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ardupilot/ArduPlane/px4_mixer.cpp

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// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
#include "Plane.h"
/*
handle creation of PX4 mixer file, for failover to direct RC control
on failure of FMU
This will create APM/MIXER.MIX on the microSD card. The user may
also create APM/CUSTOM.MIX, and if it exists that will be used
instead. That allows the user to setup more complex failsafe mixes
that include flaps, landing gear, ignition cut etc
*/
#if CONFIG_HAL_BOARD == HAL_BOARD_PX4
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <drivers/drv_pwm_output.h>
#include <systemlib/mixer/mixer.h>
#include <modules/px4iofirmware/protocol.h>
#define PX4_LIM_RC_MIN 900
#define PX4_LIM_RC_MAX 2100
/*
formatted print to a buffer with buffer advance. Returns true on
success, false on fail
*/
bool Plane::print_buffer(char *&buf, uint16_t &buf_size, const char *fmt, ...)
{
va_list arg_list;
va_start(arg_list, fmt);
int n = ::vsnprintf(buf, buf_size, fmt, arg_list);
va_end(arg_list);
if (n <= 0 || n >= buf_size) {
return false;
}
buf += n;
buf_size -= n;
return true;
}
/*
create a PX4 mixer buffer given the current fixed wing parameters
*/
bool Plane::create_mixer(char *buf, uint16_t buf_size, const char *filename)
{
char *buf0 = buf;
uint16_t buf_size0 = buf_size;
/*
this is the equivalent of channel_output_mixer()
*/
const int8_t mixmul[5][2] = { { 0, 0 }, { 1, 1 }, { 1, -1 }, { -1, 1 }, { -1, -1 }};
// these are the internal clipping limits. Use scale_max1 when
// clipping to user specified min/max is wanted. Use scale_max2
// when no clipping is wanted (simulated by setting a very large
// clipping value)
const float scale_max1 = 10000;
const float scale_max2 = 1000000;
// range for mixers
const uint16_t mix_max = scale_max1 * g.mixing_gain;
// scaling factors used by PX4IO between pwm and internal values,
// as configured in setup_failsafe_mixing() below
const float pwm_min = PX4_LIM_RC_MIN;
const float pwm_max = PX4_LIM_RC_MAX;
const float pwm_scale = 2*scale_max1/(pwm_max - pwm_min);
for (uint8_t i=0; i<8; i++) {
int32_t c1, c2, mix=0;
bool rev = false;
RC_Channel_aux::Aux_servo_function_t function = RC_Channel_aux::channel_function(i);
if (i == rcmap.pitch()-1 && g.vtail_output > MIXING_DISABLED && g.vtail_output <= MIXING_DNDN) {
// first channel of VTAIL mix
c1 = rcmap.yaw()-1;
c2 = i;
rev = false;
mix = -mix_max*mixmul[g.vtail_output][0];
} else if (i == rcmap.yaw()-1 && g.vtail_output > MIXING_DISABLED && g.vtail_output <= MIXING_DNDN) {
// second channel of VTAIL mix
c1 = rcmap.pitch()-1;
c2 = i;
rev = true;
mix = mix_max*mixmul[g.vtail_output][1];
} else if (i == rcmap.roll()-1 && g.elevon_output > MIXING_DISABLED &&
g.elevon_output <= MIXING_DNDN && g.vtail_output == 0) {
// first channel of ELEVON mix
c1 = i;
c2 = rcmap.pitch()-1;
rev = true;
mix = mix_max*mixmul[g.elevon_output][1];
} else if (i == rcmap.pitch()-1 && g.elevon_output > MIXING_DISABLED &&
g.elevon_output <= MIXING_DNDN && g.vtail_output == 0) {
// second channel of ELEVON mix
c1 = i;
c2 = rcmap.roll()-1;
rev = false;
mix = mix_max*mixmul[g.elevon_output][0];
} else if (function == RC_Channel_aux::k_aileron ||
function == RC_Channel_aux::k_flaperon1 ||
function == RC_Channel_aux::k_flaperon2) {
// a secondary aileron. We don't mix flap input in yet for flaperons
c1 = rcmap.roll()-1;
} else if (function == RC_Channel_aux::k_elevator) {
// a secondary elevator
c1 = rcmap.pitch()-1;
} else if (function == RC_Channel_aux::k_rudder ||
function == RC_Channel_aux::k_steering) {
// a secondary rudder or wheel
c1 = rcmap.yaw()-1;
} else if (g.flapin_channel > 0 &&
(function == RC_Channel_aux::k_flap ||
function == RC_Channel_aux::k_flap_auto)) {
// a flap output channel, and we have a manual flap input channel
c1 = g.flapin_channel-1;
} else if (i < 4 ||
function == RC_Channel_aux::k_elevator_with_input ||
function == RC_Channel_aux::k_aileron_with_input ||
function == RC_Channel_aux::k_manual) {
// a pass-thru channel
c1 = i;
} else {
// a empty output
if (!print_buffer(buf, buf_size, "Z:\n")) {
return false;
}
continue;
}
if (mix == 0) {
// pass thru channel, possibly with reversal. We also
// adjust the gain based on the range of input and output
// channels and adjust for trims
const RC_Channel *chan1 = RC_Channel::rc_channel(i);
const RC_Channel *chan2 = RC_Channel::rc_channel(c1);
int16_t chan1_trim = (i==rcmap.throttle()-1?1500:chan1->radio_trim);
int16_t chan2_trim = (c1==rcmap.throttle()-1?1500:chan2->radio_trim);
chan1_trim = constrain_int16(chan1_trim, PX4_LIM_RC_MIN+1, PX4_LIM_RC_MAX-1);
chan2_trim = constrain_int16(chan2_trim, PX4_LIM_RC_MIN+1, PX4_LIM_RC_MAX-1);
// if the input and output channels are the same then we
// apply clipping. This allows for direct pass-thru
int32_t limit = (c1==i?scale_max2:scale_max1);
int32_t in_scale_low;
if (chan2_trim <= chan2->radio_min) {
in_scale_low = scale_max1;
} else {
in_scale_low = scale_max1*(chan2_trim - pwm_min)/(float)(chan2_trim - chan2->radio_min);
}
int32_t in_scale_high;
if (chan2->radio_max <= chan2_trim) {
in_scale_high = scale_max1;
} else {
in_scale_high = scale_max1*(pwm_max - chan2_trim)/(float)(chan2->radio_max - chan2_trim);
}
if (chan1->get_reverse() != chan2->get_reverse()) {
in_scale_low = -in_scale_low;
in_scale_high = -in_scale_high;
}
if (!print_buffer(buf, buf_size, "M: 1\n") ||
!print_buffer(buf, buf_size, "O: %d %d %d %d %d\n",
(int)(pwm_scale*(chan1_trim - chan1->radio_min)),
(int)(pwm_scale*(chan1->radio_max - chan1_trim)),
(int)(pwm_scale*(chan1_trim - 1500)),
(int)-scale_max2, (int)scale_max2) ||
!print_buffer(buf, buf_size, "S: 0 %u %d %d %d %d %d\n", c1,
in_scale_low,
in_scale_high,
0,
-limit, limit)) {
return false;
}
} else {
const RC_Channel *chan1 = RC_Channel::rc_channel(c1);
const RC_Channel *chan2 = RC_Channel::rc_channel(c2);
int16_t chan1_trim = (c1==rcmap.throttle()-1?1500:chan1->radio_trim);
int16_t chan2_trim = (c2==rcmap.throttle()-1?1500:chan2->radio_trim);
chan1_trim = constrain_int16(chan1_trim, PX4_LIM_RC_MIN+1, PX4_LIM_RC_MAX-1);
chan2_trim = constrain_int16(chan2_trim, PX4_LIM_RC_MIN+1, PX4_LIM_RC_MAX-1);
// mix of two input channels to give an output channel. To
// make the mixer match the behaviour of APM we need to
// scale and offset the input channels to undo the affects
// of the PX4IO input processing
if (!print_buffer(buf, buf_size, "M: 2\n") ||
!print_buffer(buf, buf_size, "O: %d %d 0 %d %d\n", mix, mix, (int)-scale_max1, (int)scale_max1)) {
return false;
}
int32_t in_scale_low = pwm_scale*(chan1_trim - pwm_min);
int32_t in_scale_high = pwm_scale*(pwm_max - chan1_trim);
int32_t offset = pwm_scale*(chan1_trim - 1500);
if (!print_buffer(buf, buf_size, "S: 0 %u %d %d %d %d %d\n",
c1, in_scale_low, in_scale_high, offset,
(int)-scale_max2, (int)scale_max2)) {
return false;
}
in_scale_low = pwm_scale*(chan2_trim - pwm_min);
in_scale_high = pwm_scale*(pwm_max - chan2_trim);
offset = pwm_scale*(chan2_trim - 1500);
if (rev) {
if (!print_buffer(buf, buf_size, "S: 0 %u %d %d %d %d %d\n",
c2, in_scale_low, in_scale_high, offset,
(int)-scale_max2, (int)scale_max2)) {
return false;
}
} else {
if (!print_buffer(buf, buf_size, "S: 0 %u %d %d %d %d %d\n",
c2, -in_scale_low, -in_scale_high, -offset,
(int)-scale_max2, (int)scale_max2)) {
return false;
}
}
}
}
/*
if possible, also write to a file for debugging purposes
*/
int mix_fd = open(filename, O_WRONLY|O_CREAT|O_TRUNC, 0644);
if (mix_fd != -1) {
write(mix_fd, buf0, buf_size0 - buf_size);
close(mix_fd);
}
return true;
}
/*
setup mixer on PX4 so that if FMU dies the pilot gets manual control
*/
bool Plane::setup_failsafe_mixing(void)
{
const char *mixer_filename = "/fs/microsd/APM/MIXER.MIX";
bool ret = false;
char *buf = NULL;
const uint16_t buf_size = 2048;
buf = (char *)malloc(buf_size);
if (buf == NULL) {
return false;
}
if (!create_mixer(buf, buf_size, mixer_filename)) {
hal.console->printf("Unable to create mixer\n");
free(buf);
return false;
}
enum AP_HAL::Util::safety_state old_state = hal.util->safety_switch_state();
struct pwm_output_values pwm_values = {.values = {0}, .channel_count = 8};
int px4io_fd = open("/dev/px4io", 0);
if (px4io_fd == -1) {
// px4io isn't started, no point in setting up a mixer
free(buf);
return false;
}
if (old_state == AP_HAL::Util::SAFETY_ARMED) {
// make sure the throttle has a non-zero failsafe value before we
// disable safety. This prevents sending zero PWM during switch over
hal.rcout->set_safety_pwm(1UL<<(rcmap.throttle()-1), channel_throttle->radio_min);
}
// we need to force safety on to allow us to load a mixer. We call
// it twice as there have been reports that this call can fail
// with a small probability
hal.rcout->force_safety_on();
hal.rcout->force_safety_on();
/* reset any existing mixer in px4io. This shouldn't be needed,
* but is good practice */
if (ioctl(px4io_fd, MIXERIOCRESET, 0) != 0) {
hal.console->printf("Unable to reset mixer\n");
goto failed;
}
/* pass the buffer to the device */
if (ioctl(px4io_fd, MIXERIOCLOADBUF, (unsigned long)buf) != 0) {
hal.console->printf("Unable to send mixer to IO\n");
goto failed;
}
// setup RC config for each channel based on user specified
// mix/max/trim. We only do the first 8 channels due to
// a RC config limitation in px4io.c limiting to PX4IO_RC_MAPPED_CONTROL_CHANNELS
for (uint8_t i=0; i<8; i++) {
RC_Channel *ch = RC_Channel::rc_channel(i);
if (ch == NULL) {
continue;
}
struct pwm_output_rc_config config;
/*
we use a min/max of 900/2100 to allow for pass-thru of
larger values than the RC min/max range. This mimics the APM
behaviour of pass-thru in manual, which allows for dual-rate
transmitter setups in manual mode to go beyond the ranges
used in stabilised modes
*/
config.channel = i;
config.rc_min = 900;
config.rc_max = 2100;
if (rcmap.throttle()-1 == i) {
// throttle uses a trim of 1500, so we don't get division
// by small numbers near RC3_MIN
config.rc_trim = 1500;
} else {
config.rc_trim = constrain_int16(ch->radio_trim, config.rc_min+1, config.rc_max-1);
}
config.rc_dz = 0; // zero for the purposes of manual takeover
// we set reverse as false, as users of ArduPilot will have
// input reversed on transmitter, so from the point of view of
// the mixer the input is never reversed. The one exception is
// the 2nd channel, which is reversed inside the PX4IO code,
// so needs to be unreversed here to give sane behaviour.
if (i == 1) {
config.rc_reverse = true;
} else {
config.rc_reverse = false;
}
if (i+1 == g.override_channel.get()) {
/*
This is an OVERRIDE_CHAN channel. We want IO to trigger
override with a channel input of over 1750. The px4io
code is setup for triggering below 10% of full range. To
map this to values above 1750 we need to reverse the
direction and set the rc range for this channel to 1000
to 1833 (1833 = 1000 + 750/0.9)
*/
config.rc_assignment = PX4IO_P_RC_CONFIG_ASSIGNMENT_MODESWITCH;
config.rc_reverse = true;
config.rc_max = 1833;
config.rc_min = 1000;
config.rc_trim = 1500;
} else {
config.rc_assignment = i;
}
if (ioctl(px4io_fd, PWM_SERVO_SET_RC_CONFIG, (unsigned long)&config) != 0) {
hal.console->printf("SET_RC_CONFIG failed\n");
goto failed;
}
}
for (uint8_t i = 0; i < pwm_values.channel_count; i++) {
pwm_values.values[i] = 900;
}
if (ioctl(px4io_fd, PWM_SERVO_SET_MIN_PWM, (long unsigned int)&pwm_values) != 0) {
hal.console->printf("SET_MIN_PWM failed\n");
goto failed;
}
for (uint8_t i = 0; i < pwm_values.channel_count; i++) {
pwm_values.values[i] = 2100;
}
if (ioctl(px4io_fd, PWM_SERVO_SET_MAX_PWM, (long unsigned int)&pwm_values) != 0) {
hal.console->printf("SET_MAX_PWM failed\n");
goto failed;
}
if (ioctl(px4io_fd, PWM_SERVO_SET_OVERRIDE_OK, 0) != 0) {
hal.console->printf("SET_OVERRIDE_OK failed\n");
goto failed;
}
// setup for immediate manual control if FMU dies
if (ioctl(px4io_fd, PWM_SERVO_SET_OVERRIDE_IMMEDIATE, 1) != 0) {
hal.console->printf("SET_OVERRIDE_IMMEDIATE failed\n");
goto failed;
}
ret = true;
failed:
if (buf != NULL) {
free(buf);
}
if (px4io_fd != -1) {
close(px4io_fd);
}
// restore safety state if it was previously armed
if (old_state == AP_HAL::Util::SAFETY_ARMED) {
hal.rcout->force_safety_off();
hal.rcout->force_safety_off();
}
return ret;
}
#endif // CONFIG_HAL_BOARD
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