/*
* isr-osc.c:
* Wait for Interrupt test program - ISR method - interrupt oscillator
*
* How to test:
*
* IMPORTANT: To run this test we connect 2 GPIO pins together, but
* before we do that YOU must make sure that they are both setup
* the right way. If they are set to outputs and one is high and one low,
* then you connect the wire, you'll create a short and that won't be good.
*
* Before making the connection, type:
* gpio mode 0 output
* gpio write 0 0
* gpio mode 1 input
* then you can connect them together.
*
* Run the program, then:
* gpio write 0 1
* gpio write 0 0
*
* at which point it will trigger an interrupt and the program will
* then do the up/down toggling for itself and run at full speed, and
* it will report the number of interrupts recieved every second.
*
* Copyright (c) 2013 Gordon Henderson. projects@drogon.net
***********************************************************************
* 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 .
***********************************************************************
*/
#include
#include
#include
#include
#include
#include
#include
#include
// What GPIO input are we using?
// This is a wiringPi pin number
#define OUT_PIN 0
#define IN_PIN 1
// globalCounter:
// Global variable to count interrupts
// Should be declared volatile to make sure the compiler doesn't cache it.
static volatile unsigned long globalCounter = 0 ;
/*
* myInterrupt:
*********************************************************************************
*/
void myInterrupt (void)
{
++globalCounter ;
// digitalWrite (OUT_PIN, globalCounter & 0x1 ) ;
}
int updateFile ( char *filename, unsigned long count )
{
char buf[32];
int fd;
if ((fd = open (filename, O_RDWR | O_CREAT)) < 0)
{
fprintf (stderr, "Unable to update file %s: %s\n", filename, strerror (errno)) ;
return 1 ;
}
sprintf(buf, "%lu", count);
write (fd, buf, strlen(buf)) ;
return close (fd) ;
}
unsigned long readFile ( char *filename )
{
char buf[32];
int fd;
if ((fd = open (filename, O_RDWR )) < 0)
{
fprintf (stderr, "Unable to read file %s: %s\n", filename, strerror (errno)) ;
return 0 ;
}
read(fd, buf, sizeof(buf));
close (fd) ;
return atol(buf);
}
/*
*********************************************************************************
* main
*********************************************************************************
*/
int main (int argc, char *argv[])
{
unsigned long myCounter = 0 ;
unsigned long lastCounter = 0 ;
// fprintf (stderr, "argc=%d\n" , argc);
if (argc != 2)
{
fprintf (stderr, "Usage: %s filename\n", argv[0]);
return 1 ;
}
if (wiringPiSetup () < 0)
{
fprintf (stderr, "Unable to setup wiringPi: %s\n", strerror (errno)) ;
return 1 ;
}
globalCounter = readFile(argv[1]);
pinMode (OUT_PIN, OUTPUT) ;
pinMode (IN_PIN, INPUT) ;
pullUpDnControl(IN_PIN, PUD_UP) ;
if (wiringPiISR (IN_PIN, INT_EDGE_FALLING, &myInterrupt) < 0)
{
fprintf (stderr, "Unable to setup ISR: %s\n", strerror (errno)) ;
return 1 ;
}
if (updateFile(argv[1], 0) != 0 )
{
return 1 ;
}
for (;;)
{
printf ("Waiting ... ") ; fflush (stdout) ;
while (myCounter == globalCounter)
delay (100) ;
if ( lastCounter != 0 ) {
printf (" Done. counter: %lu: %lu\n",
globalCounter, myCounter - lastCounter) ;
}
lastCounter = myCounter ;
myCounter = globalCounter ;
if ( lastCounter != 0 ) {
updateFile(argv[1], myCounter);
}
digitalWrite (OUT_PIN, globalCounter & 0x1 ) ;
}
return 0 ;
}