CLKSOURCE=VALUE_0, TICKINT=VALUE_0, ENABLE=VALUE_0
SysTick Control and Status Register
| ENABLE | SysTick Counter Enable 0 (VALUE_0): Counter disabled 1 (VALUE_1): Counter enabled |
| TICKINT | SysTick Exception Request Enable 0 (VALUE_0): Counting down to 0 does not assert the SysTick exception request 1 (VALUE_1): Counting down to 0 asserts the SysTick exception request |
| CLKSOURCE | Clock Source 0=external, 1=processor 0 (VALUE_0): External clock 1 (VALUE_1): Processor clock |
| COUNTFLAG | Timer counted to 0 since last read of register |