* ao_timer.c
*/
-extern volatile __data uint16_t ao_tick_count;
+#ifndef AO_TICK_TYPE
+#define AO_TICK_TYPE uint16_t
+#define AO_TICK_SIGNED int16_t
+#endif
+
+extern volatile __data AO_TICK_TYPE ao_tick_count;
/* Our timer runs at 100Hz */
#define AO_HERTZ 100