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

2008-11-08 21:31:12 +00:00 · 2008-11-08 21:31:12 +00:00 · 68e9d04f91
parent 80fc987a94
commit 68e9d04f91
1 changed files with 5 additions and 0 deletions
--- a/cores/arduino/wiring_pulse.c
+++ b/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)