wiring_pulse.cpp File Reference

Pulse width measurement: pulseIn() and pulseInLong(). More...

#include "Arduino.h"

Functions
unsigned long	pulseIn (pin_size_t pin, uint8_t state, unsigned long timeout)
	Measures the length (in microseconds) of a pulse on the pin.
unsigned long	pulseInLong (pin_size_t pin, uint8_t state, unsigned long timeout)
	Measures the length (in microseconds) of a pulse on the pin.

Detailed Description

Pulse width measurement: pulseIn() and pulseInLong().

Function Documentation

pulseIn()

unsigned long pulseIn	(	pin_size_t	pin,
		uint8_t	state,
		unsigned long	timeout
	)

Measures the length (in microseconds) of a pulse on the pin.

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.

Note

This function relies on micros() so cannot be used in noInterrupt() context.

Parameters

pin	Pin number, Dx or x.
state	HIGH or LOW, the type of pulse to measure.
timeout	Maximum time to wait for the whole measure (end of any previous pulse, start and end of the pulse), in microseconds. Defaults to 1 second when omitted in C++.

Returns

Length of the pulse in microseconds, or 0 if the pulse was not completed before the timeout.

pulseInLong()

unsigned long pulseInLong	(	pin_size_t	pin,
		uint8_t	state,
		unsigned long	timeout
	)

Measures the length (in microseconds) of a pulse on the pin.

Same as pulseIn(); provided for compatibility with the AVR core.

Note

This function relies on micros() so cannot be used in noInterrupt() context.

Parameters

pin	Pin number, Dx or x.
state	HIGH or LOW, the type of pulse to measure.
timeout	Maximum time to wait for the whole measure (end of any previous pulse, start and end of the pulse), in microseconds. Defaults to 1 second when omitted in C++.

Returns

Length of the pulse in microseconds, or 0 if the pulse was not completed before the timeout.