daniel veilleux / SNESController

A simple class for reading button presses from a Super Nintendo (SNES) controller. Requires access to the controller's latch, clock, and data pins.

ABOUT

A simple class for reading a Super Nintendo (SNES) controller's buttons.

HARDWARE

The library was developed using the Nordic mKIT and cheap controllers.

NOTE: This controller has a wide VCC tolerance and continues to operate even when the mKIT is running off of a coin cell battery.

            +-----------+           
            |           |           
            |    +-+    |           
            |    +-+--------+VCC    
            |           |           
            |    +-+    |           
            |    +-+--------+CLOCK  
            |           |           
            |    +-+    |           
            |    +-+--------+LATCH  
            |           |           
            |    +-+    |           
            |    +-+--------+DATA   
            |           |           
            +-----------+           
            |           |           
            |    +-+    |           
            |    +-+--------+N/C    
            |           |           
            |    +-+    |           
            |    +-+--------+N/C    
            |           |           
            |    +-+    |           
            X    +-+----+---+GND    
             X         X            
              ---------             
                                    
          Controller pinout         
(looking into the female connector) 

USAGE

After wiring up a controller:

Include the library

#include "SNESController.h"

Create a new object and specify the pins

SNESController snes(P0_20, P0_21, P0_22);

Read and decode the button presses

uint16_t state = snes.read();
if (snes.pressed(state, SNESController::SNES_BUTTON_RIGHT_ARROW)) {
    ...
}

Poll the controller periodically

Ticker ticker;
ticker.attach(periodicCallback, 0.05);

SNESController.h

Committer:
foolsday
Date:
2015-01-14
Revision:
0:7deb78c1c738

File content as of revision 0:7deb78c1c738:

/* SNES Controller library
 * Copyright (c) 2015 Daniel Veilleux
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
 
 
#ifndef __SNES_CONTROLLER_H__
#define __SNES_CONTROLLER_H__

#include "mbed.h"


/**
* @class SNESController
* @brief Reads the state of an SNES controller and decodes the button presses.
*/
class SNESController {
public:

    /**
     * @enum SNESButton_t
     * @brief The masks of the individual buttons as read from the controller
     */
    enum SNESButton_t
    {
        SNES_BUTTON_B           = 0x0001,
        SNES_BUTTON_Y           = 0x0002,
        SNES_BUTTON_SEL         = 0x0004,
        SNES_BUTTON_START       = 0x0008,
        SNES_BUTTON_UP_ARROW    = 0x0010,
        SNES_BUTTON_DOWN_ARROW  = 0x0020,
        SNES_BUTTON_LEFT_ARROW  = 0x0040,
        SNES_BUTTON_RIGHT_ARROW = 0x0080,
        SNES_BUTTON_A           = 0x0100,
        SNES_BUTTON_X           = 0x0200,
        SNES_BUTTON_L           = 0x0400,
        SNES_BUTTON_R           = 0x0800
    };


    /**
     * @brief Constructs a new object for reading button presses
     *
     * @param  latch
     *         A PinName specifying the latch pin (pin #3)
     * @param  clock
     *         A PinName specifying the clock pin (pin #2)
     * @param  data
     *         A PinName specifying the data pin (pin #4)
     *
     */
    SNESController(PinName latch, PinName clock, PinName data):
        latchPin(latch),
        clockPin(clock),
        dataPin(data) {
            latchPin = 0;
            clockPin = 1;
        }


    /**
     * @brief Reads the current state of the controller and returns a button mask
     *
     * @return
     *     A 16-bit mask containing the states of all of the buttons.
     *     Pressed buttons will have their bits set to 1.
     */
    uint16_t read(void)
    {
        uint32_t mask;
        uint16_t buttons = 0;

        latchPin = 1;
        wait_us(12);
        latchPin = 0;

        wait_us(6);

        for (mask = 0x0001; mask < 0x10000; mask <<= 1)
        {
            clockPin = 0;
            wait_us(6);
    
            // Data is active low.
            if (!dataPin)
            {
                buttons |= mask;
            }

            clockPin = 1;
            wait_us(6);
        }

        return buttons;
    }


    /**
     * @brief Returns true if the specified button is pressed in the given buttonMask
     *
     * @return
     *     True if the specified button is pressed in the mask
     */
    __inline bool pressed(uint16_t buttonMask, SNESButton_t button)
    {
        return (buttonMask & button);    
    }


private:
    DigitalOut latchPin;
    DigitalOut clockPin;
    DigitalIn dataPin;
};

#endif /* #ifndef __SNES_CONTROLLER_H__*/