SoC

Embedded platform discussions often use different words as if they meant the same thing.

“This project uses ARM.” “This chip is RISC-V.” “This core supports Linux.” “This board has an MMU.” “Interrupts are different on this architecture.” “This toolchain is incompatible.” Some of these statements are true, and some are only half true. The problem is that they often collapse ISA, CPU core, privileged architecture, SoC, board, and software platform into one layer.

Many peripheral problems do not look like clock problems at first.

UART baud rate is slightly wrong. SPI fails when the rate is raised. I2C occasionally times out. A timer period drifts. ADC sampling does not match the expected rate. The CPU runs at a high frequency, but peripheral register access is still slow. A more subtle case: everything works before sleep, but the first peripheral access after wakeup fails, or a UART works in the bootloader and then stops working once the operating system takes over.