qmk_firmware/quantum/process_keycode/process_joystick.c

#include "process_joystick.h"

#include <quantum/joystick.h>
#include <quantum/quantum_keycodes.h>

#ifdef __AVR__
# include <drivers/avr/analog.h>
#endif

#include <string.h>

bool process_joystick_buttons(uint16_t keycode, keyrecord_t *record);

bool process_joystick(uint16_t keycode, keyrecord_t *record){
  
  if (process_joystick_buttons(keycode, record) 
    && (joystick_status.status & JS_UPDATED)>0){
    send_joystick_packet(&joystick_status);
    joystick_status.status &= ~JS_UPDATED;
  }
  
  return true;
}

__attribute__ ((weak))
void joystick_task(void){
  if (process_joystick_analogread() && (joystick_status.status & JS_UPDATED)){
    send_joystick_packet(&joystick_status);
    joystick_status.status &= ~JS_UPDATED;
  }
}



bool process_joystick_buttons(uint16_t keycode, keyrecord_t *record){
  
  if (keycode < JS_BUTTON0 || keycode > JS_BUTTON_MAX){
    return true;
  } else {
    if (record->event.pressed){
      joystick_status.buttons[(keycode-JS_BUTTON0)/8] |= 1<<(keycode%8);
    } else {
      joystick_status.buttons[(keycode-JS_BUTTON0)/8] &= ~(1<<(keycode%8));
    }
    
    joystick_status.status |= JS_UPDATED;
  }
  
  return true;
}

uint8_t savePinState(uint8_t pin){
#ifdef __AVR__
  uint8_t pinNumber = pin & 0xF;
  return ((PIN_ADDRESS(pin, 2) >> pinNumber) & 0x1) << 1 
       | ((PIN_ADDRESS(pin, 1) >> pinNumber) & 0x1) ;
#else
  return 0;
#endif
}

void restorePinState(uint8_t pin, uint8_t restoreState){
#ifdef __AVR__
  uint8_t pinNumber = pin & 0xF;
  PIN_ADDRESS(pin, 2) = (PIN_ADDRESS(pin, 2) & ~_BV(pinNumber)) | (((restoreState >> 1) & 0x1) << pinNumber);
  PIN_ADDRESS(pin, 1) = (PIN_ADDRESS(pin, 1) & ~_BV(pinNumber)) | ((restoreState & 0x1) << pinNumber);
#else
  return;
#endif
}

__attribute__ ((weak))
bool process_joystick_analogread(){
  return process_joystick_analogread_quantum();
}

bool process_joystick_analogread_quantum(){

#if JOYSTICK_AXES_COUNT > 0
  for (int axis_index=0 ; axis_index<JOYSTICK_AXES_COUNT ; ++axis_index){
    if (joystick_axes[axis_index].input_pin==JS_VIRTUAL_AXIS){
      continue;
    }
    
    //save previous input pin status as well
    uint8_t inputSavedState = savePinState(joystick_axes[axis_index].input_pin);
    
    //disable pull-up resistor
    writePinLow(joystick_axes[axis_index].input_pin);
    
    //if pin was a pull-up input, we need to uncharge it by turning it low 
    // before making it a low input
    setPinOutput(joystick_axes[axis_index].input_pin);
    
    wait_us(10);
    
    //save and apply output pin status
    uint8_t outputSavedState = 0;
    if (joystick_axes[axis_index].output_pin!=JS_VIRTUAL_AXIS) {
      //save previous output pin status
      outputSavedState = savePinState(joystick_axes[axis_index].output_pin);
      
      setPinOutput(joystick_axes[axis_index].output_pin);
      writePinHigh(joystick_axes[axis_index].output_pin);
    }
    
    uint8_t groundSavedState = 0;
    if (joystick_axes[axis_index].ground_pin!=JS_VIRTUAL_AXIS) {
      //save previous output pin status
      groundSavedState = savePinState(joystick_axes[axis_index].ground_pin);
      
      setPinOutput(joystick_axes[axis_index].ground_pin);
      writePinLow(joystick_axes[axis_index].ground_pin);
    }
    
    wait_us(10);
    
    setPinInput(joystick_axes[axis_index].input_pin);
    
    wait_us(10);
    
#ifdef __AVR__
    int16_t axis_val = analogReadPin(joystick_axes[axis_index].input_pin);
#else
  //default to resting position
    int16_t axis_val = joystick_axes[axis_index].mid_digit;
#endif
    
    //test the converted value against the lower range
    uint16_t ref = joystick_axes[axis_index].mid_digit;
    uint16_t range = joystick_axes[axis_index].min_digit;
    int16_t ranged_val = -127*fminf(1.f, (axis_val - (float)(ref)) /(range - (float)ref));
    if (ranged_val > 0){
      //the value is in the higher range
      range = joystick_axes[axis_index].max_digit;
      ranged_val = 127*fminf(1.f, (axis_val - (float)(ref)) /(range - (float)ref));
    }
    
    if (ranged_val!=joystick_status.axes[axis_index]){
      joystick_status.axes[axis_index] = ranged_val;
      joystick_status.status |= JS_UPDATED;
    }
    
    //restore output, ground and input status
    if (joystick_axes[axis_index].output_pin!=JS_VIRTUAL_AXIS) {
      restorePinState(joystick_axes[axis_index].output_pin, outputSavedState);
    }
    if (joystick_axes[axis_index].ground_pin!=JS_VIRTUAL_AXIS) {
      restorePinState(joystick_axes[axis_index].ground_pin, groundSavedState);
    }
    
    restorePinState(joystick_axes[axis_index].input_pin, inputSavedState);
    
  }
  
#endif
  return true;
}