Full-duplex communication link using TDM
An automotive communication system includes multiple communication devices and a processor. The communication devices are configured to be installed in a vehicle and to communicate with one another over point-to-point Ethernet links. In each Ethernet link, a first communication device serves as a link master that is configured to set a clock signal for the link, and a second communication device serves as a slave that is configured to synchronize to the clock signal set by the first communication device. The communication devices are configured to receive data from sensors and to transmit the data over the Ethernet links. The processor is configured to receive the data from the communication devices over the Ethernet links, to synchronize the data originating from the multiple sensors to a common time-base based on link-specific clock-signal synchronization achieved on each of the links by each link master, and to process the synchronized data.
1. An automotive communication link, comprising:
a first communication device configured to serve as a master device of the automotive communication link; and
a second communication device configured to serve as a slave device of the automotive communication link,
wherein the first communication device and the second communication device are configured to be installed in a vehicle and to communicate with one another over a full-duplex point-to-point Ethernet link in a time-division multiplexing (TDM) protocol comprising unidirectional master-to-slave transmission periods and unidirectional slave-to-master transmission periods that are separate from the master-to-slave transmission periods, the slave device being configured to:
during the master-to-slave transmission periods, lock a local oscillator of the slave device on a clock signal generated by the master device; and
during the slave-to-master transmission periods, transmit data using the local oscillator that was locked on the clock signal of the master device during the master-to-slave transmission periods.
2. The automotive communication link according to claim 1 , wherein the first communication device and the second communication device are configured to perform Ethernet physical-layer (PHY) functions.
3. The automotive communication link according to claim 1 , wherein the full-duplex point-to-point Ethernet link is a single twisted-pair link.
4. The automotive communication link according to claim 1 , wherein a ratio between durations of the master-to-slave transmission periods and durations of the slave-to-master transmission periods is different from 0.5.
5. The automotive communication link according to claim 1 , wherein a ratio between durations of the master-to-slave transmission periods and durations of the slave-to-master transmission periods is greater than 0.75.
6. The automotive communication link according to claim 1 , wherein a ratio between durations of the master-to-slave transmission periods and durations of the slave-to-master transmission periods is configurable.
7. A method for communication on an automotive communication link, the method comprising:
operating a first communication device, in a vehicle, as a master device of the automotive communication link;
operating a second communication device, in the vehicle, as a slave device of the automotive communication link;
communicating between the first communication device and the second communication device over a full-duplex point-to-point Ethernet link in a time-division multiplexing (TDM) protocol comprising unidirectional master-to-slave transmission periods and unidirectional slave-to-master transmission periods that are separate from the master-to-slave transmission periods; and
in the slave device:
during the master-to-slave transmission periods, locking a local oscillator of the slave device on a clock signal generated by the master device; and
during the slave-to-master transmission periods, transmitting data using the local oscillator that was locked on the clock signal of the master device during the master-to-slave transmission periods.
8. The method for communication according to claim 7 , wherein operating the first communication device and the second communication device comprises performing Ethernet physical-layer (PHY) functions.
9. The method for communication according to claim 7 , wherein communicating over the full-duplex point-to-point Ethernet link comprises communicating over a single twisted-pair link.
10. The method for communication according to claim 7 , wherein a ratio between durations of the master-to-slave transmission periods and durations of the slave-to-master transmission periods is different from 0.5.
11. The method for communication according to claim 7 , wherein a ratio between durations of the master-to-slave transmission periods and durations of the slave-to-master transmission periods is greater than 0.75.
12. The method for communication according to claim 7 , wherein a ratio between durations of the master-to-slave transmission periods and durations of the slave-to-master transmission periods is configurable.