Abstract

Time synchronization plays a crucial role in modern vehicles, enabling many automotive applications. These applications include synchronizing the activation of lights like front and rear indicator, making sure audio playback from multiple speakers is correctly timed, using coordinated sensor inputs like accelerometer and microphone output to cancel road noise, synchronizing the GNSS receiver to the v2x transceiver, and simultaneously operating LiDAR and radar sensors for precise area scanning.

One method of introducing time synchronization to the aforementioned applications is to implement the open standard IEEE 802.1AS with Ethernet. IEEE 802.1AS comes from Time Sensitive Networking (TSN), or a set of standards that define a method for designing systems with “packet transport with bounded latency, low packet delay variation, and low packet loss”¹. IEEE 802.1AS is one of the TSN standards that specifies the protocol and procedures used to make sure that the synchronization requirements are met for time sensitive applications with a millisecond to nanosecond synchronization accuracy. This whitepaper gives a brief overview of the applications that require time synchronization, how IEEE 802.1AS works, and how TI Ethernet PHYs DP83TG721, DP83TC817, and DP83TC818 implement IEEE 802.1AS for precise synchronization accuracy and reduced software overhead.