COMBINED FLOW AND LOW-POWER STATE CONTROL USING SAME LINES BETWEEN INTERFACES

• US 20150131497A1
• Filed: 11/03/2014
• Published: 05/14/2015
• Est. Priority Date: 11/13/2013
• Status: Active Grant

• Current Assignee: STMicroelectronics International N.V. (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SAS (STMicroelectronics NV)
• Inventors: ARNAL, Christophe, VAN DER TUIJN, Roland
• Granted Patent: US 9,813,221 B2
• Time in Patent Office: Days
• US Class Current: 370/282
• CPC Class Codes: G06F 13/4291 using a clocked protocol
• CPC Class Codes: H04L 47/35 by embedding flow control information in regular packets, e.g. piggybacking
• CPC Class Codes: H04L 5/1415 using control lines
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A method for controlling a low-power state of a pair of serial interfaces using a pair of flow-control signal lines may include enabling a first of the flow-control lines by a first one of the interfaces for signaling a transmission request to the second interface. The method may also include, in response to the transmission request, waking up to a live state from a low-power state and enabling a second flow-control line for signaling a transmission authorization to the first interface. In response to the transmission authorization, the method may include initiating a transmission of a message to the second interface, and upon reaching an offset before the end of the message transmission, disabling the first flow-control line by the first interface. The method may also include, at the end of the message transmission, disabling the second flow-control line and going back into the low-power state.

Claims

1-10. -10. (canceled)

11. A method for controlling a low-power state of a pair of serial interfaces using a pair of flow-control signal lines, the method comprising:

enabling a first one of the pair of flow-control lines by a first one of the pair of serial interfaces for signalling a transmission request to a second one of the pair of serial interfaces;

in response to the transmission request, waking up to a live state from a low-power state;

enabling a second one of the pair of flow-control signal lines by the second one of the pair of serial interfaces for signalling a transmission authorization to the first one of the pair of serial interfaces;

in response to the transmission authorization, initiating a transmission of a message to the second one of the pair of serial interfaces;

upon reaching an offset before an end of the transmission of the message, disabling the first one of the pair of flow-control signal lines by the first one of the pair of serial interfaces; and

at the end of the transmission of the message, disabling the second one of the pair of flow-control signal lines by the second interface and going back into the low-power state.

12. The method of claim 11, further comprising:

providing an end-of-transmission flag in a header of each message of a sequence of the messages;

setting the end-of-transmission flag in a last message of the sequence of messages; and

disabling the second one of the pair of flow-control signal lines at an end of the last message of the sequence of messages.

13. The method of claim 11, further comprising:

transmitting a second message from the second one of the pair of serial interfaces to the first one of the pair of serial interfaces;

after disabling the second one of the pair of flow-control signal lines by the second one of the pair of serial interfaces during transmission of the second message

suspending transmission of the second message,

disabling the second one of the pair of flow-control signal lines, and

enabling the second one of the pair of flow-control signal lines again for signaling a transmission request to the first one of the pair of serial interfaces;

enabling the first one of the pair of flow-control signal lines for signaling a transmission authorization to the second one of the pair of serial interfaces; and

in response to the transmission authorization, continuing transmission of the second message.

14. The method of claim 11, further comprising:

conveying a message length in a header of the message; and

identifying the end of the transmission of the message by comparing a received data count to the message length.

15. The method of claim 11, wherein the offset is equal to an atomic data unit whose transmission is not suspended by a flow-control signal.

16. A method for controlling a low-power state of a receiver serial interface, the method comprising:

waking-up from the low-power state when a flow-control input of the receiver serial interface is enabled;

receiving a message on a serial data input of the receiver serial interface; and

returning to the low-power state at an end of the message.

17. A method for controlling a low-power state of a transmitter serial interface, the method comprising:

transmitting a message on a serial data output;

disabling a flow-control output before an end of the message; and

going into the low-power state when a flow-control input is disabled.

18. A serial interface comprising:

a serial data input;

a flow-control input; and

circuitry configured to

set the serial interface in a low-power state at an end of a message received on the serial data input, and

wake-up the serial interface to a live state from the low-power state when the flow-control input is enabled.

19. The serial interface of claim 18, wherein the circuitry is further configured to retrieve a message length conveyed in a header of the message received on the serial data input, and identify the end of the message by comparing a received data count to the message length.

20. A serial interface comprising:

a serial data output;

a flow-control output;

a flow-control input; and

circuitry configured to

transmit a message on the serial data output,

disable the flow-control output before an end of the message, and

set the serial interface in a low-power state when the flow-control input is disabled.