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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.cpp
*
* 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/mixer/mixer.h>
extern "C" {
#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
/* current servo arm/disarm state */
bool mixer_servos_armed = false;
/* selected control values and count for mixing */
static uint16_t *control_values;
static int control_count;
static int mixer_callback(uintptr_t handle,
uint8_t control_group,
uint8_t control_index,
float &control);
static MixerGroup mixer_group(mixer_callback, 0);
void
mixer_tick(void)
{
bool should_arm;
/*
* 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 */
/* XXX builtin failsafe would activate here */
control_count = 0;
}
/*
* Run the mixers if we have any control data at all.
*/
if (control_count > 0) {
float outputs[IO_SERVO_COUNT];
unsigned mixed;
/* mix */
mixed = mixer_group.mix(&outputs[0], IO_SERVO_COUNT);
/* scale to PWM and update the servo outputs as required */
for (unsigned i = 0; i < IO_SERVO_COUNT; i++) {
if (i < mixed) {
/* scale to servo output */
system_state.servos[i] = (outputs[i] * 1000.0f) + 1000;
} else {
/* set to zero to inhibit PWM pulse output */
system_state.servos[i] = 0;
}
/*
* If we are armed, update the servo output.
*/
if (system_state.armed && system_state.arm_ok)
up_pwm_servo_set(i, system_state.servos[i]);
}
}
/*
* Decide whether the servos should be armed right now.
*/
should_arm = system_state.armed && system_state.arm_ok && (control_count > 0);
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 int
mixer_callback(uintptr_t handle,
uint8_t control_group,
uint8_t control_index,
float &control)
{
/* if the control index refers to an input that's not valid, we can't return it */
if (control_index >= control_count)
return -1;
/* scale from current PWM units (1000-2000) to mixer input values */
/* XXX this presents some ugly problems w.r.t failsafe and R/C input scaling that have to be addressed */
control = ((float)control_values[control_index] - 1000.0f) / 1000.0f;
return 0;
}
void
mixer_handle_text(const void *buffer, size_t length)
{
static char mixer_text[256];
static unsigned mixer_text_length = 0;
px4io_mixdata *msg = (px4io_mixdata *)buffer;
if (length < sizeof(px4io_mixdata))
return;
unsigned text_length = length - sizeof(px4io_mixdata);
switch (msg->action) {
case F2I_MIXER_ACTION_RESET:
mixer_group.reset();
mixer_text_length = 0;
/* FALLTHROUGH */
case F2I_MIXER_ACTION_APPEND:
/* check for overflow - this is really fatal */
if ((mixer_text_length + text_length + 1) > sizeof(mixer_text))
return;
/* append mixer text and nul-terminate */
memcpy(&mixer_text[mixer_text_length], msg->text, text_length);
mixer_text_length += text_length;
mixer_text[mixer_text_length] = '\0';
/* process the text buffer, adding new mixers as their descriptions can be parsed */
char *end = &mixer_text[mixer_text_length];
mixer_group.load_from_buf(&mixer_text[0], mixer_text_length);
/* copy any leftover text to the base of the buffer for re-use */
if (mixer_text_length > 0)
memcpy(&mixer_text[0], end - mixer_text_length, mixer_text_length);
break;
}
}
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