Message buffer for a receiver apparatus on a communications bus

• US 20070230484A1
• Filed: 03/31/2006
• Published: 10/04/2007
• Est. Priority Date: 03/31/2006
• Status: Active Grant

• Current Assignee: North Star Innovations Inc. (Wi-LAN Inc.)
• Original Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Inventors: Hu, Carl, Gauen, Kim
• Granted Patent: US 7,539,888 B2
• Time in Patent Office: Days
• US Class Current: 370/401
• CPC Class Codes: H04L 12/40039 Details regarding the setting of the power status of a node according to activity on the bus
• CPC Class Codes: H04L 12/66 Arrangements for connecting between networks having differing types of switching systems, e.g. gateways
• CPC Class Codes: H04L 2012/40215 Controller Area Network CAN
• CPC Class Codes: H04L 2012/40273 the transportation system being a vehicle

Abstract

A Controller Area Network (CAN) node consists of a high-powered microcontroller, a low standby power regulator, a CAN bus transceiver, and a minimal CAN message buffer for storing received messages. Low power standby operation allows for the controller to power off, while the transceiver and regulator are operated in standby. The transceiver/regulator will enter run mode after the first symbol of a received CAN message is validated off the bus. As the original CAN message is received, it is buffered in the message buffer and, after stored, a status register is set to indicate the full message has been received. Once the controller has stabilized out of a wake-up mode, it retrieves the stored message and acts accordingly. The CAN message buffer is coupled to the controller by an system packet interface (SPI) interface for transmission of a controller wake-up command and retrieval of a buffered message.

Claims

1. A method of message buffering for a node in a multiplexed communication system, the method comprising the steps of:

receiving an incoming message over a multiplexed bus in a node of a multiplexed communication network;

sending a signal in response to the incoming message, causing a controller in the node to enter a wake-up mode of operation;

buffering the received incoming message in a memory of the node; and

transferring the buffered message to the controller after the controller has entered into its wake-up mode of operation.

2. A method of claim 1, wherein the multiplexed communication network operates in conformance with the Controller Area Network (CAN) standard.

3. A method of claim 1, further comprising the step of enabling power input to the controller in response to receiving the incoming message.

4. A method of claim 1, further comprising validating that the received incoming message indicates the incoming message is directed to the controller.

5. A method of claim 4, wherein the step of validating is performed while the controller remains in a power-off state.

6. A method of claim 1, further comprising the step of setting a status register indicating the complete incoming message has been buffered.

7. A method of claim 1, wherein the buffered message is transferred to the controller in response to a retrieval request from the controller.

8. A method of claim 1, wherein the buffered message is transferred to the controller after the controller has completed its wake-up mode of operation.

9. A method of claim 1, wherein signals sent to the controller are in accordance with a system packet interface (SPI) interface protocol.

10. A system within a node of a multiplexed communication system, wherein the node includes a controller for communication over a multiplexed bus, the system comprising:

a transceiver coupled to a bus configured for receiving and transmitting messages over the bus;

a message buffer for storing one or more messages received by the transceiver;

a power interface that generates a power control signal suitable for coupling to a controller, wherein the controller enters a power-on state in response to the power control signal; and

a controller interface suitable for coupling to a communication bus coupled to the controller providing communication between the message buffer and the controller, wherein the controller interface is configured to transfer a message stored in the message buffer to the controller.

11. The system of claim 10, wherein the multiplexed communication system is a Controller Area Network (CAN).

12. The system of claim 10, wherein power control signal is a power supply voltage.

13. The system of claim 10, wherein the controller operates in a power-off mode prior to receiving the power control signal.

14. The system of claim 10, further comprising a symbol decoder for decoding a received message.

15. The system of claim 10, further comprising message validation logic for validating that a received message is intended for the controller.

16. The system of claim 10, further comprising a power supply regulator coupled to the power interface for receiving the power control signal, wherein the power supply regulator enters into a power-on state in response to the power control signal to provide the controller coupled thereto with sufficient power for power-on operation.

17. The system of claim 10, wherein the controller interface is configured to send, in response to validating a received message for the controller, a request via the controller interface that the controller wake-up.

18. The system of claim 10, further wherein the controller interface is configured to transfer a message stored in the message buffer to the controller in response to an indication that the controller has completed a wake-up mode of operation.

19. The system of claim 10, wherein the controller interface is further configured to set a status register when the message buffer has completed storing a received message, and wherein the register is configured to allow the controller to read the status register and retrieve a buffered message in response to the setting of the status register.

20. The system of claim 10, wherein the controller interface is a SPI bus.