TICKINT=value1, ENABLE=value1, CLKSOURCE=value1
SysTick Control and Status Register
| ENABLE | Enable 0 (value1): counter disabled 1 (value2): counter enabled. |
| TICKINT | Tick Interrupt Enable 0 (value1): counting down to zero does not assert the SysTick exception request 1 (value2): counting down to zero to asserts the SysTick exception request. |
| CLKSOURCE | Indicates the clock source: 0 (value1): external clock 1 (value2): processor clock. |
| COUNTFLAG | Counter Flag |