Advanced I/O
Extension Input/Output (Tone Output and Shift Input)
This library is used to generate a square wave, input/output serial data (software), and for pulse width measurement.
tone
- Description
- Generates a square wave of the specified frequency. Useful for turning on a buzzer.
- Syntax
- tone(int pin, int frequency, int duration)
- Parameters
- pin: The pin on which to generate the tone
frequency: The frequency of the tone in hertz [Hz]
duration: The duration of the tone in milliseconds
Continues to buzz when abbreviated or set to 0
- Returns
- Nothing
noTone
- Description
- Stops the generation of a square wave triggered by tone(). Has no effect if no tone is being generated.
- Syntax
- noTone(int pin)
- Parameters
- pin: The pin on which to stop generating the tone.
- Returns
- Nothing
shiftOut
- Description
- Shifts out a byte of data one bit at a time. Starts from either the most (the leftmost) or least (the rightmost) significant bit. Each bit is written in turn to a data pin, after which a clock pin is pulsed (taken high, then low) to indicate that the bit is available.
- Syntax
- shiftOut(int dataPin, int clockPin, bitOrder, unsigned char value)
- Parameters
- dataPin: The pin on which to output each bit
clockPin: The pin to toggle once the dataPin has been set to the correct value
bitOrder: Which order to shift out the bits; either MSBFIRST or LSBFIRST (Most Significant Bit First, or, Least Significant Bit First)
value: The data to shift out.(unsigned char 8-bit data)
- Returns
- Nothing
shiftIn
- Description
- Shifts in a byte of data one bit at a time. Starts from either the most (the leftmost) or least (the rightmost) significant bit. For each bit, the clock pin is pulled high, the next bit is read from the data line, and then the clock pin is taken low.
- Syntax
- unsigned char shiftIn(unsigned char dataPin, unsigned char clockPin, bitOrder)
- Parameters
- dataPin: The pin on which to input each bit
clockPin: The pin to toggle to signal a read from the dataPin
bitOrder: Which order to shift in the bits; either MSBFIRST or LSBFIRST
- Returns
- The value read (8-bit data)
pulseIn
- Description
- Reads a pulse (either HIGH or LOW) on a pin.
- Syntax
- unsigned long pulseIn(int pin, int val, unsigned long timeout = 1000000)
- Parameters
- pin: The number of the pin on which you want to read the pulse
val: Type of pulse to read: either HIGH or LOW
timeout: The number of microseconds to wait for the pulse to start; default is one second
- Returns
- The length of the pulse (in microseconds) or 0 if no pulse started before the timeout (unsigned long)
Sample Program
Sample for tone.
#include <Arduino.h> void setup(){ tone(2, 261); delay(500); tone(2, 293); delay(500); tone(2, 329); delay(500); noTone(2); delay(500); } void loop(){ }