FPV гонки на симуляторе (делаем USB джойстик из пульта радиоуправления)

— , FPV , , , - .

, . , PPM USB-, . , . , ? :

-, , FPV Freerider, Phoenix RC Aerofly RC 7. FPV Freerider - , -.

— !

:

- RC- , PPM (Pulse Position Modulation) . PPM-c , .
PPM :


PPM ( : , ).

:

AlexeyStn PPM-to-USB STM32F3Discovery, Arduino Pro Micro (Leonardo) USB, .

, USB . , . rc-leonardo-joy, , : — . , , !

, : PPM micros():

void rxInt(void) {
  uint16_t now,diff;
  static uint16_t last = 0;
  static uint8_t chan = 0;

  now = micros();
  sei();
  diff = now - last;
  last = now;
  if(diff>3000) chan = 0;
  else {
    if(900<diff && diff<2200 && chan<RC_CHANS ) {
      rcValue[chan] = adjust(diff,chan);
    }
    chan++;
  }
}

micros() Arduino:

Returns the number of microseconds since the Arduino board began running the current program. This number will overflow (go back to zero), after approximately 70 minutes. On 16 MHz Arduino boards (e.g. Duemilanove and Nano), this function has a resolution of four microseconds (i.e. the value returned is always a multiple of four). On 8 MHz Arduino boards (e.g. the LilyPad), this function has a resolution of eight microseconds.

, 4 , 70 , - . . .

: (0-255):

// Convert a value in the range 1000-2000 to 0-255
byte stickValue(int rcVal) {
  return map( constrain(rcVal - 1000, 0, 1000), 0, 1000, 0, 255);
}

, . HID .

— !
, PPM :

void initTimer(void) { 
	// Input Capture setup
	// ICNC1: =0 Disable Input Capture Noise Canceler to prevent delay in reading
	// ICES1: =1 for trigger on rising edge
	// CS11: =1 set prescaler to 1/8 system clock (F_CPU)
	TCCR1A = 0;
	TCCR1B = (0<<ICNC1) | (1<<ICES1) | (1<<CS11);
	TCCR1C = 0;

	// Interrupt setup
	// ICIE1: Input capture 
	TIFR1 = (1<<ICF1); // clear pending
	TIMSK1 = (1<<ICIE1); // and enable
}
...

ISR(TIMER1_CAPT_vect) {
	union twoBytes {
		uint16_t word;
		uint8_t  byte[2];
	} timeValue;

	uint16_t now, diff;
	static uint16_t last = 0;
	static uint8_t chan = 0;
	
	timeValue.byte[0] = ICR1L;    // grab captured timer value (low byte)
	timeValue.byte[1] = ICR1H;    // grab captured timer value (high byte)

	now = timeValue.word;
	diff = now - last;
	last = now;

	//all numbers are microseconds multiplied by TIMER_COUNT_DIVIDER (as prescaler is set to 1/8 of 16 MHz)
	if(diff > (NEWFRAME_PULSE_WIDTH * TIMER_COUNT_DIVIDER)) {
		chan = 0;  // new data frame detected, start again
	}
	else {
		if(diff > (MIN_PULSE_WIDTH * TIMER_COUNT_DIVIDER - THRESHOLD) 
			&& diff < (MAX_PULSE_WIDTH * TIMER_COUNT_DIVIDER + THRESHOLD) 
			&& chan < RC_CHANNELS_COUNT) 
		{
			rcValue[chan] = adjust(diff, chan); //store detected value
		}
		chan++; //no value detected within expected range, move to next channel
	}
}

0-1000 HID descriptor:

	// Joystick
	0x05, 0x01,			// USAGE_PAGE (Generic Desktop)
	0x09, 0x04,			// USAGE (Joystick)
	0xa1, 0x01,			// COLLECTION (Application)
	0x85, JOYSTICK_REPORT_ID,	//   REPORT_ID (3)
	...
	0xA1, 0x00,		    //   COLLECTION (Physical)
	0x09, 0x30,		    //     USAGE (x)
	0x09, 0x31,		    //     USAGE (y)
	0x09, 0x33,		    //     USAGE (rx)
	0x09, 0x34,		    //     USAGE (ry)
	0x15, 0x00,		    //	   LOGICAL_MINIMUM (0)
	0x26, 0xE8, 0x03,	    //     LOGICAL_MAXIMUM (1000)
	0x75, 0x10,	  	    //	   REPORT_SIZE (16)
	0x95, 0x04,		    //     REPORT_COUNT (4)
	0x81, 0x02,		    //     INPUT (Data,Var,Abs)
	0xc0,			    //   END_COLLECTION

	0xc0				// END_COLLECTION

uint8_t uint16_t .
, #define , PPM-USB.

: github.com/voroshkov/Leonardo-USB-RC-Adapter

:

, :

#define FUTABA

- , :

#define STICK_HALFWAY 500
#define STICK_CENTER 1500
#define THRESHOLD 100

:

, USB Arduino, .
Arduino ...\Arduino\hardware\arduino\cores\arduino\, usbapi.h hid.cpp, ArduinoLibs . , Arduino Leonardo .

:

: USB, c – ( Digital Pin 4 ) PPM . - :

Windows 7 (, , ) Arduino Leonardo.

. - -, - ( Futaba 7C) – :


«»- . «» , , , , , . , , , . , :

( 4 , .)

. , , .

P.S.

Arduino Leonardo, Minimum Development Board STM32F103C8T6?

, . , , .
: github.com/voroshkov/STM32-RC-USB-Adapter.

.

!