Cortex-M4 Devices Generic User Guide: 4.4. System timer, SysTick

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.

Note

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

The system timer registers are:

Table 4.32. System timer registers summary

Address	Name	Type	Required privilege	Reset value	Description
`0xE000E010`	SYST_CSR	RW	Privileged	^[a]	SysTick Control and Status Register
`0xE000E014`	SYST_RVR	RW	Privileged	Unknown	SysTick Reload Value Register
`0xE000E018`	SYST_CVR	RW	Privileged	Unknown	SysTick Current Value Register
`0xE000E01C`	SYST_CALIB	RO	Privileged	`-` ^[a]	SysTick Calibration Value Register
^[a]See the register description for more information.

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