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/****************************************************************************
*
* Copyright (C) 2012 PX4 Development Team. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name PX4 nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/**
* @file mixer.c
*
* Control channel input/output mixer and failsafe.
*/
#include <nuttx/config.h>
#include <nuttx/arch.h>
#include <sys/types.h>
#include <stdbool.h>
#include <string.h>
#include <assert.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <drivers/drv_pwm_output.h>
#include <systemlib/ppm_decode.h>
#include "px4io.h"
/*
* Count of periodic calls in which we have no FMU input.
*/
static unsigned fmu_input_drops;
#define FMU_INPUT_DROP_LIMIT 20
/*
* Collect RC input data from the controller source(s).
*/
static void mixer_get_rc_input(void);
/*
* Update a mixer based on the current control signals.
*/
static void mixer_update(int mixer, uint16_t *inputs, int input_count);
/* current servo arm/disarm state */
bool mixer_servos_armed = false;
/*
* Each mixer consumes a set of inputs and produces a single output.
*/
struct mixer {
uint16_t current_value;
/* XXX more config here */
} mixers[IO_SERVO_COUNT];
void
mixer_tick(void)
{
uint16_t *control_values;
int control_count;
int i;
bool should_arm;
/*
* Start by looking for R/C control inputs.
* This updates system_state with any control inputs received.
*/
mixer_get_rc_input();
/*
* Decide which set of inputs we're using.
*/
if (system_state.mixer_use_fmu) {
/* we have recent control data from the FMU */
control_count = PX4IO_OUTPUT_CHANNELS;
control_values = &system_state.fmu_channel_data[0];
/* check that we are receiving fresh data from the FMU */
if (!system_state.fmu_data_received) {
fmu_input_drops++;
/* too many frames without FMU input, time to go to failsafe */
if (fmu_input_drops >= FMU_INPUT_DROP_LIMIT) {
system_state.mixer_use_fmu = false;
}
} else {
fmu_input_drops = 0;
system_state.fmu_data_received = false;
}
} else if (system_state.rc_channels > 0) {
/* we have control data from an R/C input */
control_count = system_state.rc_channels;
control_values = &system_state.rc_channel_data[0];
} else {
/* we have no control input */
control_count = 0;
}
/*
* Tickle each mixer, if we have control data.
*/
if (control_count > 0) {
for (i = 0; i < IO_SERVO_COUNT; i++) {
mixer_update(i, control_values, control_count);
/*
* If we are armed, update the servo output.
*/
if (system_state.armed && system_state.arm_ok)
up_pwm_servo_set(i, mixers[i].current_value);
}
}
/*
* Decide whether the servos should be armed right now.
*/
should_arm = system_state.armed && system_state.arm_ok && (control_count > 0) && system_state.mixer_use_fmu;
if (should_arm && !mixer_servos_armed) {
/* need to arm, but not armed */
up_pwm_servo_arm(true);
mixer_servos_armed = true;
} else if (!should_arm && mixer_servos_armed) {
/* armed but need to disarm */
up_pwm_servo_arm(false);
mixer_servos_armed = false;
}
}
static void
mixer_update(int mixer, uint16_t *inputs, int input_count)
{
/* simple passthrough for now */
if (mixer < input_count) {
mixers[mixer].current_value = inputs[mixer];
} else {
mixers[mixer].current_value = 0;
}
}
static void
mixer_get_rc_input(void)
{
/* if we haven't seen any new data in 200ms, assume we have lost input and tell FMU */
if ((hrt_absolute_time() - ppm_last_valid_decode) > 200000) {
/* input was ok and timed out, mark as update */
if (system_state.ppm_input_ok) {
system_state.ppm_input_ok = false;
system_state.fmu_report_due = true;
}
return;
}
/* mark PPM as valid */
system_state.ppm_input_ok = true;
/* check if no DSM and S.BUS data is available */
if (!system_state.sbus_input_ok && !system_state.dsm_input_ok) {
/* otherwise, copy channel data */
system_state.rc_channels = ppm_decoded_channels;
for (unsigned i = 0; i < ppm_decoded_channels; i++)
system_state.rc_channel_data[i] = ppm_buffer[i];
system_state.fmu_report_due = true;
}
}
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