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// ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

// + Copyright (c) 04.2007 Holger Buss

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#include <stdlib.h>

#include <avr/io.h>

#include <avr/interrupt.h>

#include "rc.h"

#include "configuration.h"

volatile int16_t PPM_in[15]; //PPM24 supports 12 channels per frame

volatile int16_t PPM_diff[15];

volatile uint8_t NewPpmData = 1;

volatile int16_t RC_Quality = 0;

int16_t stickOffsetPitch = 0, stickOffsetRoll = 0;

/***************************************************************/

/*  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<<DDD6);

        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);

        // low level

        PORTD &= ~(/*(1<<PORTD5)|*/(1<<PORTD4));

        // 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 3.2µs

    // 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);

    RC_Quality = 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 chanel 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 = 0, 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))

    {

      // if a sync gap happens and there where at least 4 channels decoded before

      // then the NewPpmData flag is reset indicating valid data in the PPM_in[] array.

      if(index >= 4)

        {

          NewPpmData = 0;  // Null means NewData for the first 4 channels

        }

      // synchronize channel index

      index = 1;

    }

  else // within the PPM frame

    {

      if(index < 14) // 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 -= 466; // offset of 1.4912 ms ??? (469 * 3.2µs = 1.5008 ms)

              // check for stable signal

              if(abs(signal - PPM_in[index]) < 6) {

                if(RC_Quality < 200) RC_Quality +=10;

                else RC_Quality = 200;

              }

              // calculate exponential history for signal

              tmp = (3 * (PPM_in[index]) + signal) / 4;

              if(tmp > signal+1) tmp--; else

                if(tmp < signal-1) tmp++;

              // calculate signal difference on good signal level

              if(RC_Quality >= 195)  PPM_diff[index] = ((tmp - PPM_in[index]) / 3) * 3; // cut off lower 3 bit for nois reduction

              else PPM_diff[index] = 0;

              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[ParamSet.ChannelAssignment[dimension]] * ParamSet.StickP)

#define RCDiff(dimension) (PPM_diff[ParamSet.ChannelAssignment[dimension]] * ParamSet.StickD)

// To start with, we don't attempt to normalize.

//#define rc_normalize(stick) (stick * STICK_RANGE / NORMAL_RANGE_COUNTS)

#define RCNormalize(stick) stick

/* Get the pitch input in the nominal range [-STICK_RANGE, STICK_RANGE]. */

int16_t RC_getPitch (void) {

  return RCNormalize(RCChannel(CH_PITCH) - stickOffsetPitch + RCDiff(CH_PITCH));

}

/* Get the roll input in the nominal range [-STICK_RANGE, STICK_RANGE]. */

int16_t RC_getRoll (void) {

  return RCNormalize(RCChannel(CH_ROLL) - stickOffsetRoll + RCDiff(CH_ROLL));

}

/* Get the yaw input in the nominal range [-STICK_RANGE, STICK_RANGE]. */

int16_t RC_getYaw (void) {

  return RCNormalize(RCChannel(CH_YAW) + RCDiff(CH_YAW));

}

/* Get the throttle input in the nominal range [0, THROTTLE_RANGE]. */

uint16_t RC_getThrottle(void) {

// TODO: Some D term would actually be nice - at least for my acro style.

  // return (RcChannel(CH_THROTTLE) + NORMAL_RANGE_COUNTS) * THROTTLE_RANGE / MILLISECOND_COUNTS_1;

  return RcChannel(CH_THROTTLE);

}

uint16_t RC_getVariable(uint8_t channel) {

  return RCChannel(CH_POTS + channel) + POT_OFFSET;

}

uint8_t RC_getSignalQuality(void) {

  if (RC_Quality >= 160)

    return SIGNAL_EXCELLENT;

  if (RC_Quality >= 140)

    return SIGNAL_OK;

  if (RC_Quality >= 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) {

  stickOffsetPitch += stickPitch;

  stickOffsetRoll += stickRoll;

}

#define COMMAND_THRESHOLD 85

uint8_t RC_getCommand(void) {

  if(RCChannel(CH_THROTTLE) > COMMAND_THRESHOLD) {

    // throttle is up

    if(RCChannel(CH_YAW) > COMMAND_THRESHOLD)

      return STICK_COMMAND_GYROCAL;

    if(RCChannel(CH_YAW) < -COMMAND_THRESHOLD)

      return STICK_COMMAND_ACCCAL;

    return STICK_COMMAND_UNDEF;

  } else if(RCChannel(CH_THROTTLE) < -COMMAND_THRESHOLD) {

    // pitch is down

    if(RCChannel(CH_YAW) > COMMAND_THRESHOLD)

      return STICK_COMMAND_STOP;

    if(RCChannel(CH_YAW) < -COMMAND_THRESHOLD)

      return STICK_COMMAND_START;

    return STICK_COMMAND_UNDEF;

  } else {

    // pitch is around center

    return STICK_COMMAND_UNDEF;

  }

}

/*

 * Command arguments on R/C:

 * 2--3--4

 * |     |  +

 * 1  9  5  ^ 0

 * |     |  |  

 * 8--7--6

 *    

 * + <--

 *    0

 *

 * Not in any of these positions: 0

 */

#define ARGUMENT_THRESHOLD 70

uint8_t RC_getArgument(void) {

  if(RCChannel(CH_PITCH) > ARGUMENT_THRESHOLD) {

    // pitch is up

    if(RCChannel(CH_ROLL) > ARGUMENT_THRESHOLD)

      return 2;

    if(RCChannel(CH_ROLL) < -ARGUMENT_THRESHOLD)

      return 4;

    return 3;

  } else if(RCChannel(CH_PITCH) < -ARGUMENT_THRESHOLD) {

    // pitch is down

    if(RCChannel(CH_ROLL) > ARGUMENT_THRESHOLD)

      return 8;

    if(RCChannel(CH_ROLL) < -ARGUMENT_THRESHOLD)

      return 6;

    return 7;

  } else {

    // pitch is around center

    if(RCChannel(CH_ROLL) > ARGUMENT_THRESHOLD)

      return 1;

    if(RCChannel(CH_ROLL) < -ARGUMENT_THRESHOLD)

      return 5;

    return 9;

  }

}

/*

 * Abstract controls not used at the moment.

t_control rc_control = {

  RC_getPitch,

  RC_getRoll,

  RC_getYaw,

  RC_getThrottle,

  RC_getSignalQuality,

  RC_calibrate

};

*/