In this article, we will talk about STM32 microcontrollers with a built-in Ethernet controller. That includes microcontrollers from F1, F2, F4, F7, H5, H7 series. We will cover both the hardware part, and the software part. For a practical application demo of these principles, see the complete tutorial, including a video that explains how STM32’s built-in Ethernet MAC connects to an external PHY using RMII, how DMA descriptors work, and how to configure CubeMX or bare-metal projects for reliable networking. You will also see a demo of building a bare-metal web dashboard. Let's start with the hardware. Ethernet hardware The first thing to understand is that the Ethernet controller, unlike other controllers, is divided into two parts: the MAC controller and the PHY controller. This separation exists because Ethernet can operate over different media - for example, a standard wired cable with eight wires, or an optical cable, or a single-pair Ethernet cable with two wires.…