System and methods for enabling a controller area network (CAN) device to operate in different power modes based upon the payload of a wake-up message
Systems and methods for handling wake-up messages in a Controller Area Network (CAN) are described. In some embodiments, a method may include operating a CAN controller in a selected one of a plurality of operating modes in response to the detection of an event or activity on a CAN bus. The method may also include handling, by the CAN controller, a CAN message using a message handling protocol associated with the selected one of the plurality of operating modes, for example, while a host processor operates in a low power mode. In various implementations, each of the plurality of operating modes may correspond to a different amount of power consumption by the CAN controller. The method may further include transmitting a selected one of a plurality of response messages by the CAN controller over the CAN bus, in some cases, without waking up the processor from the low power mode.
1. A method, comprising:
receiving, from a host processor coupled to a Controller Area Network (CAN) controller, an instruction for the CAN controller to operate in a selected one of a plurality of operating modes upon detection of a selected one of a plurality of wake-up messages transmitted via a CAN bus, wherein each of the plurality of operating modes consumes less power than a fully operational mode;
operating a CAN controller in a given operating mode different from the plurality of operating modes, wherein the given operating mode consumes less power than any of the plurality of operating modes;
detecting the plurality of wake-up messages on the CAN bus;
identifying the selected wake-up message among the plurality of detected wake-up messages based, at least in part, upon a comparison between information contained in a payload of the selected wake-up message and stored information accessible to the CAN controller;
in response to the identification of the selected wake-up message, operating the CAN controller in the selected one of the plurality of operating modes;
performing a CAN task while in the selected one of the plurality of operating modes, based upon the information contained in the payload of the selected wake-up message, wherein the CAN task depends upon the type of CAN node to which the host processor and CAN controller belong; and
handling, by the CAN controller, a CAN message subsequently received over the CAN bus using a message handling protocol associated with the selected one of the plurality of operating modes, at least in part, while at least one processor of the host processor operates in a low power mode.
2. The method of claim 1 , wherein each of the plurality of operating modes corresponds to a different amount of power consumption by the CAN controller.
3. The method of claim 1 , wherein the instruction to operate in the selected one of the plurality of operating modes allows the CAN controller to operate in any of a subset of the plurality of operating modes, and wherein selection of the selected operating mode among the subset of operating modes is performed by the CAN controller based upon the information contained in the payload of the selected wake-up message prior to the at least one processor core having entered the low power mode.
4. The method of claim 1 , wherein at least one portion of the CAN message includes a message identification, and wherein the stored information includes stored message identification information.
5. The method of claim 4 , wherein the message handling protocol includes a sequence of one or more logical operations to be performed in the comparison between the message identification and the stored message identification information.
6. The method of claim 1 , further comprising:
in response to the information contained in the payload of a given wake-up message not matching the stored information, operating the CAN controller in another operating mode, the other operating mode corresponding to a lesser amount of power consumption than the selected operating mode; or
in response to the information contained in the payload of the given wake-up message matching the stored information, operating the CAN controller in yet another operating mode, the yet another operating mode corresponding to a higher amount of power consumption than the selected operating mode.
7. The method of claim 1 , further comprising:
waking up the at least one processor core from the low power mode, at least in part, in response to the information contained in the payload of the selected wake-up message matching the stored information.
8. The method of claim 1 , wherein handling the CAN message includes transmitting a selected one of a plurality of response messages by the CAN controller over the CAN bus without waking up the at least one processor core from the low power mode.
9. The method of claim 1 , further comprising:
receiving, at the CAN controller, an identification of the selected one of the plurality of operating modes, the identification having been configured by the at least one processor core prior to the at least one processor core having entered the low power mode.
10. The method of claim 1 , further comprising:
receiving, at the CAN controller, an identification of allowed ones of the plurality of operating modes, the identification having been configured by the at least one processor core prior to the at least one processor core having entered the low power mode; and
identifying, by the CAN controller, the selected one of the plurality of operating modes among the allowed ones of the plurality of operating modes, at least in part, in response to contents of the CAN message.
11. A Controller Area Network (CAN) controller, comprising:
message processing circuitry configured to receive, from a host processor, an indication of a selected one of three or more operating modes, each of the three or more operating modes corresponding to a different level of power consumption and to a different CAN message handling protocol, the message processing circuitry further configured to process a given one of a plurality of CAN messages received over a CAN bus using a corresponding one of the different CAN message handling protocols, the message processing circuit further configured to identify one of the plurality of CAN messages as being relevant to the operation of the CAN controller based, at least in part, upon a comparison between information contained in a payload of the relevant CAN message and information stored in the CAN controller; and
power control circuitry operably coupled to the message processing circuitry, the power control circuitry configured to cause the CAN controller to operate in a low power mode configured to consume less power than any of the three or more operating modes, and perform the following operations in response to the message processing circuit's identification of the relevant CAN message among the plurality of CAN messages using a first CAN message handling protocol corresponding to the low power mode;(1) cause the CAN controller to operate in the selected operating mode; and (2) process the payload of the relevant CAN message and a payload of at least one subsequent CAN message using a second CAN message handling protocol corresponding to the selected operation mode, wherein the second CAN message handling protocol consumes more power than the first CAN message handling protocol.
12. The CAN controller of claim 11 , wherein the indication allows the message processing circuit to operate in any of a subset of the three or more operating modes, and wherein selection of the selected operating mode among the subset of operating modes is performed by the CAN controller based upon contents of the payload of the relevant CAN message.
13. The CAN controller of claim 11 , wherein the message processing circuitry is further configured to wake up the host processor from a sleep mode in response to a successful match between at least one portion of the payload of the relevant CAN message and the stored information.
14. The CAN controller of claim 11 , wherein the message processing circuitry is further configured to select and transmit one of a plurality of CAN response messages in response to the received CAN message and without waking up the host processor from a sleep mode.
15. The CAN controller of claim 11 , wherein the indication of the selected one of the plurality of three or more operating modes includes a selected one of the different levels of power consumption by the CAN controller, and wherein the message processing circuitry is further configured to identify the selected one of the plurality of three or more operating modes based, at least in part, upon the selected one of the different levels of power consumption.
16. A Controller Area Network (CAN) node, comprising:
a host processor including a core and a CAN controller operably coupled to the core, the CAN controller configured to receive, from the core, an identification of at least one of a plurality of operating modes to be employed by the CAN controller in response to the CAN controller's receipt of a particular CAN wake-up message transmitted among a plurality of other CAN wake-up message on a CAN bus coupled to the CAN controller, the CAN controller further configured to operate in another mode different from the at least one of the plurality of operating modes prior to receipt of the particular CAN wake-up message, the CAN controller further configured to handle CAN messages using a corresponding one of a plurality of different message handling protocols while the core operates in a low power mode, each of the plurality of operating modes corresponding to a different amount of power consumption by the CAN controller, the CAN controller further configured to identify the particular CAN wake-up message among a plurality of received CAN wake-up messages based, at least in part, upon a comparison between information contained in a payload of the particular CAN wake-up message and information stored in the CAN controller.
17. The CAN node of claim 16 , wherein the identification specifies a single one of the plurality of operating modes of the CAN controller, and wherein the identification is configured to cause the CAN controller to switch its operation from a low power mode to the single one of the plurality of operating modes to handle the CAN wake-up message using a corresponding message handling protocol.
18. The CAN node of claim 16 , wherein the identification specifies two or more of the plurality of operating modes, and wherein the identification is configured to allow the CAN controller to select one of the specified operating modes, at least in part, in response to identification information within the particular CAN wake-up message.
19. The CAN node of claim 16 , wherein the core is configured to continue operating in the low power mode during handling of the particular CAN wake-up message by the CAN controller and during transmission of a response message by the CAN controller.
20. The CAN node of claim 16 , wherein each of the plurality of different message handling protocols is configured to identify a given CAN wake-up message, at least in part, by matching a combination of CAN message ID and payload information.