Registers & Memory-Mapped I/O

How writing a memory address turns on an LED: control/status/data registers, the volatile register-overlay struct, and the write-1-to-clear and atomic set/reset traps.

22 min read

In this lesson:

what a hardware register is and the three kinds (control, status, data)
memory-mapped I/O: base address + offset, and the register-overlay struct
why volatile is mandatory and why width/alignment matter
atomic set/reset registers (BSRR) vs read-modify-write
write-1-to-clear flags and other "registers aren't normal memory" traps

This is the hardware view of the pointer/volatile/struct-overlay ideas from the C module.

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