119 lines
3.2 KiB
C
119 lines
3.2 KiB
C
/*
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* isr-osc.c:
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* Wait for Interrupt test program - ISR method - interrupt oscillator
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*
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* How to test:
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*
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* IMPORTANT: To run this test we connect 2 GPIO pins together, but
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* before we do that YOU must make sure that they are both setup
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* the right way. If they are set to outputs and one is high and one low,
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* then you connect the wire, you'll create a short and that won't be good.
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*
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* Before making the connection, type:
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* gpio mode 0 output
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* gpio write 0 0
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* gpio mode 1 input
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* then you can connect them together.
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*
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* Run the program, then:
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* gpio write 0 1
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* gpio write 0 0
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*
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* at which point it will trigger an interrupt and the program will
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* then do the up/down toggling for itself and run at full speed, and
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* it will report the number of interrupts recieved every second.
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*
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* Copyright (c) 2013 Gordon Henderson. projects@drogon.net
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***********************************************************************
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* This file is part of wiringPi:
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* https://projects.drogon.net/raspberry-pi/wiringpi/
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*
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* wiringPi is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* wiringPi is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with wiringPi. If not, see <http://www.gnu.org/licenses/>.
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***********************************************************************
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*/
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#include <stdio.h>
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#include <string.h>
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#include <errno.h>
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#include <stdlib.h>
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#include <wiringPi.h>
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// What GPIO input are we using?
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// This is a wiringPi pin number
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#define OUT_PIN 0
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#define IN_PIN 1
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// globalCounter:
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// Global variable to count interrupts
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// Should be declared volatile to make sure the compiler doesn't cache it.
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static volatile int globalCounter = 0 ;
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/*
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* myInterrupt:
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*********************************************************************************
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*/
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void myInterrupt (void)
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{
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digitalWrite (OUT_PIN, 1) ;
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++globalCounter ;
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digitalWrite (OUT_PIN, 0) ;
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}
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/*
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*********************************************************************************
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* main
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*********************************************************************************
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*/
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int main (void)
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{
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int myCounter = 0 ;
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int lastCounter = 0 ;
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if (wiringPiSetup () < 0)
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{
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fprintf (stderr, "Unable to setup wiringPi: %s\n", strerror (errno)) ;
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return 1 ;
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}
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pinMode (OUT_PIN, OUTPUT) ;
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pinMode (IN_PIN, INPUT) ;
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if (wiringPiISR (IN_PIN, INT_EDGE_FALLING, &myInterrupt) < 0)
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{
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fprintf (stderr, "Unable to setup ISR: %s\n", strerror (errno)) ;
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return 1 ;
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}
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for (;;)
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{
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printf ("Waiting ... ") ; fflush (stdout) ;
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while (myCounter == globalCounter)
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delay (1000) ;
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printf (" Done. counter: %6d: %6d\n",
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globalCounter, myCounter - lastCounter) ;
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lastCounter = myCounter ;
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myCounter = globalCounter ;
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}
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return 0 ;
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}
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