Waiting for pulse to start (rising or falling edge) to start timing.

arduino · Nov 8, 2008 · e79b319 · e79b319
1 parent 542a64f
commit e79b319
Showing 1 changed file with 5 additions and 0 deletions.
diff --git a/hardware/cores/arduino/wiring_pulse.c b/hardware/cores/arduino/wiring_pulse.c
@@ -44,6 +44,11 @@ unsigned long pulseIn(uint8_t pin, uint8_t state, unsigned long timeout)
 	unsigned long numloops = 0;
 	unsigned long maxloops = microsecondsToClockCycles(timeout) / 16;
 
+	// wait for any previous pulse to end
+	while ((*portInputRegister(port) & bit) == stateMask)
+		if (numloops++ == maxloops)
+			return 0;
+
 	// wait for the pulse to start
 	while ((*portInputRegister(port) & bit) != stateMask)
 		if (numloops++ == maxloops)