SNLA417 January 2023 DP83TC812R-Q1 , DP83TC812S-Q1
This document describes the setup and measurements of TC10 protocol for a complete automotive Ethernet system that utilizes the DP83TC812-Q1 Ethernet Physical Layer (PHY).
In today’s automotive industry, vehicles – especially electric vehicles (EVs) – are met with the problem of excessive battery consumption from electronic systems. This issue can be mitigated through partial networking using TC10 protocol. TC10 allows Ethernet nodes and their respective electronic control units (ECU) to be disabled when not in use which leads to longer drive range and reduced battery consumption.
The Open Alliance TC10 specification is an automotive Ethernet standard which defines a sleep mode and wake-up mechanism. To learn more about the general TC10 Sleep and Wake Sequence, see the What is the TC10 automotive Ethernet standard and why is it important? video.
This document demonstrates measurements for a complete Ethernet system that utilizes the DP83TC812-Q1, a 100BASE-T1-compliant Ethernet PHY with TC10 sleep and wake functionality. When a sleeping ECU receives a TC10 wake-up pulse (WUP), the ECU must wake and establish the Ethernet link in a reasonable amount of time. Thus, the sleeping ECU can be awakened and perform the requested function with minimal delay. This application note analyzes the steps a TC10 system goes through to wake up and link the Ethernet PHYs as well as detailing any possible optimizations for faster TC10 wake-up times. For more information on the DP83TC812-Q1 PHY configuration for TC10, see the DP83TC812, DP83TC813: System Implementation of Open Alliance TC10 Sleep/Wake-up application note.
This section defines the acronyms used in this document.
MDI | Medium Dependent Interface |
MDIO | Management Data Input/Output |
MDC | Management Data Clock |
PHY | Physical Layer |
PCS | Physical Coding Sublayer |
PMA | Physical Medium Attachment |
MAC |
Medium Access Control |
A test board was used to replicate a sleeping vehicle ECU which is referred to as Link Partner 2 (LP2). LP2 includes a LM62460-Q1 buck converter, LP8762-Q1 power management integrated circuit (PMIC), AM273x-Q1 Arm® based MCU, and the DP83TC812-Q1 TC10-compliant automotive Ethernet PHY. LP2 was used in conjunction with the DP83TC812EVM-MC to establish a link between the two devices, enter sleep mode, and then perform a remote TC10 wake sequence. The DP83TC812EVM-MC is referred as Link Partner 1 (LP1). Figure 2-1 shows how these components behave as a system.
The components and steps that precede the LP1 WAKE pin going high are particularly important because these components and steps decide how fast the system is going to wake up and establish an Ethernet link to begin communication. Overall, the hardware sets a strict limit on the wake-up time. Software also impacts this time, but the time software adds to the wake-up sequence varies with software optimization.
The following steps explain the wakeup to linking sequence:
For this test, both PHYs are bootstrapped as slave; however, the AM273x-Q1 configures the PHY of LP2 to be a master so the devices only link after the AM273x-Q1 is on and ready to communicate. This action is to prevent packet loss due to both PHYs being awake and linked without the MCU being ready to receive packets. Therefore, the linking process can occur only after the AM273x-Q1 has finished the boot-up sequence and has configured the PHY as a master through MDIO communication.
Figure 3-1 illustrates the timeline of each measurement. The wake-up sequence is broken down in steps from T1 to T9. T6, T7, and T8 are marked with “*” (an asterisk) because they are dependent on software. Therefore, T6, T7, and T8 are areas where any design can look to further optimize the TC10 timing. The other time intervals are based only on the hardware of the system.