114 lines
2.8 KiB
C
114 lines
2.8 KiB
C
/*
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* piNes.c:
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* Driver for the NES Joystick controller on the Raspberry Pi
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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 <wiringPi.h>
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#include "piNes.h"
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#define MAX_NES_JOYSTICKS 8
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#define NES_RIGHT 0x01
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#define NES_LEFT 0x02
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#define NES_DOWN 0x04
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#define NES_UP 0x08
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#define NES_START 0x10
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#define NES_SELECT 0x20
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#define NES_B 0x40
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#define NES_A 0x80
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#define PULSE_TIME 25
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// Data to store the pins for each controller
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struct nesPinsStruct
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{
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unsigned int cPin, dPin, lPin ;
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} ;
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static struct nesPinsStruct nesPins [MAX_NES_JOYSTICKS] ;
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static int joysticks = 0 ;
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/*
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* setupNesJoystick:
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* Create a new NES joystick interface, program the pins, etc.
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*********************************************************************************
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*/
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int setupNesJoystick (int dPin, int cPin, int lPin)
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{
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if (joysticks == MAX_NES_JOYSTICKS)
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return -1 ;
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nesPins [joysticks].dPin = dPin ;
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nesPins [joysticks].cPin = cPin ;
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nesPins [joysticks].lPin = lPin ;
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digitalWrite (lPin, LOW) ;
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digitalWrite (cPin, LOW) ;
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pinMode (lPin, OUTPUT) ;
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pinMode (cPin, OUTPUT) ;
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pinMode (dPin, INPUT) ;
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return joysticks++ ;
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}
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/*
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* readNesJoystick:
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* Do a single scan of the NES Joystick.
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*********************************************************************************
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*/
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unsigned int readNesJoystick (int joystick)
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{
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unsigned int value = 0 ;
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int i ;
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struct nesPinsStruct *pins = &nesPins [joystick] ;
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// Toggle Latch - which presents the first bit
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digitalWrite (pins->lPin, HIGH) ; delayMicroseconds (PULSE_TIME) ;
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digitalWrite (pins->lPin, LOW) ; delayMicroseconds (PULSE_TIME) ;
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// Read first bit
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value = digitalRead (pins->dPin) ;
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// Now get the next 7 bits with the clock
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for (i = 0 ; i < 7 ; ++i)
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{
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digitalWrite (pins->cPin, HIGH) ; delayMicroseconds (PULSE_TIME) ;
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digitalWrite (pins->cPin, LOW) ; delayMicroseconds (PULSE_TIME) ;
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value = (value << 1) | digitalRead (pins->dPin) ;
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}
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return value ^ 0xFF ;
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}
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