Module clock 

EMAC clock configuration for ESP32-P4.

RMII reference clock sources

The ESP32-P4 EMAC needs a 50 MHz reference clock for RMII.

• ExternalRefClock — the PHY drives the reference clock into one of the EMAC_RMII_CLK input pads (GPIO32, GPIO44, or GPIO50). This is the recommended configuration when the PHY has an integrated oscillator.

• InternalRefClock — the ESP32-P4 MPLL generates a 50 MHz clock and drives it out on a REF_50M_CLK pad (GPIO23 or GPIO39). This signal must be looped back externally into one of the EMAC_RMII_CLK input pads.

MII clock source

The PHY drives TX_CLK and RX_CLK separately at 25 MHz (100 Mbps) or 2.5 MHz (10 Mbps). No internal clock generation is required.

Structs

ExternalRefClock

RMII reference clock provided externally by the PHY.

InternalRefClock

RMII reference clock derived from the ESP32-P4 MPLL at 50 MHz.