Adapt Teensy code to Mega

Development Boards Arduino
1

I need to adapt the following code, written for a Teensy 2.0 (from here http://forum.il2sturmovik.com/topic/179 … entry46472 ), to run on a Mega:

/* USB FLCS Grip
   You must select Joystick from the "Tools > USB Type" menu
*/

// Buttons are muxed into shift registers, use the SPI protocol to read them
#include <SPI.h>

const int slaveSelectPin = 0;

unsigned int buttonInputs1;   // data read from SPI
unsigned int buttonInputs2;
unsigned int buttonInputs3;

// Use some macros to clean things up
#define S3   !(buttonInputs1 & 0x80)    /* Pinky Switch */
#define TG1  !(buttonInputs1 & 0x40)    /* Trigger 1 */
#define TG2  !(buttonInputs1 & 0x20)    /* Trigger 2 */
#define S1   !(buttonInputs1 & 0x10)    /* Nose Wheel Steering */
#define S4   !(buttonInputs1 & 0x08)    /* Paddle Switch */
#define S2   !(buttonInputs1 & 0x04)    /* Pickle */

#define H1D  !(buttonInputs2 & 0x80)    /* Trim */
#define H1R  !(buttonInputs2 & 0x40)
#define H1U  !(buttonInputs2 & 0x20)
#define H1L  !(buttonInputs2 & 0x10)
#define H4U  !(buttonInputs2 & 0x08)    /* CMS */
#define H4L  !(buttonInputs2 & 0x04)
#define H4D  !(buttonInputs2 & 0x02)
#define H4R  !(buttonInputs2 & 0x01)

#define H3D  !(buttonInputs3 & 0x80)    /* DMS */
#define H3R  !(buttonInputs3 & 0x40)
#define H3U  !(buttonInputs3 & 0x20)
#define H3L  !(buttonInputs3 & 0x10)
#define H2D  !(buttonInputs3 & 0x08)    /* TMS */
#define H2R  !(buttonInputs3 & 0x04)
#define H2U  !(buttonInputs3 & 0x02)
#define H2L  !(buttonInputs3 & 0x01)

// setup() runs once on boot
void setup() {
  // set the slaveSelectPin as an output:
  pinMode (slaveSelectPin, OUTPUT);
  // start the SPI library:
  SPI.begin();
  // configure the joystick to manual send mode.  This gives precise
  // control over when the computer receives updates, but it does
  // require you to manually call Joystick.send_now().
  Joystick.useManualSend(true);
}


// loop() runs for as long as power is applied
void loop() {
  // take the SS pin low to select the chip
  digitalWrite(slaveSelectPin,LOW);
  // send a value of 0 to read the SPI bytes
  buttonInputs1 = SPI.transfer(0x00);
  buttonInputs2 = SPI.transfer(0x00);
  buttonInputs3 = SPI.transfer(0x00);
  // take the SS pin high to de-select the chip:
  digitalWrite(slaveSelectPin,HIGH); 

  // Write to joystick buttons
  Joystick.button(1,  TG1);
  Joystick.button(2,  S2);
  Joystick.button(3,  S3);
  Joystick.button(4,  S4);
  Joystick.button(5,  S1);
  Joystick.button(6,  TG2);
  Joystick.button(7,  H2U);
  Joystick.button(8,  H2R);
  Joystick.button(9,  H2D);
  Joystick.button(10, H2L);
  Joystick.button(11, H3U);
  Joystick.button(12, H3R);
  Joystick.button(13, H3D);
  Joystick.button(14, H3L);
  Joystick.button(15, H4U);
  Joystick.button(16, H4R);
  Joystick.button(17, H4D);
  Joystick.button(18, H4L);
  //Joystick.button(19, H1U);
  //Joystick.button(20, H1R);
  //Joystick.button(21, H1D);
  //Joystick.button(22, H1L);
  
  // Determine Joystick Hat Position
  int angle = -1;

  if (H1U) {
    if (H1R) {
      angle = 45;
    } else if (H1L) {
      angle = 315;
    } else {
      angle = 0;
    }
  } else if (H1D) {
    if (H1R) {
      angle = 135;
    } else if (H1L) {
      angle = 225;
    } else {
      angle = 180;
    }
  } else if (H1R) {
    angle = 90;
  } else if (H1L) {
    angle = 270;
  }
  Joystick.hat(angle);
  
  // Because setup configured the Joystick manual send,
  // the computer does not see any of the changes yet.
  // This send_now() transmits everything all at once.
  Joystick.send_now();
}

Comparing the pinouts of the Teensy 2.0 https://www.pjrc.com/teensy/pinout.html and the Mega http://arduino.cc/en/Main/arduinoBoardMega , I can see the latter uses pins 50-53 for the SPI (MISO, MOSI, SCK, SS), whereas the Teensy uses Pins 0-3 (SS, SCLK, MOSI, MISO).

The only pin assignment I can see in the code is for SS:

const int slaveSelectPin = 0;

so do I just need to change this to

const int slaveSelectPin = 53;

for the Mega? I guess it’s going to need some more code to run as a USB Joystick, as Arduino IDE doesn’t have “Tools > USB Type” to set to “Joystick”, so can anyone help out with that as well please? Alternatively, I could just run it as a USB Serial device (i.e. on a COM port) or via an Ethernet Shield and use some bridge software on the PC to convert the data into something suitable for my flight sims but I need an easy way to test that the joystick buttons/hats are sending signals before I get to that stage, maybe using the Serial Monitor?

2

It occurred to me I might be able to use a spare Pro Micro I have instead of wasting a Mega on this but looking at the pinout, it doesn’t appear to have a SS pin, so is this not possible?