mirror of
https://github.com/clockworkpi/WiringPi.git
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25e4ec570b
delayMicrosecondsHard re-written - again. Added a serialRead example program, and added in the okLed to the examples too. Updated/checked some of the GPIO/PWM code. Added in some experimental servo and tone generating code and and example or 2. Tweaks to the gpio command to correctly load the I2C modules too.
120 lines
2.6 KiB
C
120 lines
2.6 KiB
C
/*
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* softTone.c:
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* For that authentic retro sound...
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* Er... A little experiment to produce tones out of a Pi using
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* one (or 2) GPIO pins and a piezeo "speaker" element.
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* (Or a high impedance speaker, but don'y blame me if you blow-up
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* the GPIO pins!)
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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 "softTone.h"
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#define MAX_PINS 64
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#define PULSE_TIME 100
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static int frewqs [MAX_PINS] ;
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static int newPin = -1 ;
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/*
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* softToneThread:
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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 (softToneThread)
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{
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int pin, frewq, halfPeriod ;
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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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frewq = frewqs [pin] ;
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if (frewq != 0)
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{
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halfPeriod = 500000 / frewq ;
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digitalWrite (pin, HIGH) ;
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delayMicroseconds (halfPeriod) ;
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digitalWrite (pin, LOW) ;
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delayMicroseconds (halfPeriod) ;
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}
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}
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return NULL ;
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}
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/*
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* softToneWrite:
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* Write a frequency value to the given pin
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*********************************************************************************
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*/
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void softToneWrite (int pin, int frewq)
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{
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pin &= 63 ;
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/**/ if (frewq < 0)
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frewq = 0 ;
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else if (frewq > 5000) // Max 5KHz
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frewq = 5000 ;
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frewqs [pin] = frewq ;
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}
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/*
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* softToneCreate:
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* Create a new tone thread.
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*********************************************************************************
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*/
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int softToneCreate (int pin)
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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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frewqs [pin] = 0 ;
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newPin = pin ;
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res = piThreadCreate (softToneThread) ;
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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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