Subversion Repositories FlightCtrl

#include <stdlib.h>
#include <avr/io.h>
#include <avr/interrupt.h>

#include "rc.h"
#include "controlMixer.h"
#include "configuration.h"
#include "commands.h"
#include "output.h"

// The channel array is 0-based!
volatile int16_t PPM_in[MAX_CHANNELS];
volatile uint8_t RCQuality;

uint8_t lastRCCommand = COMMAND_NONE;
uint8_t lastFlightMode = FLIGHT_MODE_NONE;

/***************************************************************
 *  16bit timer 1 is used to decode the PPM-Signal            
 ***************************************************************/
void RC_Init(void) {
  uint8_t sreg = SREG;

  // disable all interrupts before reconfiguration
  cli();

  // PPM-signal is connected to the Input Capture Pin (PD6) of timer 1
  DDRD &= ~(1<<6);
  PORTD |= (1<<PORTD6);

  // Channel 5,6,7 is decoded to servo signals at pin PD5 (J3), PD4(J4), PD3(J5)
  // set as output
  DDRD |= (1<<DDD5) | (1<<DDD4) | (1<<DDD3);
  // low level
  PORTD &= ~((1<<PORTD5) | (1<<PORTD4) | (1<<PORTD3));

  // PD3 can't be used if 2nd UART is activated
  // because TXD1 is at that port
  if (CPUType != ATMEGA644P) {
    DDRD |= (1<<PORTD3);
    PORTD &= ~(1<<PORTD3);
  }

  // Timer/Counter1 Control Register A, B, C

  // Normal Mode (bits: WGM13=0, WGM12=0, WGM11=0, WGM10=0)
  // Compare output pin A & B is disabled (bits: COM1A1=0, COM1A0=0, COM1B1=0, COM1B0=0)
  // Set clock source to SYSCLK/64 (bit: CS12=0, CS11=1, CS10=1)
  // Enable input capture noise cancler (bit: ICNC1=1)
  // Trigger on positive edge of the input capture pin (bit: ICES1=1),
  // Therefore the counter incremets at a clock of 20 MHz/64 = 312.5 kHz or 3.2�s
  // The longest period is 0xFFFF / 312.5 kHz = 0.209712 s.
  TCCR1A &= ~((1 << COM1A1) | (1 << COM1A0) | (1 << COM1B1) | (1 << COM1B0) | (1 << WGM11) | (1 << WGM10));
  TCCR1B &= ~((1 << WGM13) | (1 << WGM12) | (1 << CS12));
  TCCR1B |= (1 << CS11) | (1 << CS10) | (1 << ICES1) | (1 << ICNC1);
  TCCR1C &= ~((1 << FOC1A) | (1 << FOC1B));

  // Timer/Counter1 Interrupt Mask Register
  // Enable Input Capture Interrupt (bit: ICIE1=1)
  // Disable Output Compare A & B Match Interrupts (bit: OCIE1B=0, OICIE1A=0)
  // Enable Overflow Interrupt (bit: TOIE1=0)
  TIMSK1 &= ~((1<<OCIE1B) | (1<<OCIE1A) | (1<<TOIE1));
  TIMSK1 |= (1<<ICIE1);

  RCQuality = 0;

  SREG = sreg;
}

/********************************************************************/
/*         Every time a positive edge is detected at PD6            */
/********************************************************************/
/*                               t-Frame
    <----------------------------------------------------------------------->
     ____   ______   _____   ________                ______    sync gap      ____
    |    | |      | |     | |        |              |      |                |
    |    | |      | |     | |        |              |      |                |
 ___|    |_|      |_|     |_|        |_.............|      |________________|
    <-----><-------><------><-----------            <------>                <---
 t0       t1      t2       t4                     tn                     t0

 The PPM-Frame length is 22.5 ms.
 Channel high pulse width range is 0.7 ms to 1.7 ms completed by an 0.3 ms low pulse.
 The mininimum time delay of two events coding a channel is ( 0.7 + 0.3) ms = 1 ms.
 The maximum time delay of two events coding a channel is ( 1.7 + 0.3) ms = 2 ms.
 The minimum duration of all channels at minimum value is  8 * 1 ms = 8 ms.
 The maximum duration of all channels at maximum value is  8 * 2 ms = 16 ms.
 The remaining time of (22.5 - 8 ms) ms = 14.5 ms  to (22.5 - 16 ms) ms = 6.5 ms is
 the syncronization gap.
 */
ISR(TIMER1_CAPT_vect) { // typical rate of 1 ms to 2 ms
  int16_t signal, tmp;
  static int16_t index;
  static uint16_t oldICR1 = 0;

  // 16bit Input Capture Register ICR1 contains the timer value TCNT1
  // at the time the edge was detected

  // calculate the time delay to the previous event time which is stored in oldICR1
  // calculatiing the difference of the two uint16_t and converting the result to an int16_t
  // implicit handles a timer overflow 65535 -> 0 the right way.
  signal = (uint16_t) ICR1 - oldICR1;
  oldICR1 = ICR1;

  //sync gap? (3.52 ms < signal < 25.6 ms)
  if ((signal > 1100) && (signal < 8000)) {
    index = 0;
  } else { // within the PPM frame
    if (index < MAX_CHANNELS) { // PPM24 supports 12 channels
      // check for valid signal length (0.8 ms < signal < 2.1984 ms)
      // signal range is from 1.0ms/3.2us = 312 to 2.0ms/3.2us = 625
      if ((signal > 250) && (signal < 687)) {
        // shift signal to zero symmetric range  -154 to 159
        signal -= 475; // offset of 1.4912 ms ??? (469 * 3.2us = 1.5008 ms)
        // check for stable signal
        if (abs(signal - PPM_in[index]) < 6) {
          if (RCQuality < 200)
            RCQuality += 10;
          else
            RCQuality = 200;
        }
        // If signal is the same as before +/- 1, just keep it there. Naah lets get rid of this slimy sticy stuff.
        // if (signal >= PPM_in[index] - 1 && signal <= PPM_in[index] + 1) {
          // In addition, if the signal is very close to 0, just set it to 0.
        if (signal >= -1 && signal <= 1) {
          tmp = 0;
        //} else {
        //  tmp = PPM_in[index];
        //  }
        } else
          tmp = signal;
        PPM_in[index] = tmp; // update channel value
      }
      index++; // next channel
      // demux sum signal for channels 5 to 7 to J3, J4, J5
      // TODO: General configurability of this R/C channel forwarding. Or remove it completely - the
      // channels are usually available at the receiver anyway.
      // if(index == 5) J3HIGH; else J3LOW;
      // if(index == 6) J4HIGH; else J4LOW;
      // if(CPUType != ATMEGA644P) // not used as TXD1
      //  {
      //    if(index == 7) J5HIGH; else J5LOW;
      //  }
    }
  }
}

#define RCChannel(dimension) PPM_in[channelMap.channels[dimension]]
#define COMMAND_THRESHOLD 85
#define COMMAND_CHANNEL_VERTICAL CH_THROTTLE
#define COMMAND_CHANNEL_HORIZONTAL CH_YAW

#define RC_SCALING 4

uint8_t getControlModeSwitch(void) {
        int16_t channel = RCChannel(CH_MODESWITCH) + POT_OFFSET;
        uint8_t flightMode = channel < 256/3 ? FLIGHT_MODE_MANUAL :
                (channel > 256*2/3 ? FLIGHT_MODE_ANGLES : FLIGHT_MODE_RATE);
        return flightMode;
}

// Gyro calibration is performed as.... well mode switch with no throttle and no airspeed would be nice.
// Maybe simply: Very very low throttle.
// Throttle xlow for COMMAND_TIMER: GYROCAL (once).
// mode switched: CHMOD

uint8_t RC_getCommand(void) {
        uint8_t flightMode = getControlModeSwitch();

        if (lastFlightMode != flightMode) {
                lastFlightMode = flightMode;
                lastRCCommand = COMMAND_CHMOD;
                return lastRCCommand;
        }

        int16_t channel = RCChannel(CH_THROTTLE);

        if (channel <= -140) { // <= 900 us
                lastRCCommand = COMMAND_GYROCAL;
        } else {
          lastRCCommand = COMMAND_NONE;
        }
        return lastRCCommand;
}

uint8_t RC_getArgument(void) {
        return lastFlightMode;
}

/*
 * Get Pitch, Roll, Throttle, Yaw values
 */
void RC_periodicTaskAndPRYT(int16_t* PRYT) {
  if (RCQuality) {
    RCQuality--;

    debugOut.analog[20] = RCChannel(CH_ELEVATOR);
    debugOut.analog[21] = RCChannel(CH_AILERONS);
    debugOut.analog[22] = RCChannel(CH_RUDDER);
    debugOut.analog[23] = RCChannel(CH_THROTTLE);

    PRYT[CONTROL_ELEVATOR]   = RCChannel(CH_ELEVATOR) * RC_SCALING;
    PRYT[CONTROL_AILERONS]   = RCChannel(CH_AILERONS) * RC_SCALING;
    PRYT[CONTROL_RUDDER]     = RCChannel(CH_RUDDER)   * RC_SCALING;
    PRYT[CONTROL_THROTTLE]   = RCChannel(CH_THROTTLE) * RC_SCALING;
  } // if RCQuality is no good, we just do nothing.
}

/*
 * Get other channel value
 */
int16_t RC_getVariable(uint8_t varNum) {
  if (varNum < 4)
    // 0th variable is 5th channel (1-based) etc.
    return RCChannel(varNum + CH_POTS) + POT_OFFSET;
  /*
   * Let's just say:
   * The RC variable i is hardwired to channel i, i>=4
   */
  return PPM_in[varNum] + POT_OFFSET;
}

uint8_t RC_getSignalQuality(void) {
  if (RCQuality >= 160)
    return SIGNAL_GOOD;
  if (RCQuality >= 140)
    return SIGNAL_OK;
  if (RCQuality >= 120)
    return SIGNAL_BAD;
  return SIGNAL_LOST;
}

/*
 * To should fired only when the right stick is in the center position.
 * This will cause the value of pitch and roll stick to be adjusted
 * to zero (not just to near zero, as per the assumption in rc.c
 * about the rc signal. I had values about 50..70 with a Futaba
 * R617 receiver.) This calibration is not strictly necessary, but
 * for control logic that depends on the exact (non)center position
 * of a stick, it may be useful.
 */
void RC_calibrate(void) {
  // Do nothing.
}