gpio/gpio.c

/*
 * gpio.c:
 *	Swiss-Army-Knife, Set-UID command-line interface to the Raspberry
 *	Pi's GPIO.
 *	Copyright (c) 2012-2013 Gordon Henderson
 ***********************************************************************
 * This file is part of wiringPi:
 *	https://projects.drogon.net/raspberry-pi/wiringpi/
 *
 *    wiringPi is free software: you can redistribute it and/or modify
 *    it under the terms of the GNU Lesser General Public License as published by
 *    the Free Software Foundation, either version 3 of the License, or
 *    (at your option) any later version.
 *
 *    wiringPi is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU Lesser General Public License for more details.
 *
 *    You should have received a copy of the GNU Lesser General Public License
 *    along with wiringPi.  If not, see <http://www.gnu.org/licenses/>.
 ***********************************************************************
 */


#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <ctype.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>

#include <wiringPi.h>

#include <gertboard.h>
#include <piFace.h>

#include "extensions.h"

extern int wiringPiDebug ;

#ifndef TRUE
#  define	TRUE	(1==1)
#  define	FALSE	(1==2)
#endif

#define	VERSION		"2.02"
#define	I2CDETECT	"/usr/sbin/i2cdetect"

static int wpMode ;

char *usage = "Usage: gpio -v\n"
              "       gpio -h\n"
              "       gpio [-g|-1] [-x extension:params] ...\n"
              "       gpio [-p] <read/write/wb> ...\n"
              "       gpio <read/write/aread/awritewb/pwm/clock/mode> ...\n"
	      "       gpio readall/reset\n"
	      "       gpio unexportall/exports\n"
	      "       gpio export/edge/unexport ...\n"
	      "       gpio wfi <pin> <mode>\n"
	      "       gpio drive <group> <value>\n"
	      "       gpio pwm-bal/pwm-ms \n"
	      "       gpio pwmr <range> \n"
	      "       gpio pwmc <divider> \n"
	      "       gpio load spi/i2c\n"
	      "       gpio i2cd/i2cdetect\n"
	      "       gpio gbr <channel>\n"
	      "       gpio gbw <channel> <value>" ;	// No trailing newline needed here.


/*
 * changeOwner:
 *	Change the ownership of the file to the real userId of the calling
 *	program so we can access it.
 *********************************************************************************
 */

static void changeOwner (char *cmd, char *file)
{
  uid_t uid = getuid () ;
  uid_t gid = getgid () ;

  if (chown (file, uid, gid) != 0)
  {
    if (errno == ENOENT)	// Warn that it's not there
      fprintf (stderr, "%s: Warning: File not present: %s\n", cmd, file) ;
    else
    {
      fprintf (stderr, "%s: Unable to change ownership of %s: %s\n", cmd, file, strerror (errno)) ;
      exit (1) ;
    }
  }
}


/*
 * moduleLoaded:
 *	Return true/false if the supplied module is loaded
 *********************************************************************************
 */

static int moduleLoaded (char *modName)
{
  int len   = strlen (modName) ;
  int found = FALSE ;
  FILE *fd = fopen ("/proc/modules", "r") ;
  char line [80] ;

  if (fd == NULL)
  {
    fprintf (stderr, "gpio: Unable to check modules: %s\n", strerror (errno)) ;
    exit (1) ;
  }

  while (fgets (line, 80, fd) != NULL)
  {
    if (strncmp (line, modName, len) != 0)
      continue ;

    found = TRUE ;
    break ;
  }

  fclose (fd) ;

  return found ;
}


/*
 * doLoad:
 *	Load either the spi or i2c modules and change device ownerships, etc.
 *********************************************************************************
 */

static void _doLoadUsage (char *argv [])
{
  fprintf (stderr, "Usage: %s load <spi/i2c> [SPI bufferSize in KB | I2C baudrate in Kb/sec]\n", argv [0]) ;
  exit (1) ;
}

static void doLoad (int argc, char *argv [])
{
  char *module1, *module2 ;
  char cmd [80] ;
  char *file1, *file2 ;
  char args1 [32], args2 [32] ;

  if (argc < 3)
    _doLoadUsage (argv) ;

  args1 [0] = args2 [0] = 0 ;

  /**/ if (strcasecmp (argv [2], "spi") == 0)
  {
    module1 = "spidev" ;
    module2 = "spi_bcm2708" ;
    file1  = "/dev/spidev0.0" ;
    file2  = "/dev/spidev0.1" ;
    if (argc == 4)
      sprintf (args1, " bufsiz=%d", atoi (argv [3]) * 1024) ;
    else if (argc > 4)
      _doLoadUsage (argv) ;
  }
  else if (strcasecmp (argv [2], "i2c") == 0)
  {
    module1 = "i2c_dev" ;
    module2 = "i2c_bcm2708" ;
    file1  = "/dev/i2c-0" ;
    file2  = "/dev/i2c-1" ;
    if (argc == 4)
      sprintf (args2, " baudrate=%d", atoi (argv [3]) * 1000) ;
    else if (argc > 4)
      _doLoadUsage (argv) ;
  }
  else
    _doLoadUsage (argv) ;

  if (!moduleLoaded (module1))
  {
    sprintf (cmd, "modprobe %s%s", module1, args1) ;
    system (cmd) ;
  }

  if (!moduleLoaded (module2))
  {
    sprintf (cmd, "modprobe %s%s", module2, args2) ;
    system (cmd) ;
  }

  if (!moduleLoaded (module2))
  {
    fprintf (stderr, "%s: Unable to load %s\n", argv [0], module2) ;
    exit (1) ;
  }

  sleep (1) ;	// To let things get settled

  changeOwner (argv [0], file1) ;
  changeOwner (argv [0], file2) ;
}


/*
 * doI2Cdetect:
 *	Run the i2cdetect command with the right runes for this Pi revision
 *********************************************************************************
 */

static void doI2Cdetect (int argc, char *argv [])
{
  int port = piBoardRev () == 1 ? 0 : 1 ;
  char command [128] ;
  struct stat statBuf ;

  if (stat (I2CDETECT, &statBuf) < 0)
  {
    fprintf (stderr, "%s: Unable to find i2cdetect command: %s\n", argv [0], strerror (errno)) ;
    return ;
  }

  if (!moduleLoaded ("i2c_dev"))
  {
    fprintf (stderr, "%s: The I2C kernel module(s) are not loaded.\n", argv [0]) ;
    return ;
  }

  sprintf (command, "%s -y %d", I2CDETECT, port) ;
  if (system (command) < 0)
    fprintf (stderr, "%s: Unable to run i2cdetect: %s\n", argv [0], strerror (errno)) ;

}


/*
 * doReadall:
 *	Read all the GPIO pins
 *********************************************************************************
 */

static char *pinNames [] =
{
  "GPIO 0", "GPIO 1", "GPIO 2", "GPIO 3", "GPIO 4", "GPIO 5", "GPIO 6", "GPIO 7",
  "SDA   ", "SCL   ",
  "CE0   ", "CE1   ", "MOSI  ", "MISO  ", "SCLK  ",
  "TxD   ", "RxD   ",
  "GPIO 8", "GPIO 9", "GPIO10", "GPIO11",
} ;

static char *alts [] =
{
  "IN  ", "OUT ", "ALT5", "ALT4", "ALT0", "ALT1", "ALT2", "ALT3"
} ;

static int wpiToPhys [64] =
{
  11, 12, 13, 15, 16, 18, 22,  7,	//  0...7
   3,  5,				//  8...9
  24, 26, 19, 21, 23,			// 10..14
   8, 10,				// 15..16
   3,  4,  5,  6,			// 17..20
             0,0,0,0,0,0,0,0,0,0,0,	// 20..31
   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,	// 32..47
   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,	// 47..63
} ;

static void doReadall (void)
{
  int pin ;

  printf ("+----------+-Rev%d-+------+--------+------+-------+\n", piBoardRev ()) ;
  printf ("| wiringPi | GPIO | Phys | Name   | Mode | Value |\n") ;
  printf ("+----------+------+------+--------+------+-------+\n") ;

  for (pin = 0 ; pin < 64 ; ++pin)	// Crude, but effective
  {
    if (wpiPinToGpio (pin) == -1)
      continue ;

    printf ("| %6d   | %3d  | %3d  | %s | %s | %s  |\n",
	pin, wpiPinToGpio (pin), wpiToPhys [pin],
	pinNames [pin], 
	alts [getAlt (pin)], 
	digitalRead (pin) == HIGH ? "High" : "Low ") ;
  }

  printf ("+----------+------+------+--------+------+-------+\n") ;
}


/*
 * doExports:
 *	List all GPIO exports
 *********************************************************************************
 */

static void doExports (int argc, char *argv [])
{
  int fd ;
  int i, l, first ;
  char fName [128] ;
  char buf [16] ;

  for (first = 0, i = 0 ; i < 64 ; ++i)	// Crude, but effective
  {

// Try to read the direction

    sprintf (fName, "/sys/class/gpio/gpio%d/direction", i) ;
    if ((fd = open (fName, O_RDONLY)) == -1)
      continue ;

    if (first == 0)
    {
      ++first ;
      printf ("GPIO Pins exported:\n") ;
    }

    printf ("%4d: ", i) ;

    if ((l = read (fd, buf, 16)) == 0)
      sprintf (buf, "%s", "?") ;
 
    buf [l] = 0 ;
    if ((buf [strlen (buf) - 1]) == '\n')
      buf [strlen (buf) - 1] = 0 ;

    printf ("%-3s", buf) ;

    close (fd) ;

// Try to Read the value

    sprintf (fName, "/sys/class/gpio/gpio%d/value", i) ;
    if ((fd = open (fName, O_RDONLY)) == -1)
    {
      printf ("No Value file (huh?)\n") ;
      continue ;
    }

    if ((l = read (fd, buf, 16)) == 0)
      sprintf (buf, "%s", "?") ;

    buf [l] = 0 ;
    if ((buf [strlen (buf) - 1]) == '\n')
      buf [strlen (buf) - 1] = 0 ;

    printf ("  %s", buf) ;

// Read any edge trigger file

    sprintf (fName, "/sys/class/gpio/gpio%d/edge", i) ;
    if ((fd = open (fName, O_RDONLY)) == -1)
    {
      printf ("\n") ;
      continue ;
    }

    if ((l = read (fd, buf, 16)) == 0)
      sprintf (buf, "%s", "?") ;

    buf [l] = 0 ;
    if ((buf [strlen (buf) - 1]) == '\n')
      buf [strlen (buf) - 1] = 0 ;

    printf ("  %-8s\n", buf) ;

    close (fd) ;
  }
}


/*
 * doExport:
 *	gpio export pin mode
 *	This uses the /sys/class/gpio device interface.
 *********************************************************************************
 */

void doExport (int argc, char *argv [])
{
  FILE *fd ;
  int pin ;
  char *mode ;
  char fName [128] ;

  if (argc != 4)
  {
    fprintf (stderr, "Usage: %s export pin mode\n", argv [0]) ;
    exit (1) ;
  }

  pin = atoi (argv [2]) ;

  mode = argv [3] ;

  if ((fd = fopen ("/sys/class/gpio/export", "w")) == NULL)
  {
    fprintf (stderr, "%s: Unable to open GPIO export interface: %s\n", argv [0], strerror (errno)) ;
    exit (1) ;
  }

  fprintf (fd, "%d\n", pin) ;
  fclose (fd) ;

  sprintf (fName, "/sys/class/gpio/gpio%d/direction", pin) ;
  if ((fd = fopen (fName, "w")) == NULL)
  {
    fprintf (stderr, "%s: Unable to open GPIO direction interface for pin %d: %s\n", argv [0], pin, strerror (errno)) ;
    exit (1) ;
  }

  /**/ if ((strcasecmp (mode, "in")  == 0) || (strcasecmp (mode, "input")  == 0))
    fprintf (fd, "in\n") ;
  else if ((strcasecmp (mode, "out") == 0) || (strcasecmp (mode, "output") == 0))
    fprintf (fd, "out\n") ;
  else
  {
    fprintf (stderr, "%s: Invalid mode: %s. Should be in or out\n", argv [1], mode) ;
    exit (1) ;
  }

  fclose (fd) ;

// Change ownership so the current user can actually use it!

  sprintf (fName, "/sys/class/gpio/gpio%d/value", pin) ;
  changeOwner (argv [0], fName) ;

  sprintf (fName, "/sys/class/gpio/gpio%d/edge", pin) ;
  changeOwner (argv [0], fName) ;

}


/*
 * doWfi:
 *	gpio wfi pin mode
 *	Wait for Interrupt on a given pin.
 *	Slight cheat here - it's easier to actually use ISR now (which calls
 *	gpio to set the pin modes!) then we simply sleep, and expect the thread
 *	to exit the program. Crude but effective.
 *********************************************************************************
 */

static void wfi (void)
  { exit (0) ; }

void doWfi (int argc, char *argv [])
{
  int pin, mode ;

  if (argc != 4)
  {
    fprintf (stderr, "Usage: %s wfi pin mode\n", argv [0]) ;
    exit (1) ;
  }

  pin  = atoi (argv [2]) ;

  /**/ if (strcasecmp (argv [3], "rising")  == 0) mode = INT_EDGE_RISING ;
  else if (strcasecmp (argv [3], "falling") == 0) mode = INT_EDGE_FALLING ;
  else if (strcasecmp (argv [3], "both")    == 0) mode = INT_EDGE_BOTH ;
  else
  {
    fprintf (stderr, "%s: wfi: Invalid mode: %s. Should be rising, falling or both\n", argv [1], argv [3]) ;
    exit (1) ;
  }

  if (wiringPiISR (pin, mode, &wfi) < 0)
  {
    fprintf (stderr, "%s: wfi: Unable to setup ISR: %s\n", argv [1], strerror (errno)) ;
    exit (1) ;
  }

  for (;;)
    delay (9999) ;
}



/*
 * doEdge:
 *	gpio edge pin mode
 *	Easy access to changing the edge trigger on a GPIO pin
 *	This uses the /sys/class/gpio device interface.
 *********************************************************************************
 */

void doEdge (int argc, char *argv [])
{
  FILE *fd ;
  int pin ;
  char *mode ;
  char fName [128] ;

  if (argc != 4)
  {
    fprintf (stderr, "Usage: %s edge pin mode\n", argv [0]) ;
    exit (1) ;
  }

  pin  = atoi (argv [2]) ;
  mode = argv [3] ;

// Export the pin and set direction to input

  if ((fd = fopen ("/sys/class/gpio/export", "w")) == NULL)
  {
    fprintf (stderr, "%s: Unable to open GPIO export interface: %s\n", argv [0], strerror (errno)) ;
    exit (1) ;
  }

  fprintf (fd, "%d\n", pin) ;
  fclose (fd) ;

  sprintf (fName, "/sys/class/gpio/gpio%d/direction", pin) ;
  if ((fd = fopen (fName, "w")) == NULL)
  {
    fprintf (stderr, "%s: Unable to open GPIO direction interface for pin %d: %s\n", argv [0], pin, strerror (errno)) ;
    exit (1) ;
  }

  fprintf (fd, "in\n") ;
  fclose (fd) ;

  sprintf (fName, "/sys/class/gpio/gpio%d/edge", pin) ;
  if ((fd = fopen (fName, "w")) == NULL)
  {
    fprintf (stderr, "%s: Unable to open GPIO edge interface for pin %d: %s\n", argv [0], pin, strerror (errno)) ;
    exit (1) ;
  }

  /**/ if (strcasecmp (mode, "none")    == 0) fprintf (fd, "none\n") ;
  else if (strcasecmp (mode, "rising")  == 0) fprintf (fd, "rising\n") ;
  else if (strcasecmp (mode, "falling") == 0) fprintf (fd, "falling\n") ;
  else if (strcasecmp (mode, "both")    == 0) fprintf (fd, "both\n") ;
  else
  {
    fprintf (stderr, "%s: Invalid mode: %s. Should be none, rising, falling or both\n", argv [1], mode) ;
    exit (1) ;
  }

// Change ownership of the value and edge files, so the current user can actually use it!

  sprintf (fName, "/sys/class/gpio/gpio%d/value", pin) ;
  changeOwner (argv [0], fName) ;

  sprintf (fName, "/sys/class/gpio/gpio%d/edge", pin) ;
  changeOwner (argv [0], fName) ;

  fclose (fd) ;
}


/*
 * doUnexport:
 *	gpio unexport pin
 *	This uses the /sys/class/gpio device interface.
 *********************************************************************************
 */

void doUnexport (int argc, char *argv [])
{
  FILE *fd ;
  int pin ;

  if (argc != 3)
  {
    fprintf (stderr, "Usage: %s unexport pin\n", argv [0]) ;
    exit (1) ;
  }

  pin = atoi (argv [2]) ;

  if ((fd = fopen ("/sys/class/gpio/unexport", "w")) == NULL)
  {
    fprintf (stderr, "%s: Unable to open GPIO export interface\n", argv [0]) ;
    exit (1) ;
  }

  fprintf (fd, "%d\n", pin) ;
  fclose (fd) ;
}


/*
 * doUnexportAll:
 *	gpio unexportall
 *	Un-Export all the GPIO pins.
 *	This uses the /sys/class/gpio device interface.
 *********************************************************************************
 */

void doUnexportall (char *progName)
{
  FILE *fd ;
  int pin ;

  for (pin = 0 ; pin < 63 ; ++pin)
  {
    if ((fd = fopen ("/sys/class/gpio/unexport", "w")) == NULL)
    {
      fprintf (stderr, "%s: Unable to open GPIO export interface\n", progName) ;
      exit (1) ;
    }
    fprintf (fd, "%d\n", pin) ;
    fclose (fd) ;
  }
}


/*
 * doReset:
 *	Reset the GPIO pins - as much as we can do
 *********************************************************************************
 */

static void doReset (char *progName)
{
  int pin ;

  doUnexportall (progName) ;

  for (pin = 0 ; pin < 64 ; ++pin)
  {
    if (wpiPinToGpio (pin) == -1)
      continue ;

    digitalWrite    (pin, LOW) ;
    pinMode         (pin, INPUT) ;
    pullUpDnControl (pin, PUD_OFF) ;
  }
}


/*
 * doMode:
 *	gpio mode pin mode ...
 *********************************************************************************
 */

void doMode (int argc, char *argv [])
{
  int pin ;
  char *mode ;

  if (argc != 4)
  {
    fprintf (stderr, "Usage: %s mode pin mode\n", argv [0]) ;
    exit (1) ;
  }

  pin = atoi (argv [2]) ;

  mode = argv [3] ;

  /**/ if (strcasecmp (mode, "in")     == 0) pinMode         (pin, INPUT) ;
  else if (strcasecmp (mode, "out")    == 0) pinMode         (pin, OUTPUT) ;
  else if (strcasecmp (mode, "pwm")    == 0) pinMode         (pin, PWM_OUTPUT) ;
  else if (strcasecmp (mode, "clock")  == 0) pinMode         (pin, GPIO_CLOCK) ;
  else if (strcasecmp (mode, "up")     == 0) pullUpDnControl (pin, PUD_UP) ;
  else if (strcasecmp (mode, "down")   == 0) pullUpDnControl (pin, PUD_DOWN) ;
  else if (strcasecmp (mode, "tri")    == 0) pullUpDnControl (pin, PUD_OFF) ;
  else
  {
    fprintf (stderr, "%s: Invalid mode: %s. Should be in/out/pwm/clock/up/down/tri\n", argv [1], mode) ;
    exit (1) ;
  }
}


/*
 * doPadDrive:
 *	gpio drive group value
 *********************************************************************************
 */

static void doPadDrive (int argc, char *argv [])
{
  int group, val ;

  if (argc != 4)
  {
    fprintf (stderr, "Usage: %s drive group value\n", argv [0]) ;
    exit (1) ;
  }

  group = atoi (argv [2]) ;
  val   = atoi (argv [3]) ;

  if ((group < 0) || (group > 2))
  {
    fprintf (stderr, "%s: drive group not 0, 1 or 2: %d\n", argv [0], group) ;
    exit (1) ;
  }

  if ((val < 0) || (val > 7))
  {
    fprintf (stderr, "%s: drive value not 0-7: %d\n", argv [0], val) ;
    exit (1) ;
  }

  setPadDrive (group, val) ;
}


/*
 * doGbw:
 *	gpio gbw channel value
 *	Gertboard Write - To the Analog output
 *********************************************************************************
 */

static void doGbw (int argc, char *argv [])
{
  int channel, value ;

  if (argc != 4)
  {
    fprintf (stderr, "Usage: %s gbw <channel> <value>\n", argv [0]) ;
    exit (1) ;
  }

  channel = atoi (argv [2]) ;
  value   = atoi (argv [3]) ;

  if ((channel < 0) || (channel > 1))
  {
    fprintf (stderr, "%s: gbw: Channel number must be 0 or 1\n", argv [0]) ;
    exit (1) ;
  }

  if ((value < 0) || (value > 1023))
  {
    fprintf (stderr, "%s: gbw: Value must be from 0 to 255\n", argv [0]) ;
    exit (1) ;
  }

  if (gertboardAnalogSetup (64) < 0)
  {
    fprintf (stderr, "Unable to initialise the Gertboard SPI interface: %s\n", strerror (errno)) ;
    exit (1) ;
  }

  analogWrite (64 + channel, value) ;
}


/*
 * doGbr:
 *	gpio gbr channel
 *	From the analog input
 *********************************************************************************
 */

static void doGbr (int argc, char *argv [])
{
  int channel ;

  if (argc != 3)
  {
    fprintf (stderr, "Usage: %s gbr <channel>\n", argv [0]) ;
    exit (1) ;
  }

  channel = atoi (argv [2]) ;

  if ((channel < 0) || (channel > 1))
  {
    fprintf (stderr, "%s: gbr: Channel number must be 0 or 1\n", argv [0]) ;
    exit (1) ;
  }

  if (gertboardAnalogSetup (64) < 0)
  {
    fprintf (stderr, "Unable to initialise the Gertboard SPI interface: %s\n", strerror (errno)) ;
    exit (1) ;
  }

  printf ("%d\n", analogRead (64 + channel)) ;
}


/*
 * doWrite:
 *	gpio write pin value
 *********************************************************************************
 */

static void doWrite (int argc, char *argv [])
{
  int pin, val ;

  if (argc != 4)
  {
    fprintf (stderr, "Usage: %s write pin value\n", argv [0]) ;
    exit (1) ;
  }

  pin = atoi (argv [2]) ;

  /**/ if ((strcasecmp (argv [3], "up") == 0) || (strcasecmp (argv [3], "on") == 0))
    val = 1 ;
  else if ((strcasecmp (argv [3], "down") == 0) || (strcasecmp (argv [3], "off") == 0))
    val = 0 ;
  else
    val = atoi (argv [3]) ;

  /**/ if (val == 0)
    digitalWrite (pin, LOW) ;
  else
    digitalWrite (pin, HIGH) ;
}


/*
 * doAwriterite:
 *	gpio awrite pin value
 *********************************************************************************
 */

static void doAwrite (int argc, char *argv [])
{
  int pin, val ;

  if (argc != 4)
  {
    fprintf (stderr, "Usage: %s awrite pin value\n", argv [0]) ;
    exit (1) ;
  }

  pin = atoi (argv [2]) ;

  val = atoi (argv [3]) ;

  analogWrite (pin, val) ;
}


/*
 * doWriteByte:
 *	gpio write value
 *********************************************************************************
 */

static void doWriteByte (int argc, char *argv [])
{
  int val ;

  if (argc != 3)
  {
    fprintf (stderr, "Usage: %s wb value\n", argv [0]) ;
    exit (1) ;
  }

  val = (int)strtol (argv [2], NULL, 0) ;

  digitalWriteByte (val) ;
}


/*
 * doRead:
 *	Read a pin and return the value
 *********************************************************************************
 */

void doRead (int argc, char *argv []) 
{
  int pin, val ;

  if (argc != 3)
  {
    fprintf (stderr, "Usage: %s read pin\n", argv [0]) ;
    exit (1) ;
  }

  pin = atoi (argv [2]) ;
  val = digitalRead (pin) ;

  printf ("%s\n", val == 0 ? "0" : "1") ;
}


/*
 * doAread:
 *	Read an analog pin and return the value
 *********************************************************************************
 */

void doAread (int argc, char *argv []) 
{
  int pin, val ;

  if (argc != 3)
  {
    fprintf (stderr, "Usage: %s aread pin\n", argv [0]) ;
    exit (1) ;
  }

  pin = atoi (argv [2]) ;

  val = analogRead (pin) ;

  printf ("%s\n", val == 0 ? "0" : "1") ;
}


/*
 * doToggle:
 *	Toggle an IO pin
 *********************************************************************************
 */

void doToggle (int argc, char *argv [])
{
  int pin ;

  if (argc != 3)
  {
    fprintf (stderr, "Usage: %s toggle pin\n", argv [0]) ;
    exit (1) ;
  }

  pin = atoi (argv [2]) ;

  digitalWrite (pin, !digitalRead (pin)) ;
}

/*
 * doClock:
 *	Output a clock on a pin
 *********************************************************************************
 */

void doClock (int argc, char *argv [])
{
  int pin, freq ;

  if (argc != 4)
  {
    fprintf (stderr, "Usage: %s clock <pin> <freq>\n", argv [0]) ;
    exit (1) ;
  }

  pin = atoi (argv [2]) ;

  freq = atoi (argv [3]) ;

  gpioClockSet (pin, freq) ;
}


/*
 * doPwm:
 *	Output a PWM value on a pin
 *********************************************************************************
 */

void doPwm (int argc, char *argv [])
{
  int pin, val ;

  if (argc != 4)
  {
    fprintf (stderr, "Usage: %s pwm <pin> <value>\n", argv [0]) ;
    exit (1) ;
  }

  pin = atoi (argv [2]) ;

  val = atoi (argv [3]) ;

  pwmWrite (pin, val) ;
}


/*
 * doPwmMode: doPwmRange: doPwmClock:
 *	Change the PWM mode, range and clock divider values
 *********************************************************************************
 */

static void doPwmMode (int mode)
{
  pwmSetMode (mode) ;
}

static void doPwmRange (int argc, char *argv [])
{
  unsigned int range ;

  if (argc != 3)
  {
    fprintf (stderr, "Usage: %s pwmr <range>\n", argv [0]) ;
    exit (1) ;
  }

  range = (unsigned int)strtoul (argv [2], NULL, 10) ;

  if (range == 0)
  {
    fprintf (stderr, "%s: range must be > 0\n", argv [0]) ;
    exit (1) ;
  }

  pwmSetRange (range) ;
}

static void doPwmClock (int argc, char *argv [])
{
  unsigned int clock ;

  if (argc != 3)
  {
    fprintf (stderr, "Usage: %s pwmc <clock>\n", argv [0]) ;
    exit (1) ;
  }

  clock = (unsigned int)strtoul (argv [2], NULL, 10) ;

  if ((clock < 1) || (clock > 4095))
  {
    fprintf (stderr, "%s: clock must be between 0 and 4096\n", argv [0]) ;
    exit (1) ;
  }

  pwmSetClock (clock) ;
}


/*
 * main:
 *	Start here
 *********************************************************************************
 */

int main (int argc, char *argv [])
{
  int i ;

  if (getenv ("WIRINGPI_DEBUG") != NULL)
  {
    printf ("gpio: wiringPi debug mode enabled\n") ;
    wiringPiDebug = TRUE ;
  }

  if (argc == 1)
  {
    fprintf (stderr, "%s\n", usage) ;
    return 1 ;
  }

// Help

  if (strcasecmp (argv [1], "-h") == 0)
  {
    printf ("%s: %s\n", argv [0], usage) ;
    return 0 ;
  }

// Sort of a special:

  if (strcmp (argv [1], "-R") == 0)
  {
    printf ("%d\n", piBoardRev ()) ;
    return 0 ;
  }

// Version & Warranty

  if (strcmp (argv [1], "-V") == 0)
  {
    printf ("%d\n", piBoardRev ()) ;
    return 0 ;
  }

  if (strcmp (argv [1], "-v") == 0)
  {
    printf ("gpio version: %s\n", VERSION) ;
    printf ("Copyright (c) 2012-2013 Gordon Henderson\n") ;
    printf ("This is free software with ABSOLUTELY NO WARRANTY.\n") ;
    printf ("For details type: %s -warranty\n", argv [0]) ;
    printf ("\n") ;
    printf ("This Raspberry Pi is a revision %d board.\n", piBoardRev ()) ;
    return 0 ;
  }

  if (strcasecmp (argv [1], "-warranty") == 0)
  {
    printf ("gpio version: %s\n", VERSION) ;
    printf ("Copyright (c) 2012-2013 Gordon Henderson\n") ;
    printf ("\n") ;
    printf ("    This program is free software; you can redistribute it and/or modify\n") ;
    printf ("    it under the terms of the GNU Leser General Public License as published\n") ;
    printf ("    by the Free Software Foundation, either version 3 of the License, or\n") ;
    printf ("    (at your option) any later version.\n") ;
    printf ("\n") ;
    printf ("    This program is distributed in the hope that it will be useful,\n") ;
    printf ("    but WITHOUT ANY WARRANTY; without even the implied warranty of\n") ;
    printf ("    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the\n") ;
    printf ("    GNU Lesser General Public License for more details.\n") ;
    printf ("\n") ;
    printf ("    You should have received a copy of the GNU Lesser General Public License\n") ;
    printf ("    along with this program. If not, see <http://www.gnu.org/licenses/>.\n") ;
    printf ("\n") ;
    return 0 ;
  }

  if (geteuid () != 0)
  {
    fprintf (stderr, "%s: Must be root to run. Program should be suid root. This is an error.\n", argv [0]) ;
    return 1 ;
  }

// Initial test for /sys/class/gpio operations:

  /**/ if (strcasecmp (argv [1], "exports"    ) == 0)	{ doExports     (argc, argv) ;	return 0 ; }
  else if (strcasecmp (argv [1], "export"     ) == 0)	{ doExport      (argc, argv) ;	return 0 ; }
  else if (strcasecmp (argv [1], "edge"       ) == 0)	{ doEdge        (argc, argv) ;	return 0 ; }
  else if (strcasecmp (argv [1], "unexport"   ) == 0)	{ doUnexport    (argc, argv) ;	return 0 ; }
  else if (strcasecmp (argv [1], "unexportall") == 0)	{ doUnexportall (argv [0]) ;	return 0 ; }

// Check for load command:

  if (strcasecmp (argv [1], "load" ) == 0)	{ doLoad     (argc, argv) ; return 0 ; }

// Gertboard commands

  if (strcasecmp (argv [1], "gbr" ) == 0)	{ doGbr (argc, argv) ; return 0 ; }
  if (strcasecmp (argv [1], "gbw" ) == 0)	{ doGbw (argc, argv) ; return 0 ; }

// Check for -g argument

  /**/ if (strcasecmp (argv [1], "-g") == 0)
  {
    wiringPiSetupGpio () ;

    for (i = 2 ; i < argc ; ++i)
      argv [i - 1] = argv [i] ;
    --argc ;
    wpMode = WPI_MODE_GPIO ;
  }

// Check for -1 argument

  else if (strcasecmp (argv [1], "-1") == 0)
  {
    wiringPiSetupPhys () ;

    for (i = 2 ; i < argc ; ++i)
      argv [i - 1] = argv [i] ;
    --argc ;
    wpMode = WPI_MODE_PHYS ;
  }

// Check for -p argument for PiFace

  else if (strcasecmp (argv [1], "-p") == 0)
  {
    piFaceSetup (200) ;

    for (i = 2 ; i < argc ; ++i)
      argv [i - 1] = argv [i] ;
    --argc ;
    wpMode = WPI_MODE_PIFACE ;
  }

// Default to wiringPi mode

  else
  {
    wiringPiSetup () ;
    wpMode = WPI_MODE_PINS ;
  }

// Check for -x argument to load in a new extension

  if (strcasecmp (argv [1], "-x") == 0)
  {
    if (argc < 3)
    {
      fprintf (stderr, "%s: -x missing extension specification.\n", argv [0]) ;
      exit (EXIT_FAILURE) ;
    }

    if (!doExtension (argv [0], argv [2]))	// Prints its own error messages
      exit (EXIT_FAILURE) ;

    for (i = 3 ; i < argc ; ++i)
      argv [i - 2] = argv [i] ;
    argc -= 2 ;
  }

  if (argc <= 1)
  {
    fprintf (stderr, "%s: no command given\n", argv [0]) ;
    exit (EXIT_FAILURE) ;
  }

// Core wiringPi functions

  /**/ if (strcasecmp (argv [1], "mode"   ) == 0) doMode      (argc, argv) ;
  else if (strcasecmp (argv [1], "read"   ) == 0) doRead      (argc, argv) ;
  else if (strcasecmp (argv [1], "write"  ) == 0) doWrite     (argc, argv) ;
  else if (strcasecmp (argv [1], "pwm"    ) == 0) doPwm       (argc, argv) ;
  else if (strcasecmp (argv [1], "awrite" ) == 0) doAwrite    (argc, argv) ;
  else if (strcasecmp (argv [1], "aread"  ) == 0) doAread     (argc, argv) ;

// GPIO Nicies

  else if (strcasecmp (argv [1], "toggle" ) == 0) doToggle    (argc, argv) ;

// Pi Specifics

  else if (strcasecmp (argv [1], "pwm-bal"  ) == 0) doPwmMode   (PWM_MODE_BAL) ;
  else if (strcasecmp (argv [1], "pwm-ms"   ) == 0) doPwmMode   (PWM_MODE_MS) ;
  else if (strcasecmp (argv [1], "pwmr"     ) == 0) doPwmRange  (argc, argv) ;
  else if (strcasecmp (argv [1], "pwmc"     ) == 0) doPwmClock  (argc, argv) ;
  else if (strcasecmp (argv [1], "drive"    ) == 0) doPadDrive  (argc, argv) ;
  else if (strcasecmp (argv [1], "readall"  ) == 0) doReadall   () ;
  else if (strcasecmp (argv [1], "i2cdetect") == 0) doI2Cdetect (argc, argv) ;
  else if (strcasecmp (argv [1], "i2cd"     ) == 0) doI2Cdetect (argc, argv) ;
  else if (strcasecmp (argv [1], "reset"    ) == 0) doReset     (argv [0]) ;
  else if (strcasecmp (argv [1], "wb"       ) == 0) doWriteByte (argc, argv) ;
  else if (strcasecmp (argv [1], "clock"    ) == 0) doClock     (argc, argv) ;
  else if (strcasecmp (argv [1], "wfi"      ) == 0) doWfi       (argc, argv) ;
  else
  {
    fprintf (stderr, "%s: Unknown command: %s.\n", argv [0], argv [1]) ;
    exit (EXIT_FAILURE) ;
  }
  return 0 ;
}