1 files changed, 41 insertions, 14 deletions

diff --git a/cores/arduino/wiring_pulse.c b/cores/arduino/wiring_pulse.c
index 0d96886..4c44d1c 100644
--- a/cores/arduino/wiring_pulse.c
+++ b/cores/arduino/wiring_pulse.c
@@ -28,7 +28,10 @@
 /* Measures the length (in microseconds) of a pulse on the pin; state is HIGH
  * or LOW, the type of pulse to measure.  Works on pulses from 2-3 microseconds
  * to 3 minutes in length, but must be called at least a few dozen microseconds
- * before the start of the pulse. */
+ * before the start of the pulse.
+ *
+ * This function performs better with short pulses in noInterrupt() context
+ */
 unsigned long pulseIn(uint8_t pin, uint8_t state, unsigned long timeout)
 {
 	// cache the port and bit of the pin in order to speed up the
@@ -37,33 +40,57 @@ unsigned long pulseIn(uint8_t pin, uint8_t state, unsigned long timeout)
 	uint8_t bit = digitalPinToBitMask(pin);
 	uint8_t port = digitalPinToPort(pin);
 	uint8_t stateMask = (state ? bit : 0);
-	unsigned long width = 0; // keep initialization out of time critical area
-	
+
+	// convert the timeout from microseconds to a number of times through
+	// the initial loop; it takes approximately 16 clock cycles per iteration
+	unsigned long maxloops = microsecondsToClockCycles(timeout)/16;
+
+	unsigned long width = countPulseASM(portInputRegister(port), bit, stateMask, maxloops);
+
+	// prevent clockCyclesToMicroseconds to return bogus values if countPulseASM timed out
+	if (width)
+		return clockCyclesToMicroseconds(width * 16 + 16);
+	else
+		return 0;
+}
+
+/* Measures the length (in microseconds) of a pulse on the pin; state is HIGH
+ * or LOW, the type of pulse to measure.  Works on pulses from 2-3 microseconds
+ * to 3 minutes in length, but must be called at least a few dozen microseconds
+ * before the start of the pulse.
+ *
+ * ATTENTION:
+ * this function relies on micros() so cannot be used in noInterrupt() context
+ */
+unsigned long pulseInLong(uint8_t pin, uint8_t state, unsigned long timeout)
+{
+	// cache the port and bit of the pin in order to speed up the
+	// pulse width measuring loop and achieve finer resolution.  calling
+	// digitalRead() instead yields much coarser resolution.
+	uint8_t bit = digitalPinToBitMask(pin);
+	uint8_t port = digitalPinToPort(pin);
+	uint8_t stateMask = (state ? bit : 0);
+
 	// convert the timeout from microseconds to a number of times through
 	// the initial loop; it takes 16 clock cycles per iteration.
 	unsigned long numloops = 0;
-	unsigned long maxloops = microsecondsToClockCycles(timeout) / 16;
-	
+	unsigned long maxloops = microsecondsToClockCycles(timeout);
+
 	// 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)
 			return 0;
-	
+
+	unsigned long start = micros();
 	// wait for the pulse to stop
 	while ((*portInputRegister(port) & bit) == stateMask) {
 		if (numloops++ == maxloops)
 			return 0;
-		width++;
 	}
-
-	// convert the reading to microseconds. The loop has been determined
-	// to be 20 clock cycles long and have about 16 clocks between the edge
-	// and the start of the loop. There will be some error introduced by
-	// the interrupt handlers.
-	return clockCyclesToMicroseconds(width * 21 + 16); 
+	return micros() - start;
 }