Arduino Pin Library

An easy to use Arduino library for fast and simultaneous operations on Arduino I/O pins. Supports Arduino AVR boards natively and custom boards by manually defining register addresses. Complete documentation can be found here. Source code can be found here.

• Background
• Advantages
• Benchmarks
• Usage
  • Install
  • Import Pin Library
  • Create Pin Object
  • Use as Input
  • Use as Output
  • Get Pin Info
  • Toggle
  • PWM
  • RC Timer
  • Simultaneous Operations on Multiple Pins

Background

Background information about how direct port manipulation works can be found here.

Advantages

• Much faster than built in digital functions
• Easier to read than direct port manipulation
• Allows for simultaneous operations on multiple pins
• Portable across all Arduino AVR boards
• Supports custom boards (Pin.getAnalogValue() and Pin.setDutyCycle(int value) not supported)

Benchmarks

Simple benchmark programs were created to compare this library to both the built in Arduino functions and direct port manipulation. The three benchmark programs are included in the examples/Benchmarks directory. Each program switches pin 13 between HIGH and LOW as quickly as possible. The program flash memory usage and the frequency of the generated square wave are used for comparison. Results:

	Filename	Flash Memory Usage	Output Frequency
Arduino	Arduino-Benchmark.ino	1,354 bytes	64.91 kHz
Pin Library	Pin-Library-Benchmark.ino	1,164 bytes	532.3 kHz
Direct Port Manipulation	Port-Manipulation-Benchmark.ino	648 bytes	2661 kHz

Usage

Install

Install from the Arduino Library Manager or download the latest release here.

Import Pin Library

Without support for simultaneous operations

#include <Pin.h>

Create Pin Object

Single Pin

Pin myPin = Pin(5);

Array of Pins

Pin myPins[] = {6,7};

Use as Input

Set mode to input

myPin.setInput();

Enable pullup resistor

myPin.setPullupOn();

Disable pullup resistor

myPin.setPullupOff();

Use as Output

Set mode to output

myPin.setOutput();

Set HIGH

myPin.setHigh();

myPin = HIGH;

Set LOW

myPin.setLow();

myPin = LOW;

Get Pin Info

Get mode (INPUT/OUTPUT)

myPin.getMode();

Get state (HIGH/LOW)

myPin.getState();

Get value (HIGH/LOW)

myPin.getValue();

myPin == HIGH;

myPin == LOW;

Get analog value (0-1023)

myPin.getAnalogValue();

Toggle

Toggle mode (OUTPUT -> INPUT, INPUT -> OUTPUT)

myPin.toggleMode();

Toggle state (HIGH -> LOW, LOW -> HIGH)

myPin.toggleState();

PWM

Set duty cycle to ~50% (not every Pin supports PWM)

myPin.setDutyCycle(127);

RC Timer

Special function specifically for timing using series resistor-capacitor circuits. Used to get analog information on digital pins. Connect the pin between the variable resistor (force sensitive resistor, photoresistor, etc.) and the capacitor. The function will charge the capacitor through the resistor and count down the timer until it is charged (50% voltage is considered charged). Finally, the capacitor is discharged to allow the function to be called again.

The function returns the value remaining on the counter when the pin state went to HIGH or 0 if the counter reached 0. The higher the resistance, the longer the capacitor will take to charge. Longer charge times mean the counter will be decremented more resulting in a lower value returned. Therefore, higher resistance -> lower value returned, lower resistance -> higher value returned.

Decrement a counter starting at 255 until the pin goes HIGH or the counter reaches 0

myPin.setLow();
myPin.rcTimer(255);

Simultaneous Operations on Multiple Pins

All Pins in array must use the same DDR, PORT, and PIN registers. Look at the Arduino documentation for your board to determine what registers each pin uses. Because this library is built for speed, the Pin Group is not automatically checked to be valid for simultaneous operations. An invalid array will produce unexpected results without error, therefore it is highly recommended that the array be validated using the isValid() function during setup.

Import Pin Library with support for simultaneous operations

#include <Pin.h>
#include <PinGroup.h>

Create array of Pins for simultaneous operations

Pin myPins[] = {Pin(2),Pin(3),Pin(5)};
PinGroup myPinGroup = PinGroup(myPins);

Check to ensure each Pin in PinGroup use the same registers

myPinGroup.isValid();

Simultaneously set mode for each Pin in PinGroup to INPUT

myPinGroup.setInput();

Simultaneously set mode for each Pin in PinGroup to OUTPUT

myPinGroup.setOutput();

Simultaneously set state for each Pin in PinGroup to HIGH

myPinGroup.setHigh();

Simultaneously set state for each Pin in PinGroup to LOW

myPinGroup.setLow();

Simultaneously check if each Pin in PinGroup is HIGH

myPinGroup.getValue() == HIGH;

Simultaneously check if each Pin in PinGroup is LOW

myPinGroup.getValue() == LOW;

Simultaneously set each Pin in PinGroup to its opposite mode

myPinGroup.toggleMode();

Simultaneously set each Pin in PinGroup to its opposite state

myPinGroup.toggleState();