ardupilot/libraries/AP_RangeFinder/AP_RangeFinder_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/>.
*/
#include "AP_RangeFinder_PWM.h"
#include <AP_HAL/AP_HAL.h>
#include <GCS_MAVLink/GCS.h>
extern const AP_HAL::HAL& hal;
/*
The constructor also initialises the rangefinder.
*/
AP_RangeFinder_PWM::AP_RangeFinder_PWM(RangeFinder::RangeFinder_State &_state,
AP_RangeFinder_Params &_params,
float &_estimated_terrain_height) :
AP_RangeFinder_Backend(_state, _params),
estimated_terrain_height(_estimated_terrain_height)
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{
}
/*
There's no sensible way of detecting a PWM rangefinder as the pins are configurable
*/
bool AP_RangeFinder_PWM::detect()
{
return true;
}
// interrupt handler for reading pwm value
void AP_RangeFinder_PWM::irq_handler(uint8_t pin, bool pin_high, uint32_t timestamp_us)
{
if (pin_high) {
irq_pulse_start_us = timestamp_us;
} else {
if (irq_pulse_start_us != 0) {
irq_value_us += timestamp_us - irq_pulse_start_us;
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irq_pulse_start_us = 0;
irq_sample_count++;
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}
}
}
// read - return last value measured by sensor
bool AP_RangeFinder_PWM::get_reading(uint16_t &reading_cm)
{
// disable interrupts and grab state
void *irqstate = hal.scheduler->disable_interrupts_save();
const uint32_t value_us = irq_value_us;
const uint16_t sample_count = irq_sample_count;
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irq_value_us = 0;
irq_sample_count = 0;
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hal.scheduler->restore_interrupts(irqstate);
if (value_us == 0 || sample_count == 0) {
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return false;
}
reading_cm = value_us/(sample_count * 10); // correct for LidarLite. Parameter needed? Converts from decimetres -> cm here
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return true;
}
void AP_RangeFinder_PWM::check_pin()
{
if (params.pin == last_pin) {
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return;
}
// detach last one
if (last_pin > 0) {
if (!hal.gpio->detach_interrupt(last_pin)) {
gcs().send_text(MAV_SEVERITY_WARNING,
"RangeFinder_PWM: Failed to detach from pin %u",
last_pin);
// ignore this failure or the user may be stuck
}
}
// set last pin to params.pin so we don't continually try to attach
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// to it if the attach is failing
last_pin = params.pin;
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if (params.pin <= 0) {
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// don't need to install handler
return;
}
// install interrupt handler on rising and falling edge
hal.gpio->pinMode(params.pin, HAL_GPIO_INPUT);
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if (!hal.gpio->attach_interrupt(
params.pin,
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FUNCTOR_BIND_MEMBER(&AP_RangeFinder_PWM::irq_handler,
void,
uint8_t,
bool,
uint32_t),
AP_HAL::GPIO::INTERRUPT_BOTH)) {
// failed to attach interrupt
gcs().send_text(MAV_SEVERITY_WARNING,
"RangeFinder_PWM: Failed to attach to pin %u",
(unsigned int)params.pin);
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return;
}
}
void AP_RangeFinder_PWM::check_stop_pin()
{
if (params.stop_pin == last_stop_pin) {
return;
}
hal.gpio->pinMode(params.stop_pin, HAL_GPIO_OUTPUT);
last_stop_pin = params.stop_pin;
}
void AP_RangeFinder_PWM::check_pins()
{
check_pin();
check_stop_pin();
}
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/*
update the state of the sensor
*/
void AP_RangeFinder_PWM::update(void)
{
// check if pin has changed and configure interrupt handlers if required:
check_pins();
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if (last_pin <= 0) {
// disabled (by configuration)
return;
}
if (params.stop_pin != -1) {
const bool oor = out_of_range();
if (oor) {
if (!was_out_of_range) {
// we are above the power saving range. Disable the sensor
hal.gpio->write(params.stop_pin, false);
set_status(RangeFinder::Status::NoData);
state.distance_cm = 0;
state.voltage_mv = 0;
was_out_of_range = oor;
}
return;
}
// re-enable the sensor:
if (!oor && was_out_of_range) {
hal.gpio->write(params.stop_pin, true);
was_out_of_range = oor;
}
}
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if (!get_reading(state.distance_cm)) {
// failure; consider changing our state
if (AP_HAL::millis() - state.last_reading_ms > 200) {
set_status(RangeFinder::Status::NoData);
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}
return;
}
// update range_valid state based on distance measured
state.last_reading_ms = AP_HAL::millis();
update_status();
}
// return true if we are beyond the power saving range
bool AP_RangeFinder_PWM::out_of_range(void) const {
return params.powersave_range > 0 && estimated_terrain_height > params.powersave_range;
}