Synchronous differential signaling protocol

• US 10,305,671 B2
• Filed: 05/19/2016
• Issued: 05/28/2019
• Est. Priority Date: 05/21/2015
• Status: Active Grant

• Current Assignee: Cirrus Logic Incorporated
• Original Assignee: Cirrus Logic Incorporated
• Inventors: Kumar, Bhoodev, Ramakrishnan, Muraleedharan, Oppula, Vivek, Hoff, Thomas, Zwart, Willem
• Primary Examiner(s): Perez, James M
• Application Number:
  US15/159,760
• Publication Number:
  US 20160344536A1
• Time in Patent Office: 1,104 Days
• Field of Search: 375354-376
• CPC Class Codes: G06F 13/40 Bus structure for computer networks G06F15/163; for optical bus networks H04B10/25
• CPC Class Codes: G06F 13/4291 using a clocked protocol
• CPC Class Codes: H04L 7/0008 Synchronisation information channels, e.g. clock distribution lines
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

Synchronous, differential signaling may be performed over a communications path through a wired connection between a master device and a slave device to provide high-bandwidth and/or low-latency communications. Flexibility may be provided in the signaling protocol by providing for a configurable frame structure. Flexibility may be provided in mapping of data streams to bit slots in a frame, varying a number of downlink and uplink slots, configuring a number of turnarounds and locations of the turnarounds within a frame, configuring location and number of control word bit (CWB) slots in a frame, and/or adjusting a clock frequency of the communications link.

Claims

1. A method of communicating between a first device and a second device, comprising:

communicating, by the first device with the second device, synchronously over a differential line to transmit data in a series of frames between the first device and the second device by using the same clock signal,

wherein the step of communicating comprises;

transmitting a first frame of the series of frames with a first structure, wherein the first structure comprises a first size, and

transmitting a second frame of the series of frames with a second structure, wherein the second structure comprises a second size, and

wherein the step of communicating comprises adjusting an allocation of downlink slots and uplink slots within frames of the series of frames.

2. The method of claim 1, further comprising recovering, by the first device, a clock signal of the second device, wherein the first device comprises a slave device and the second device comprises a master device.

3. The method of claim 2, wherein the step of recovering the clock signal comprises receiving, by the first device from the second device, synchronizing bits for detecting the clock signal of the second device.

4. The method of claim 3, wherein the step of recovering the clock signal further comprises transmitting, by the first device, a predetermined pattern to the second device;

and receiving, by the first device, a predetermined acknowledgment pattern to complete initialization of the connection.

5. The method of claim 1, wherein the step of adjusting allocation comprises adjusting a number of turnarounds within the frames of the series of frames.

6. The method of claim 1, wherein the step of adjusting allocation comprises adjusting a location of turnarounds within the frames of the series of frames.

7. The method of claim 1, wherein the step of communicating comprises adjusting a position of control bits within the frames of the series of frames.

8. The method of claim 1, wherein the step of communicating comprises adjusting a frequency of the clock signal.

9. The method of claim 1, wherein the step of communicating comprises receiving, within a burst configuration frame of the series of frames, a command, wherein the command determines an organization of data within the burst configuration frame.

10. The method of claim 9, wherein the step of communicating comprises receiving a command indicating a burst configuration for the burst configuration frame, wherein the burst configuration configures the burst configuration frame for writing control data when digital data is not present.

11. The method of claim 1, wherein the step of communicating comprises receiving, within control word bits of an interrupt frame of the series of frames, an interrupt bit indicating a received interrupt.

12. The method of claim 1, further comprising detecting, by the first device, a reset command from the second device by detecting a predefined potential on the differential line.

13. An apparatus, comprising:

a first device configured to communicate synchronously with a second device over a differential communications path by transmitting data in a series of frames between the first device and the second device using a same clock signal,

wherein the first device is configured to communicate by;

transmitting a first frame of the series of frames with a first structure, wherein the first structure comprises a first size, and

transmitting a second frame of the series of frames with a second structure, wherein the second structure comprises a second size,

wherein the first device is configured to communicate by adjusting an allocation of downlink slots and uplink slots within frames of the series of frames.

14. The apparatus of claim 13, wherein the first device is configured to recover a clock signal of the second device, wherein the first device comprises a slave device and the second device comprises a master device.

15. The apparatus of claim 14, wherein the first device is configured to receiving synchronizing bits for detecting the clock signal of the second device.

16. The apparatus of claim 15, wherein the first device is configured to transmit a predetermined pattern to the second device, and to receive a predetermined acknowledgment pattern to initialize the communications path.

17. The apparatus of claim 13, wherein the first device is configured to adjust allocation by adjusting a number of turnarounds within the frames of the series of frames.

18. The apparatus of claim 13, wherein the first device is configured to adjust allocation by adjusting a location of turnarounds within the frames of the series of frames.

19. The apparatus of claim 13, wherein the first device is configured to communicate by adjusting a position of control bits within the frames of the series of frames.

20. The apparatus of claim 13, wherein the first device is configured to communicate by adjusting a frequency of the clock signal for the synchronous, differential communications path.

21. The apparatus of claim 13, wherein the first device is configured to communicate by receiving, within a burst configuration frame of the series of frames, a command, wherein the command determines an organization of data within the burst configuration frame.

22. The apparatus of claim 21, wherein the first device is configured to communicate by receiving a command indicating a burst configuration for the burst configuration frame, wherein the burst configuration configures the burst configuration frame for writing control data when digital data is not present.

23. The apparatus of claim 13, wherein the first device is configured to communicate by receiving, within control word bits of an interrupt frame of the series of frames, an interrupt bit indicating a received interrupt.

24. The apparatus of claim 13, wherein the first device is configured to communicate by detecting a reset command from the second device by detecting a predefined potential on the differential line.

25. A system, comprising:

a master device;

a slave device; and

a communications path between the master device and the slave device, wherein the master device and the slave device are configured to communicate using a series of frames transmitted in synchronous, differential signals over the communications path using a same clock signal, and

wherein the master device is configured to communicate the series of frames by;

transmitting a first frame of a series of frames with a first structure, wherein the first structure comprises a first size, and

transmitting a second frame of a series of frames with a second structure, wherein the second structure comprises a second size,

wherein the master device and the slave device are configured to communicate by adjusting an allocation of downlink slots and uplink slots within frames of the series of frames.

26. The system of claim 25, wherein the slave device is configured to recover a clock signal of the master device.

27. The system of claim 26, wherein the master device is configured to transmit synchronizing bits for initializing communications over the communications path, and wherein the slave device is configured to recover the clock signal based, at least in part, on the synchronizing bits.

28. The system of claim 27, wherein the slave device is configured to transmit a predetermined pattern to the master device, wherein the master device is configured to receive the predetermined pattern and to transmit, in response, a predetermined acknowledgement pattern to initialize communications over the communications path.

29. The system of claim 25, wherein the master device and the slave device are configured to adjust allocation by adjusting a number of turnarounds within the frames of the series of frames.

30. The system of claim 25, wherein the master device and the slave device are configured to adjust allocation by adjusting a location of turnarounds within the frames of the series of frames.

31. The system of claim 25, wherein the master device and the slave device are configured to communicate by adjusting a position of control bits within the frames of the series of frames.

32. The system of claim 25, wherein the master device and the slave device are configured to communicate by adjusting a frequency of the communications path.

33. The system of claim 25, wherein the master device and the slave device are configured to communicate by transmitting a command that determines an organization of data within a burst configuration frame of the series of frames.

34. The system of claim 33, wherein the master device and the slave device are configured to communicate by receiving a command indicating a burst configuration for the burst configuration frame of the series of frames, wherein the burst configuration configures the burst configuration frame for writing control data when digital data is not present.

35. The system of claim 25, wherein the master device is configured to communicate an interrupt by setting an interrupt bit in an interrupt frame of the series of frames.

36. The system of claim 25, wherein the master device is configured to communicate a reset command by setting a predefined potential on the communications path.