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KV58: is RMII clock supported on ENET_1588_CLKIN

Question asked by Iain Rist on Sep 26, 2018
Latest reply on Sep 26, 2018 by Robin_Shen

I want to run my microcontroller with the system clock derived from EXTAL and the RMII clock sourced from ENET_1588_CLKIN. I cannot run with a 50 MHz clock attached to EXTAL due to system requirements.

 

The KV58 reference manual inlcludes the following contradictory statements:

  1. RMII clock source is tied to EXTAL:
    • Section 51.1.2 states that RMII_REF_CLK is internally tied to EXTAL.
  2. RMII clock source is configurable:
    • Section 6.5.9 and Table 11-26 state that the RMII clock source can be EXTAL or ENET_1588_CLKIN, selected via SIM_SOPT2[RMIISRC].

 

Which one is it? Can I have the microcontroller system clock derived from EXTAL and have the RMII clock sourced from a 50 MHz clock attached to ENET_1588_CLKIN?

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