Datasheet

SAM4E [DATASHEET]
Atmel-11157D-ATARM-SAM4E16-SAM4E8-Datasheet_12-Jun-14
260
12.10.1.1 SysTick Control and Status
Name: SYST_CSR
Access: Read/Write
Reset: 0x000000000
The SysTick SYST_CSR enables the SysTick features.
 COUNTFLAG: Count Flag
Returns 1 if the timer counted to 0 since the last time this was read.
 CLKSOURCE: Clock Source
Indicates the clock source:
0: External Clock.
1: Processor Clock.
 TICKINT: SysTick Exception Request Enable
Enables a SysTick exception request:
0: Counting down to zero does not assert the SysTick exception request.
1: Counting down to zero asserts the SysTick exception request.
The software can use COUNTFLAG to determine if SysTick has ever counted to zero.
 ENABLE: Counter Enable
Enables the counter:
0: Counter disabled.
1: Counter enabled.
When ENABLE is set to 1, the counter loads the RELOAD value from the SYST_RVR and then counts down. On reaching
0, it sets the COUNTFLAG to 1 and optionally asserts the SysTick depending on the value of TICKINT. It then loads the
RELOAD value again, and begins counting.
31 30 29 28 27 26 25 24
–
23 22 21 20 19 18 17 16
– COUNTFLAG
15 14 13 12 11 10 9 8
–
76543210
CLKSOURCE TICKINT ENABLE