Once a stable CPU frequency has been set up, we can configure the main timer on the system, the SysTick. Since the implementation of a specific system timer is not mandatory on all Cortex-M, sometimes it is necessary to use an ordinary auxiliary timer to keep track of the system time. In most cases, though, the SysTick interrupt can be enabled by accessing its configuration, which is located in the system control block within the system configuration region. In all Cortex-M microcontrollers that include a system tick, the configuration can be found starting at address 0xE000E010, and exposes four registers:
- The control/status register (SYSTICK_CSR) at offset 0
- The reload value register (SYSTICK_RVR) at offset 4
- The current ...