-//! The system timer for events is currently TMRA0. We prefer A/B over C/D because
-// A/B share the pin with the quadrature decoder module, and we do not need
-// pins for our system timer.
-// If you want to change this setting, you need also to modify the IRQ vector table.
-#define REG_SYSTEM_TIMER (REG_TIMER_A + 0)
-#define SYSTEM_TIMER_IRQ_VECTOR 42 /* TMRA0 */
+// Calculate register pointer and irq vector from hw.h setting
+#define REG_SYSTEM_TIMER PP_CAT(REG_TIMER_, SYSTEM_TIMER)
+#define SYSTEM_TIMER_IRQ_VECTOR PP_CAT(IRQ_TIMER_, SYSTEM_TIMER)