PM0215 datasheet(85/91 Pages) STMICROELECTRONICS

85 / 91 page

PM0215

Core peripherals

Doc ID 022979 Rev 1

85/91

4.4

SysTick timer (STK)

When enabled, the timer:

●

counts down from the reload value to zero,

●

reloads (wraps to) the value in the STK_RVR on the next clock cycle,

●

then decrements on subsequent clock cycles.

Writing a value of zero to the STK_RVR disables the counter on the next wrap.

When the counter transitions to zero, the COUNTFLAG status bit is set to 1.

Reading STK_CSR clears the COUNTFLAG bit to 0.

Writing to the STK_CVR clears the register and the COUNTFLAG status bit to 0. The write

does not trigger the SysTick exception logic.

Reading the register returns its value at the time it is accessed.

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

Table 33.

System timer registers summary

Address

Name

Type

Reset value

Description

0xE000E010 STK_CSR

0x00000000

SysTick control and status register (STK_CSR)

on page 86

0xE000E014 STK_RVR

Unknown

SysTick reload value register (STK_RVR) on

page 87

0xE000E018 STK_CVR

Unknown

SysTick current value register (STK_CVR) on

page 87

0xE000E01C STK_CALIB RO

0xC0000000

SysTick calibration value register (STK_CALIB)

on page 88

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