4.4. System timer, SysTick

The processor has a 24-bit system timer, SysTick, that counts down from the reload value to zero, reloads, that is wraps to, the value in the SYST_RVR register on the next clock edge, then counts down on subsequent clocks.


When the processor is halted for debugging the counter does not decrement.

The system timer registers are:

Table 4.32. System timer registers summary

AddressNameTypeRequired privilege

Reset value

0xE000E010SYST_CSRRWPrivileged[a]SysTick Control and Status Register
0xE000E014SYST_RVRRWPrivilegedUNKNOWNSysTick Reload Value Register
0xE000E018SYST_CVRRWPrivilegedUNKNOWNSysTick Current Value Register

- [a]

SysTick Calibration Value Register

[a] See the register description for more information.

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