servos_ppm_hw.h

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/*
 * Copyright (C) 2008  Mark Griffin
 *
 * This file is part of paparazzi.
 *
 * paparazzi 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 2, or (at your option)
 * any later version.
 *
 * paparazzi 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 paparazzi; see the file COPYING.  If not, write to
 * the Free Software Foundation, 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 *
 */

#ifndef SERVOS_PPM_HW_H
#define SERVOS_PPM_HW_H

#include "std.h"
#include "LPC21xx.h"
#include "mcu_periph/sys_time.h"

#include BOARD_CONFIG

#define SERVOS_TICS_OF_USEC(s) cpu_ticks_of_usec(s)
#define ClipServo(x,a,b) Clip(x, a, b)

#define _PPM_NB_CHANNELS 8
extern uint16_t servos_values[_PPM_NB_CHANNELS];
#define ActuatorPpmSet(_i, _v) { servos_values[_i] = SERVOS_TICS_OF_USEC(_v); }

extern void actuators_ppm_init(void);
#define ActuatorsPpmCommit() {}
#define ActuatorsPpmInit() actuators_ppm_init()
extern uint8_t servos_PPM_idx;
extern uint32_t servos_delay;
extern uint8_t ppm_pulse; /* 1=start of pulse, 0=end of pulse */

/* define the ppm frame rate. 22msec is typical for JR/Graupner */
#define SERVO_REFRESH_TICS SERVOS_TICS_OF_USEC(22000)
/* define the ppm pulse width. 550usec is typical for JR/Graupner */
#define PPM_WIDTH SERVOS_TICS_OF_USEC(550)

#define ACTUATORS_IT TIR_MR1I
#define ServosPPMMat_ISR() {                                        \
    if (servos_PPM_idx == 0) {                                      \
      servos_delay = SERVO_REFRESH_TICS;                            \
    }                                                               \
    if (servos_PPM_idx < _PPM_NB_CHANNELS ) {                       \
      if (ppm_pulse) {                                              \
        T0MR1 += PPM_WIDTH;                                         \
        servos_delay -= PPM_WIDTH;                                  \
      } else {                                                      \
        T0MR1 += servos_values[servos_PPM_idx] - PPM_WIDTH;         \
        servos_delay -= servos_values[servos_PPM_idx] - PPM_WIDTH;  \
        servos_PPM_idx++;                                           \
      }                                                             \
    } else { /* servos_PPM_idx=_PPM_NB_CHANNELS */                  \
      if (ppm_pulse) {                                              \
        T0MR1 += PPM_WIDTH;                                         \
        servos_delay -= PPM_WIDTH;                                  \
      } else {                                                      \
        servos_PPM_idx = 0;                                         \
        T0MR1 += servos_delay - PPM_WIDTH;                          \
      }                                                             \
    }                                                               \
    if (!ppm_pulse) {                                               \
      /* lower clock pin */                                         \
      T0EMR &= ~TEMR_EM1;                                           \
    }                                                               \
    /* toggle ppm_pulse flag */                                     \
    ppm_pulse ^= 1;                                                 \
  }
#endif /* SERVOS_PPM_HW_H */