Controller area network (CAN) device and method for controlling CAN traffic
Embodiments of a device and method are disclosed. In an embodiment, a CAN device is disclosed. The CAN device includes a TXD input interface, a TXD output interface, an RXD input interface, an RXD output interface, and a traffic control system connected between the TXD input and output interfaces and between the RXD input and output interfaces. The traffic control system is configured to detect the presence of CAN Flexible Data-rate (FD) traffic on the RXD input interface and if the traffic control system detects the presence of CAN FD traffic on the RXD input interface, disconnect the RXD input interface from the RXD output interface and disconnect the TXD input interface from the TXD output interface.
1. A Controller Area Network (CAN) device comprising:
a transmit data (TXD) input interface;
a TXD output interface;
a receive data (RXD) input interface;
an RXD output interface;
a traffic control system connected between the TXD input and output interfaces and between the RXD input and output interfaces, and configured to:
detect the presence of CAN Flexible Data-rate (FD) traffic on the RXD input interface; and
if the traffic control system detects the presence of CAN FD traffic on the RXD input interface, disconnect the RXD input interface from the RXD output interface and disconnect the TXD input interface from the TXD output interface and output a dominant RXD on the RXD output interface.
2. The CAN device of claim 1 , wherein the traffic control system is further configured to output a recessive TXD on the TXD output interface when the TXD input interface is disconnected from the TXD output interface.
3. The CAN device of claim 1 , wherein the traffic control system is further configured to: output a dominant RXD on the RXD output interface when the RXD input interface is disconnected from the RXD output interface; and output a recessive TXD on the TXD output interface when the TXD input interface is disconnected from the TXD output interface.
4. The CAN device of claim 1 , wherein the traffic control system is further configured to reconnect the RXD input interface to the RXD output interface and reconnect the TXD input interface from the TXD output interface after detecting the end of a CAN FD mode frame.
5. The CAN device of claim 4 , wherein the traffic control system delays reconnecting the RXD input interface to the RXD output interface and delays reconnecting the TXD input interface to the TXD output interface as long as the TXD at the TXD input interface is dominant.
6. The CAN device of claim 1 , wherein the traffic control system is further configured to reconnect the RXD input interface to the RXD output interface and reconnect the TXD input interface from the TXD output interface after detecting six consecutive equal bits on the RXD input interface.
7. The CAN device of claim 1 , wherein the traffic control system comprises a CAN protocol controller configured to decode CAN FD traffic received on the RXD input interface.
8. The CAN device of claim 1 , wherein the traffic control system further comprises a transmit path multiplexer configured to direct traffic from the TXD input interface to the TXD output interface depending on whether or not CAN FD traffic is detected.
9. The CAN device of claim 1 , wherein the traffic control system further comprises a receive path multiplexer configured to direct traffic from the RXD input interface to the RXD output interface depending on whether or not CAN FD traffic is detected.
10. A CAN transceiver device comprising a transmitter, a receiver, and a CAN bus interface, the CAN transceiver further comprising the CAN device of claim 1 .
11. A method for controlling Controller Area Network (CAN) traffic, the method comprising:
decoding traffic received on an receive data (RXD) input interface;
monitoring the decoded traffic for the presence of CAN Flexible Data-rate (FD) traffic; and
if the presence of CAN FD traffic is detected on the RXD input interface, then disconnecting the RXD input interface from an RXD output interface and disconnecting a transmit data (TXD) input interface from a TXD output interface and outputting a dominant RXD on the RXD output interface.
12. The method of claim 11 , further comprising outputting a recessive TXD on the TXD output interface when the TXD input interface is disconnected from the TXD output interface.
13. The method of claim 11 , further comprising: outputting a dominant RXD on the RXD output interface when the RXD input interface is disconnected from the RXD output interface; and outputting a recessive TXD on the TXD output interface when the TXD input interface is disconnected from the TXD output interface.
14. The method of claim 13 , further comprising reconnecting the RXD input interface to the RXD output interface and reconnecting the TXD input interface to the TXD output interface after detecting the end of a CAN FD mode frame.
15. The method of claim 14 , further comprising delaying reconnecting the RXD input interface to the RXD output interface and delaying reconnecting the TXD input interface to the TXD output interface as long as the TXD at the TXD input interface is dominant.
16. The method of claim 13 , further comprising reconnecting the RXD input interface to the RXD output interface and reconnecting the TXD input interface to the TXD output interface after detecting six consecutive equal bits on the RXD input interface.