Skip to content
Branch: master
Find file Copy path
Find file Copy path
Fetching contributors…
Cannot retrieve contributors at this time
113 lines (97 sloc) 3.72 KB
* @file GPIO.h
* @author Derek Molloy
* @version 0.1
* Created on: 29 Apr 2014
* Copyright (c) 2014 Derek Molloy (
* Made available for the book "Exploring BeagleBone"
* See:
* Licensed under the EUPL V.1.1
* This Software is provided to You under the terms of the European
* Union Public License (the "EUPL") version 1.1 as published by the
* European Union. Any use of this Software, other than as authorized
* under this License is strictly prohibited (to the extent such use
* is covered by a right of the copyright holder of this Software).
* This Software is provided under the License on an "AS IS" basis and
* without warranties of any kind concerning the Software, including
* without limitation merchantability, fitness for a particular purpose,
* absence of defects or errors, accuracy, and non-infringement of
* intellectual property rights other than copyright. This disclaimer
* of warranty is an essential part of the License and a condition for
* the grant of any rights to this Software.
* For more details, see
#ifndef GPIO_H_
#define GPIO_H_
using std::string;
using std::ofstream;
#define GPIO_PATH "/sys/class/gpio/"
namespace exploringBB {
typedef int (*CallbackType)(int);
* @class GPIO
* @brief GPIO class for input and output functionality on a single GPIO pin
class GPIO {
enum VALUE{ LOW=0, HIGH=1 };
int number; /**< The GPIO number of the object */
int debounceTime; /**< The debounce time in milliseconds */
string name; /**< The name of the GPIO e.g. gpio50 */
string path; /**< The full path to the GPIO e.g. /sys/class/gpio/gpio50/ */
GPIO(int number);
virtual int getNumber() { return number; } /**< Returns the GPIO number as an int. */
// General Input and Output Settings
virtual int setDirection(GPIO::DIRECTION);
virtual GPIO::DIRECTION getDirection();
virtual int setValue(GPIO::VALUE);
virtual int toggleOutput();
virtual GPIO::VALUE getValue();
virtual int setActiveLow(bool isLow=true); //low=1, high=0
virtual int setActiveHigh(); //default
//software debounce input (ms) - default 0
virtual void setDebounceTime(int time) { this->debounceTime = time; }
// Advanced OUTPUT: Faster write by keeping the stream alive (~20X)
virtual int streamOpen();
virtual int streamWrite(GPIO::VALUE);
virtual int streamClose();
virtual int toggleOutput(int time); //threaded invert output every X ms.
virtual int toggleOutput(int numberOfTimes, int time);
virtual void changeToggleTime(int time) { this->togglePeriod = time; }
virtual void toggleCancel() { this->threadRunning = false; }
// Advanced INPUT: Detect input edges; threaded and non-threaded
virtual int setEdgeType(GPIO::EDGE);
virtual GPIO::EDGE getEdgeType();
virtual int waitForEdge(); // waits until button is pressed
virtual int waitForEdge(CallbackType callback); // threaded with callback
virtual void waitForEdgeCancel() { this->threadRunning = false; }
virtual ~GPIO(); //destructor will unexport the pin
//int write(string path, string filename, string value);
//int write(string path, string filename, int value);
//string read(string path, string filename);
int exportGPIO();
int unexportGPIO();
ofstream stream;
pthread_t thread;
CallbackType callbackFunction;
bool threadRunning;
int togglePeriod; //default 100ms
int toggleNumber; //default -1 (infinite)
friend void* threadedPoll(void *value);
friend void* threadedToggle(void *value);
void* threadedPoll(void *value);
void* threadedToggle(void *value);
} /* namespace exploringBB */
#endif /* GPIO_H_ */
You can’t perform that action at this time.