rc.pde

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/***********************************************************
 * StoRC - Search to Rescue Craft
 * MEAM Senior Design 2011-2012
 * 
 * Authors:  Michael Posner (CIS, MEAM '12)
 * Timothy Hennelly (ESE '12)
 * Jacob Orloff (MEAM '12)
 * 
 * (some code from ArduPilot Mega project, found here:
 * http://code.google.com/p/ardupilot-mega/ )
 * 
 * Licensing:
 * 
 * This program is free software: you can redistribute it and/or modify 
 * it under the terms of the GNU General Public License as published by 
 * the Free Software Foundation, either version 3 of the License, or 
 * (at your option) any later version. 
 * 
 * This program is distributed in the hope that it will be useful, 
 * but WITHOUT ANY WARRANTY; without even the implied warranty of 
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
 * GNU General Public License for more details. 
 * 
 * You should have received a copy of the GNU General Public License 
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 * 
 ***********************************************************/

/**
 *  @file rc.pde
 *  @brief Commands for reading and updating RC values
 *  @author Michael Posner (CIS, MEAM '12)
 *  @author Timothy Hennelly (ESE '12)
 *  @author Jacob Orloff (MEAM '12)
 *  
 */


/**
 * Read RC values from the board (using the {@link APM_RC} library) and 
 * adjust them as necessary.
 * @see APM_RC
 */
void read_RC(void) {

  // If a new RC Input has been received, read RC Commands
  //if (APM_RC.GetState() == 1){

    rc_elevator = APM_RC.InputCh(ELEVATOR_CH);
    rc_rudder = APM_RC.InputCh(RUDDER_CH);
    rc_throttle = APM_RC.InputCh(THROTTLE_CH);

    rc_4 = APM_RC.InputCh(RC4_CH);
    rc_5 = APM_RC.InputCh(RC5_CH);
    rc_6 = APM_RC.InputCh(RC6_CH);
    rc_7 = APM_RC.InputCh(RC7_CH);
    rc_8 = APM_RC.InputCh(RC8_CH);

  //}

}


/**
 * Send RC commands to the board outputs (using the {@link APM_RC} library)
 * and make sure they are reasonable.
 * @see APM_RC
 */
void send_RC(void) {

  rc_elevator = constrain(rc_elevator,1000,2000);
  rc_throttle = constrain(rc_throttle,1000,2000);
  rc_rudder = constrain(rc_rudder,1000,2000);
  
  //Serial.print("sent ele: "); Serial.println(rc_elevator);
  APM_RC.OutputCh(ELEVATOR_CH,rc_elevator);
  APM_RC.OutputCh(RUDDER_CH,rc_rudder);
  APM_RC.OutputCh(THROTTLE_CH,rc_throttle);

}


/**
 * Check if the 4th RC channel is signaling a payload drop
 * @return true if ready to drop, false if not yet ready
 */
boolean check_drop(void){

  rc_4 = constrain(rc_4,1000,2000);

  if(rc_4 > 1700) {

    if(drop_timer == -1) { //intention to drop is news to us
      drop_timer = millis();
    }
    else if(millis() - drop_timer > 3000) { //yeah, you really wanna drop.  we get it
      drop_timer = -1;
      return true;
    }
    else { //not sure if you really wanna drop.... 
      return false;
    }

  }
  else if(rc_4 < 1700 && drop_timer != -1) {  //you dont really wanna drop
    drop_timer = -1;
  }
  else if(rc_4 < 1300) { //reset drop servo
    reset_drop();
  }
  
  return false;

}

/**
* Drop payload by sending output to the servo controlling the release.
*/
void drop_payload(void) {
  APM_RC.OutputCh(DROP_SERVO,800);
}

/**
* Reset the servo controlling the payload drop.
*/
void reset_drop(void) {
  APM_RC.OutputCh(DROP_SERVO,1500);
}


/**
 * Filter RC commands when they are read. This function limits the difference
 * between the current and previous reading to prevent wild readings from being
 * used.
 * @param rc the current RC value as read from the board
 * @param rc_old the previous RC value
 * @return the adjusted current RC value to be used
 */
int rc_filter(int rc, int rc_old) {

  int diff = rc - rc_old;  //difference between readings

  //if this is the first loop iteration, there is no old value so just return
  //  the current value
  if(rc_old == 0) {
    return rc;
  }

  //else limit things in some way

}