Chapter · Ethernet
Three routes
The classic ESP32 with an outside PHY, the ESP32-S3 over SPI, the ESP32-P4 with no Wi-Fi radio, and how to choose one and find the fault.
- 09Classic ESP32: built-in MAC, outside PHY5 minThe classic ESP32 has an Ethernet MAC inside and needs a PHY outside. Its six RMII data pins are fixed, and the 50 MHz clock comes in on GPIO0, a strapping pin that needs care at power-up.
- 10ESP32-S3: Ethernet over SPI5 minThe ESP32-S3 has no Ethernet MAC, so a whole controller hangs on its SPI bus. With a W5500 the TCP/IP stack can run on the ESP32 as lwIP or inside the chip as its own sockets, and the library decides which.
- 11ESP32-P4: built-in MAC, no Wi-Fi radio4 minThe ESP32-P4 has an Ethernet MAC inside, RMII pins chosen from short lists, a clock that can come in or go out and back, a timestamp on every frame, and no Wi-Fi radio of its own.
- 12Choose a route, find the fault5 minThree ESP32 routes to a cable compared, then the order to look in when a box does not answer. The physical link first, then the PHY and the driver, then IP, and only then the application.
Start at 09 and read down — the order is the order things get easier in. Or take the one with your part in it; every article stands on its own, and links back to whatever it needs.