159 lines
3.5 KiB
C
159 lines
3.5 KiB
C
/*
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* wfi.c:
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* Wait for Interrupt test program
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*
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* Copyright (c) 2012 Gordon Henderson.
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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 <stdlib.h>
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#include <wiringPi.h>
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// A 'key' which we can lock and unlock - values are 0 through 3
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// This is interpreted internally as a pthread_mutex by wiringPi
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// which is hiding some of that to make life simple.
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#define COUNT_KEY 0
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// What BCM_GPIO input are we using?
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// GPIO 0 is one of the I2C pins with an on-board pull-up
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#define BUTTON_PIN 0
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// Debounce time in mS
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#define DEBOUNCE_TIME 100
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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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* waitForIt:
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* This is a thread created using the wiringPi simplified threading
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* mechanism. It will wait on an interrupt on the button and increment
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* a counter.
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*********************************************************************************
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*/
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PI_THREAD (waitForIt)
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{
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int state = 0 ;
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int debounceTime = 0 ;
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(void)piHiPri (10) ; // Set this thread to be high priority
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digitalWrite (18, 1) ;
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for (;;)
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{
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if (waitForInterrupt (BUTTON_PIN, -1) > 0) // Got it
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{
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// Bouncing?
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if (millis () < debounceTime)
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{
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debounceTime = millis () + DEBOUNCE_TIME ;
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continue ;
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}
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// We have a valid one
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digitalWrite (17, state) ;
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state ^= 1 ;
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piLock (COUNT_KEY) ;
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++globalCounter ;
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piUnlock (COUNT_KEY) ;
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// Wait for key to be released
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while (digitalRead (0) == LOW)
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delay (1) ;
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debounceTime = millis () + DEBOUNCE_TIME ;
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}
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}
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}
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/*
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* setup:
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* Demo a crude but effective way to initialise the hardware
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*********************************************************************************
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*/
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void setup (void)
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{
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// Use the gpio program to initialise the hardware
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// (This is the crude, but effective bit)
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system ("gpio edge 0 falling") ;
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system ("gpio export 17 out") ;
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system ("gpio export 18 out") ;
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// Setup wiringPi
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wiringPiSetupSys () ;
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// Fire off our interrupt handler
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piThreadCreate (waitForIt) ;
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digitalWrite (17, 0) ;
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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 lastCounter = 0 ;
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int myCounter = 0 ;
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setup () ;
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for (;;)
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{
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printf ("Waiting ... ") ; fflush (stdout) ;
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while (myCounter == lastCounter)
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{
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piLock (COUNT_KEY) ;
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myCounter = globalCounter ;
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piUnlock (COUNT_KEY) ;
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delay (5000) ;
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}
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printf (" Done. myCounter: %5d\n", myCounter) ;
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lastCounter = myCounter ;
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}
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return 0 ;
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}
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