diff --git a/cores/arduino/wiring_time.h b/cores/arduino/wiring_time.h
index da9698b..9f1e690 100644
--- a/cores/arduino/wiring_time.h
+++ b/cores/arduino/wiring_time.h
@@ -24,6 +24,10 @@
 extern "C" {
 #endif
 
+#define clockCyclesPerMicrosecond()   (F_CPU / 1000000L)
+#define clockCyclesToMicroseconds(a)  ((a) / clockCyclesPerMicrosecond())
+#define microsecondsToClockCycles(a)  ((a) * clockCyclesPerMicrosecond())
+
 /**
  * \brief Initialize timer for creating delays
  *