ardupilot/libraries/AP_RPM/RPM_PX4_PWM.cpp

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/*
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/>.
*/
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#include <AP_HAL/AP_HAL.h>
#if (CONFIG_HAL_BOARD == HAL_BOARD_PX4) || ((CONFIG_HAL_BOARD == HAL_BOARD_VRBRAIN) && (!defined(CONFIG_ARCH_BOARD_VRBRAIN_V51) && !defined(CONFIG_ARCH_BOARD_VRUBRAIN_V52)))
#include <AP_BoardConfig/AP_BoardConfig.h>
#include "RPM_PX4_PWM.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <drivers/drv_pwm_input.h>
#include <drivers/drv_hrt.h>
#include <drivers/drv_sensor.h>
#include <uORB/topics/pwm_input.h>
#include <stdio.h>
#include <errno.h>
#include <cmath>
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#define PWM_LOGGING 0
extern const AP_HAL::HAL& hal;
extern "C" {
int pwm_input_main(int, char **);
};
/*
open the sensor in constructor
*/
AP_RPM_PX4_PWM::AP_RPM_PX4_PWM(AP_RPM &_ap_rpm, uint8_t instance, AP_RPM::RPM_State &_state) :
AP_RPM_Backend(_ap_rpm, instance, _state)
{
#if HAL_PX4_HAVE_PWM_INPUT
if (AP_BoardConfig::px4_start_driver(pwm_input_main, "pwm_input", "start")) {
hal.console->printf("started pwm_input driver\n");
}
#endif
_fd = open(PWMIN0_DEVICE_PATH, O_RDONLY);
if (_fd == -1) {
hal.console->printf("Unable to open %s\n", PWMIN0_DEVICE_PATH);
return;
}
// keep a queue of 5 samples to reduce noise by averaging
if (ioctl(_fd, SENSORIOCSQUEUEDEPTH, 5) != 0) {
hal.console->printf("Failed to setup RPM queue\n");
close(_fd);
_fd = -1;
return;
}
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_resolution_usec = PWMIN_MINRPM_TO_RESOLUTION(((uint32_t)(ap_rpm._minimum[state.instance]+0.5f)));
ioctl(_fd, PWMINIOSRESOLUTION, _resolution_usec);
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#if PWM_LOGGING
_logfd = open("/fs/microsd/pwm.log", O_WRONLY|O_CREAT|O_TRUNC, 0644);
#endif
}
/*
close the file descriptor
*/
AP_RPM_PX4_PWM::~AP_RPM_PX4_PWM()
{
if (_fd != -1) {
close(_fd);
_fd = -1;
}
}
void AP_RPM_PX4_PWM::update(void)
{
if (_fd == -1) {
return;
}
uint32_t newres = PWMIN_MINRPM_TO_RESOLUTION(((uint32_t)(ap_rpm._minimum[state.instance]+0.5f)));
if (newres != _resolution_usec) {
ioctl(_fd, PWMINIOSRESOLUTION, newres);
_resolution_usec = newres;
}
struct pwm_input_s pwm;
uint16_t count = 0;
const float scaling = ap_rpm._scaling[state.instance];
float maximum = ap_rpm._maximum[state.instance];
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float minimum = ap_rpm._minimum[state.instance];
float quality = 0;
while (::read(_fd, &pwm, sizeof(pwm)) == sizeof(pwm)) {
// the px4 pwm_input driver reports the period in microseconds
if (pwm.period == 0) {
continue;
}
float rpm = scaling * (1.0e6f * 60) / pwm.period;
float filter_value = signal_quality_filter.get();
state.rate_rpm = signal_quality_filter.apply(rpm);
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if ((maximum <= 0 || rpm <= maximum) && (rpm >= minimum)) {
if (is_zero(filter_value)){
quality = 0;
} else {
quality = 1 - constrain_float((fabsf(rpm-filter_value))/filter_value, 0.0, 1.0);
quality = powf(quality, 2.0);
}
count++;
} else {
quality = 0;
}
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#if PWM_LOGGING
if (_logfd != -1) {
dprintf(_logfd, "%u %u %u\n",
(unsigned)pwm.timestamp/1000,
(unsigned)pwm.period,
(unsigned)pwm.pulse_width);
}
#endif
state.signal_quality = (0.1 * quality) + (0.9 * state.signal_quality); // simple LPF
}
if (count != 0) {
state.last_reading_ms = AP_HAL::millis();
}
// assume we get readings at at least 1Hz, otherwise reset quality to zero
if (AP_HAL::millis() - state.last_reading_ms > 1000) {
state.signal_quality = 0;
}
}
#endif // CONFIG_HAL_BOARD