linking...
.\Output\GPIOled.axf: Error: L6218E: Undefined symbol SysTick_CLKSourceConfig (referred from systick.o).
.\Output\GPIOled.axf: Error: L6218E: Undefined symbol SysTick_CounterCmd (referred from systick.o).
.\Output\GPIOled.axf: Error: L6218E: Undefined symbol SysTick_ITConfig (referred from systick.o).
.\Output\GPIOled.axf: Error: L6218E: Undefined symbol SysTick_SetReload (referred from systick.o).
Target not created