Embedded Systems Architecture

Clock configuration

The configuration of the clocks in Cortex-M microcontrollers happens through the Reset and Clock Control (RCC) registers, located at a specific address within the internal peripheral region. The RCC configuration is vendor-specific, as it depends on the logic of the PLL implemented in the microcontroller. The registers are described in the documentation of the microcontroller, and often, example source code is provided by the chip manufacturer to demonstrate how to properly configure the clocks on the microcontroller. On our reference target, STM32F407, assuming that an external 8 MHz oscillator is used as a source, the following procedure configures a 168 MHz system clock, and ensures that the clock is also distributed ...