SNLA417 January   2023 DP83TC812R-Q1 , DP83TC812S-Q1

 

  1.   Abstract
  2. 1Introduction
    1. 1.1 Acronyms
  3. 2TC10 Test Setup
    1. 2.1 Overview
    2. 2.2 Wakeup to Linking Sequence
  4. 3Measurement Summary
    1. 3.1 Complete Timing Diagram
    2. 3.2 Measurement Summary
    3. 3.3 LP1 Wake to Linking Time
  5. 4Timing Measurements
    1. 4.1 LP1 WAKE to INH (T1)
    2. 4.2 LP1 INH to WUP (T2)
    3. 4.3 WUP to PHY INH (T3)
    4. 4.4 PHY INH/Buck EN to Buck nRESET (T4)
    5. 4.5 Buck nRESET/PMIC Enable to MCU nReset (T5)
    6. 4.6 MCU nReset to MDIO Communication (T6 and T7)
    7. 4.7 MDIO Master Configuration + Linking (T8 and T9)
  6. 5Measurement Evaluation
    1. 5.1 Recommendations for Optimizing Variable TC10 Times
      1. 5.1.1 Improving MCU Boot-up Time (T6)
      2. 5.1.2 Improving MDIO State Machine (T7)
      3. 5.1.3 Optimizing MDIO Timeline (T8)
        1. 5.1.3.1 Optimizing Master Configuration by Removing Polling
        2. 5.1.3.2 Optimizing Master Configuration by Improving MDC
      4. 5.1.4 PHY Configuration During Sleep
      5. 5.1.5 Other Configurable Values
    2. 5.2 Alternative TC10 Test
  7. 6Conclusion
  8. 7References

5.1.2 Improving MDIO State Machine (T7)

The interval tlink – tMDIO is dependent on when the PHY master configuration actually begins. Optimizing T7 allows T8 and T9 to occur sooner. Keeping T7 idling for too long only increases the PHY link time.

Reducing T7 depends on the implementation of the PHY state machine in the MCU. The PHY state machine defines the steps before and after the master configuration when the MDIO is active. As an example, Figure 5-1 shows the MDIO state machine for the AM273x-Q1 SDK.

Figure 5-1 MDIO State Machine for AM273x-Q1 SDK

Possible optimizations of this state machine include:

  • The AM273x-Q1 software development kit (SDK) contains many drivers for various PHYs. However, the AM273x-Q1 can be optimized to use the DP83TC812-Q1 driver to save time.
  • The DP83TC812-Q1 always transmits or receives data at a rate of 100Mbps. Selecting a speed of 100Mbps is not necessary.