: True Gigabit Ethernet is implemented via the Broadcom BCM54213PE PHY, which connects directly to the SoC’s RGMII interface. The 40-Pin GPIO Header
For a complete visual inspection of the circuit paths, you can download the following official and community-sourced documents: Raspberry Pi 4 Model B Full Schematic
Every HAT (Hardware Attached on Top) that connects to the GPIO header must respect the electrical characteristics and I²C/SPI/UART assignments shown in the schematic. The official references the same schematic to ensure 3.3 V logic levels and proper power sequencing. : True Gigabit Ethernet is implemented via the
Because the reduced schematic shows how the VL805 and LAN7515 are connected to the BCM2711, developers writing (e.g., for custom kernels or real‑time operating systems) can correctly initialise the PCIe and USB subsystems. developers writing (e.g.