Build Instructions

Collapse

• 1

  Main Wiring

  Connect MPR121 to arudino i2c and power. On a Micro this is pins 2&3 plus VCC and GND. Flash the arduino and make sure everything works as you like. Breaking out the RST pin to a tactile switch is probably unnecessary, i've had no problem re-flashing the 'ino since it's been put together, but it's a good idea.

  /* Capacitive touch sensor gamepad
   *  Intended for use with Adafruit's breakout and library for the MPR121 capacitive
   *  sensor module and a USB-native Ardiuno (e.g. has a ATmega32U4).
   *  
   *  Much propers to Matthew Heironimus for his Joystick library. There are a bunch of 
   *  other libraries for the same purpose but i don't even care if they're better, his
   *  is far and away the best documented i've found.
   *  (https://github.com/MHeironimus/ArduinoJoystickLibrary/)
    */
  /* ELECTRODE MAP:
     11                 10
        7           0
      8   6       3   2
        9           1
            4   5
  MPR electrode #:  SNES equiv.:    associated Joystick.h control:
    0                   Y               b4
    1                   A               b1
    2                   B               b2
    3                   X               b3
    4                   select          b6
    5                   start           b7
    6                   D-right         x+
    7                   D-down          y-
    8                   D-left          x-
    9                   D-up            y+
    10                  Rb              b5
    11                  Lb              b4
    ((Without making it pretend to be XInput there probably has to be some kind
    of reassignation by the end-user.))
  */
  
  const uint8_t Nu=7;
  const uint8_t Nd=9;
  const uint8_t Nl=8;
  const uint8_t Nr=6;
  const uint8_t Na=1;
  const uint8_t Nb=2;
  const uint8_t Nx=3;
  const uint8_t Ny=0;
  const uint8_t Nrb=10;
  const uint8_t Nlb=11;
  const uint8_t Nst=5;
  const uint8_t Nse=4;
  const uint8_t padDelay = 10;  // i haven't noticed any difference with values 0~25, YMMV
  
  #include <Joystick.h>
  #include <Wire.h>;
  #include <Adafruit_MPR121.h>
  
  Adafruit_MPR121 cap = Adafruit_MPR121();
  Joystick_ pad(JOYSTICK_DEFAULT_REPORT_ID,JOYSTICK_TYPE_GAMEPAD,
    8, 0,                  // Button Count, Hat Switch Count
    true, true, false,     // X and Y, but no Z Axis
    false, false, false,   // No Rx, Ry, or Rz
    false, false,          // No rudder or throttle
    false, false, false);  // No accelerator, brake, or steering
  uint16_t padread;     // to hold inputs for processing
  
  int8_t yInertia = 0;  // for cleaning SCNODS, Simultaneous CardiNal Opposite Direction System
  int8_t xInertia = 0;
  
  
  void setup() {
    delay(10);
    cap.begin(0x5A);
    pad.begin(false); // "By default, all methods update the game controller state immediately." The whole rest of loop{} probably doesn't take as long as talking to the host 12 times. No, wait, prolly the library has delays built in
    pad.setXAxisRange(-1, 1);
    pad.setYAxisRange(-1, 1);  
  }
  
  void loop() {
    padread = cap.touched();
    
    // D-PAD:
    switch(((padread & (1<<Nu)) && (1<<Nu)) + ((padread & (1<<Nd)) && (1<<Nd))) {       // how many of up and down are pressed?
      case 0:                         // none? do nothing, forget everything
        pad.setYAxis(0);
        yInertia = 0;
        break;
      case 1:                         // just one?
        if ((padread & (1<<Nu)) && (1<<Nu)) {     // is it up? then go up
          pad.setYAxis(1);
          yInertia = 1;
        } else {                      // otherwise it's gotta be down, go down.
          pad.setYAxis(-1);
          yInertia = -1;
        }
        break;
      case 2:                         // both are pressed?
        if (yInertia == 0) {break;}   // were we standing still? keep standing still
        if (yInertia > 0) {           // if we were going up, keep going up
          pad.setYAxis(1);
          yInertia = 1;
        } else {                      // otherwise we must've been going down, go down
          pad.setYAxis(-1);
          yInertia = -1;
        }
    } // end y-axis, do the same for x-axis
    switch(((padread & (1<<Nl)) && (1<<Nl)) + ((padread & (1<<Nr)) && (1<<Nr))) {
      case 0:
        pad.setXAxis(0);
        xInertia = 0;
        break;
      case 1:
        if ((padread & (1<<Nr)) && (1<<Nr)) {
          pad.setXAxis(1);
          xInertia = 1;
        } else {
          pad.setXAxis(-1);
          xInertia = -1;
        }
        break;
      case 2:
        if (xInertia == 0) {break;}
        if (xInertia > 0) {
          pad.setXAxis(1);
          xInertia = 1;
        } else {
          pad.setXAxis(-1);
          xInertia = -1;
        }
    } // end of x-axis
    // END OF D-PAD
    
    // non-hysterical buttons:
    pad.setButton(0, ((padread & (1<<Na)) && (1<<Na))); // a
    pad.setButton(1, ((padread & (1<<Nb)) && (1<<Nb))); // b
    pad.setButton(2, ((padread & (1<<Nx)) && (1<<Nx))); // x
    pad.setButton(3, ((padread & (1<<Ny)) && (1<<Ny))); // y
    pad.setButton(4, ((padread & (1<<Nlb)) && (1<<Nlb))); // LB
    pad.setButton(5, ((padread & (1<<Nrb)) && (1<<Nrb))); // RB
    pad.setButton(6, ((padread & (1<<Nse)) && (1<<Nse))); // select/back
    pad.setButton(7, ((padread & (1<<Nst)) && (1<<Nst))); // start
    
    pad.sendState();
    delay(padDelay);
  }

• 2

  Build the front face

  Map out one piece of cardboard with placements for the screws

• 3

  Strain relief

  Cut a notch in a piece of plastic to hold the USB line from pulling out and cut a slot into the cardboard face to hold that. I could've just glued the arduino and the cable to the cardboard but this feels like a better solution.
  

View all 6 instructions