Systick Reload Value Register (Stk_Rvr); Systick Current Value Register (Stk_Cvr) - ST STM32F0 Series Programming Manual

PM0215
4.4.2

SysTick reload value register (STK_RVR)

Address offset: 0x04
Reset value: Unknown
The STK_RVR specifies the start value to load into the STK_CVR.
31 30 29 28
15 14 13 12
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Bits 31:24 Reserved, must be kept cleared.
Bits 23:0 RELOAD: RELOAD value
Value to load into the STK_CVR when the counter is enabled and when it reaches 0.
Calculating the RELOAD value
The RELOAD value can be any value in the range 0x00000001-0x00FFFFFF. A start value of
0 is possible, but has no effect because the SysTick exception request and COUNTFLAG are
activated when counting from 1 to 0. To generate a multi-shot timer with a period of N
processor clock cycles, use a RELOAD value of N-1. For example, if the SysTick interrupt is
required every 100 clock pulses, set RELOAD to 99.
4.4.3

SysTick current value register (STK_CVR)

Address offset: 0x08
Reset value: Unknown
The STK_CVR contains the current value of the SysTick counter.
31 30 29 28
15 14 13 12
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Bits 31:24 Reserved, must be kept cleared.
Bits 23:0 CURRENT: Current counter value
27 26 25
Reserved
11 10 9
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27 26 25
Reserved
11 10 9
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Reads return the current value of the SysTick counter.
A write of any value clears the field to 0, and also clears the COUNTFLAG bit in the
STK_CSR register to 0.
Doc ID 022979 Rev 1
24 23 22 21
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8 7 6 5
RELOAD[15:0]
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24 23 22 21
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8 7 6 5
CURRENT[15:0]
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Core peripherals
20 19 18
RELOAD[23:16]
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4 3 2
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20 19 18
CURRENT[23:16]
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4 3 2
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17 16
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1 0
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17 16
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1 0
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