Gordon Henderson
13 years ago
parent
e636f6213b
commit
a20fb1b154
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#include <stdio.h>
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#include <errno.h>
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#include <string.h>
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#include <wiringPi.h>
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#include <softPwm.h>
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#define RANGE 100
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#define NUM_LEDS 12
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int ledMap [NUM_LEDS] = { 0, 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13 } ;
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int values [NUM_LEDS] = { 0, 17, 32, 50, 67, 85, 100, 85, 67, 50, 32, 17 } ;
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int main ()
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{
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int i, j ;
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if (wiringPiSetup () == -1)
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{
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fprintf (stdout, "oops: %s\n", strerror (errno)) ;
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return 1 ;
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}
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for (i = 0 ; i < NUM_LEDS ; ++i)
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{
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softPwmCreate (ledMap [i], 0, RANGE) ;
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printf ("%3d, %3d, %3d\n", i, ledMap [i], values [i]) ;
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}
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for (;;)
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{
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for (i = 0 ; i < NUM_LEDS ; ++i)
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softPwmWrite (ledMap [i], values [i]) ;
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delay (50) ;
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i = values [0] ;
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for (j = 0 ; j < NUM_LEDS - 1 ; ++j)
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values [j] = values [j + 1] ;
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values [NUM_LEDS - 1] = i ;
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}
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}
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/*
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* softPwm.c:
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* Provide 2 channels of software driven PWM.
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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
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* published by the Free Software Foundation, either version 3 of the
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* License, or (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
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* License along with wiringPi.
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* 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 <pthread.h>
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#include "wiringPi.h"
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#include "softPwm.h"
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#define MAX_PINS 64
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// The PWM Frequency is derived from the "pulse time" below. Essentially,
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// the frequency is a function of the range and this pulse time.
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// The total period will be range * pulse time in uS, so a pulse time
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// of 100 and a range of 100 gives a period of 100 * 100 = 10,000 uS
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// which is a frequency of 100Hz.
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//
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// It's possible to get a higher frequency by lowering the pulse time,
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// however CPU uage will skyrocket as wiringPi uses a hard-loop to time
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// periods under 100uS - this is because the Linux timer calls are just
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// accurate at all, and have an overhead.
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//
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// Another way to increase the frequency is to reduce the range - however
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// that reduces the overall output accuracy...
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#define PULSE_TIME 100
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static int marks [MAX_PINS] ;
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static int range [MAX_PINS] ;
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int newPin = -1 ;
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/*
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* softPwmThread:
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* Thread to do the actual PWM output
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*********************************************************************************
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*/
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static PI_THREAD (softPwmThread)
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{
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int pin, mark, space ;
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pin = newPin ;
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newPin = -1 ;
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piHiPri (50) ;
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for (;;)
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{
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mark = marks [pin] ;
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space = range [pin] - mark ;
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if (mark != 0)
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digitalWrite (pin, HIGH) ;
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delayMicroseconds (mark * 100) ;
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if (space != 0)
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digitalWrite (pin, LOW) ;
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delayMicroseconds (space * 100) ;
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}
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return NULL ;
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}
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void softPwmWrite (int pin, int value)
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{
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marks [pin] = value ;
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}
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/*
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* softPwmCreate:
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* Create a new PWM thread.
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*********************************************************************************
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*/
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int softPwmCreate (int pin, int initialValue, int pwmRange)
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{
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int res ;
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pinMode (pin, OUTPUT) ;
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digitalWrite (pin, LOW) ;
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marks [pin] = initialValue ;
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range [pin] = pwmRange ;
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newPin = pin ;
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res = piThreadCreate (softPwmThread) ;
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while (newPin != -1)
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delay (1) ;
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return res ;
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}
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@ -0,0 +1,27 @@
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/*
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* softPwm.h:
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* Provide 2 channels of software driven PWM.
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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
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* published by the Free Software Foundation, either version 3 of the
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* License, or (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
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* License along with wiringPi.
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* If not, see <http://www.gnu.org/licenses/>.
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***********************************************************************
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*/
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extern int setupSoftPwm (int pin) ;
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extern int softPwmCreate (int pin, int value, int range) ;
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extern void softPwmWrite (int pin, int value) ;
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