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113 lines
2.8 KiB
113 lines
2.8 KiB
/* |
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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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