diff --git a/clock.c b/clock.c
index 860caa0..e28d632 100644
--- a/clock.c
+++ b/clock.c
@@ -17,6 +17,46 @@
 #endif
 #include	"memory_barrier.h"
 
+
+/// Every time our clock fires we increment this,
+/// so we know when 10ms has elapsed.
+uint8_t clock_counter_10ms = 0;
+/// Keep track of when 250ms has elapsed.
+uint8_t clock_counter_250ms = 0;
+/// Keep track of when 1s has elapsed.
+uint8_t clock_counter_1s = 0;
+
+/// Flags to tell main loop when above have elapsed.
+volatile uint8_t clock_flag_10ms = 0;
+volatile uint8_t clock_flag_250ms = 0;
+volatile uint8_t clock_flag_1s = 0;
+
+
+/** Advance our clock by a tick.
+
+  Update clock counters accordingly. Should be called from the TICK_TIME
+  Interrupt in timer.c.
+*/
+void clock_tick(void) {
+  clock_counter_10ms += TICK_TIME_MS;
+  if (clock_counter_10ms >= 10) {
+    clock_counter_10ms -= 10;
+    clock_flag_10ms = 1;
+
+    clock_counter_250ms++;
+    if (clock_counter_250ms >= 25) {
+      clock_counter_250ms = 0;
+      clock_flag_250ms = 1;
+
+      clock_counter_1s++;
+      if (clock_counter_1s >= 4) {
+        clock_counter_1s = 0;
+        clock_flag_1s = 1;
+      }
+    }
+  }
+}
+
 /*!	do stuff every 1/4 second
 
 	called from clock_10ms(), do not call directly
diff --git a/clock.h b/clock.h
index c0266b8..9cd55cd 100644
--- a/clock.h
+++ b/clock.h
@@ -1,6 +1,21 @@
 #ifndef	_CLOCK_H
 #define	_CLOCK_H
 
+#include <stdint.h>
+
+
+extern volatile uint8_t clock_flag_10ms;
+extern volatile uint8_t clock_flag_250ms;
+extern volatile uint8_t clock_flag_1s;
+
+
+// If the specific bit is set, execute the following block exactly once
+// and then clear the flag.
+#define ifclock(F) for ( ; F; F = 0)
+
+// Should be called every TICK_TIME (currently 2 ms).
+void clock_tick(void);
+
 void clock(void);
 
 #endif	/* _CLOCK_H */
diff --git a/timer.c b/timer.c
index 18f061a..d0aa9ca 100644
--- a/timer.c
+++ b/timer.c
@@ -17,11 +17,13 @@
 
 #include	"arduino.h"
 #include	"config_wrapper.h"
+#include "clock.h"
 
 #ifdef	MOTHERBOARD
 #include	"dda_queue.h"
 #endif
 
+
 /// time until next step, as output compare register is too small for long step times
 uint32_t	next_step_time;
 
@@ -30,44 +32,13 @@ uint32_t	next_step_time;
 uint32_t	step_extra_time = 0;
 #endif /* ACCELERATION_TEMPORAL */
 
-/// every time our clock fires, we increment this so we know when 10ms has elapsed
-uint8_t						clock_counter_10ms = 0;
-/// keep track of when 250ms has elapsed
-uint8_t						clock_counter_250ms = 0;
-/// keep track of when 1s has elapsed
-uint8_t						clock_counter_1s = 0;
-
-/// flags to tell main loop when above have elapsed
-volatile uint8_t	clock_flag_10ms = 0;
-volatile uint8_t	clock_flag_250ms = 0;
-volatile uint8_t	clock_flag_1s = 0;
 
 /// comparator B is the system clock, happens every TICK_TIME
 ISR(TIMER1_COMPB_vect) {
 	// set output compare register to the next clock tick
 	OCR1B = (OCR1B + TICK_TIME) & 0xFFFF;
 
-	/*
-	clock stuff
-	*/
-	clock_counter_10ms += TICK_TIME_MS;
-	if (clock_counter_10ms >= 10) {
-		clock_counter_10ms -= 10;
-		clock_flag_10ms = 1;
-
-		clock_counter_250ms++;
-		if (clock_counter_250ms >= 25) {
-			clock_counter_250ms = 0;
-			clock_flag_250ms = 1;
-
-			clock_counter_1s++;
-			if (clock_counter_1s >= 4) {
-				clock_counter_1s = 0;
-				clock_flag_1s = 1;
-			}
-		}
-	}
-
+  clock_tick();
   dda_clock();
 }
 
diff --git a/timer.h b/timer.h
index 9bfd487..0154191 100644
--- a/timer.h
+++ b/timer.h
@@ -7,6 +7,7 @@
 #endif
 #include "simulator.h"
 
+
 // time-related constants
 #define	US	* (F_CPU / 1000000)
 #define	MS	* (F_CPU / 1000)
@@ -19,16 +20,6 @@
 /// properly if you change TICK_TIME.
 #define TICK_TIME_MS (TICK_TIME / (F_CPU / 1000))
 
-/*
-clock stuff
-*/
-extern volatile uint8_t	clock_flag_10ms;
-extern volatile uint8_t	clock_flag_250ms;
-extern volatile uint8_t	clock_flag_1s;
-
-// If the specific bit is set, execute the following block exactly once
-// and then clear the flag.
-#define	ifclock(F)	for (;F;F=0 )
 
 /*
 timer stuff