device only during the plurality of time slots.

24. A system as recited in claim 22, wherein at least one of the first and second slave devices is a removable device configured for ready removal from and addition to various communication lines.

25. A system as recited in claim 22, wherein the communication lines form a shared bus.

26. A system as recited in claim 22, wherein the first and second slave devices are two of a plurality of addressable devices arranged in a daisy chain configuration such that each of the addressable devices is connected with at least one neighboring device via one or more of the communication lines, wherein each device is connected with no more than two immediately adjacent neighboring devices, and wherein each device other than the last device in the chain passes communications, including commands, that are not targeted to itself to the next device in the chain via the communication lines that connect neighboring devices with one another.

27. A system as recited in claim 22, wherein the master device, first slave device and second slave device communicate according to the Secured Digital (SD) protocol.

28. A system as recited in claim 22, wherein the first slave device is unaware that the first data is coming directly from the second slave device and not from the master device.

29. A system as recited in claim 22, wherein the first command instructs the first device to listen to and write data from the communication lines for a first prescribed duration beginning at the first time.

30. A system as recited in claim 22, wherein the second command instructs the second slave device to read and output data onto the communication lines for a second prescribed duration beginning at or after the first time.

31. A system as recited in claim 22, wherein the master device is further arranged to send a third command to the second slave device that instructs the second slave device to stop outputting data onto the communication lines at a second time.

32. A system as recited in claim 31, wherein the master device is further arranged to send a fourth command to the first slave device that instructs the first slave device to stop listening to the communication lines at or after the second time.

33. A system as recited in claim 22, wherein the first command is multicast or broadcast to multiple slave devices including the first slave device substantially simultaneously and wherein the first command instructs at least a plurality of the multiple slave devices to listen to and write data from the communication lines starting at the first time such that the first data can be stored by the plurality of the multiple slave devices substantially simultaneously.

34. The method as recited in claim 22, further comprising:

dividing the duration D1 of time into a plurality of time slots, wherein the second slave device transmits data onto the plurality of communication lines only during the plurality of time slots.