The Anatomy of a Peripheral
An STM32F411RE has a UART, three SPIs, three I²C controllers, eight timers, an ADC, a USB controller, an RTC, two watchdogs and two DMA engines. The reference manual gives each of them thirty to eighty pages, and read front to back they look like thirteen unrelated pieces of hardware. They are not. They are thirteen instances of one design, drawn by the same team, wired onto the same two buses, and configured by the same six steps in the same order every time.