ardupilot/libraries/AP_RangeFinder/AP_RangeFinder_uLanding.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_HAL/AP_HAL.h>
#include "AP_RangeFinder_uLanding.h"
#include <AP_SerialManager/AP_SerialManager.h>
#include <ctype.h>
extern const AP_HAL::HAL& hal;
/*
The constructor also initialises the rangefinder. Note that this
constructor is not called until detect() returns true, so we
already know that we should setup the rangefinder
*/
AP_RangeFinder_uLanding::AP_RangeFinder_uLanding(RangeFinder &_ranger, uint8_t instance,
RangeFinder::RangeFinder_State &_state,
AP_SerialManager &serial_manager) :
AP_RangeFinder_Backend(_ranger, instance, _state)
{
uart = serial_manager.find_serial(AP_SerialManager::SerialProtocol_Aerotenna_uLanding, 0);
if (uart != nullptr) {
uart->begin(serial_manager.find_baudrate(AP_SerialManager::SerialProtocol_Aerotenna_uLanding, 0));
}
}
/*
detect if a uLanding rangefinder is connected. We'll detect by
trying to take a reading on Serial. If we get a result the sensor is
there.
*/
bool AP_RangeFinder_uLanding::detect(RangeFinder &_ranger, uint8_t instance, AP_SerialManager &serial_manager)
{
return serial_manager.find_serial(AP_SerialManager::SerialProtocol_Aerotenna_uLanding, 0) != nullptr;
}
// read - return last value measured by sensor
bool AP_RangeFinder_uLanding::get_reading(uint16_t &reading_cm)
{
if (uart == nullptr) {
return false;
}
// read any available lines from the uLanding
float sum = 0;
uint16_t count = 0;
uint8_t index = 0;
int16_t nbytes = uart->available();
while (nbytes-- > 0) {
uint8_t c = uart->read();
// ok, we have located start byte
if (c == 72 && index == 0) {
linebuf_len = 0;
index = 1;
}
// now it is ready to decode index information
if (index == 1) {
linebuf[linebuf_len] = c;
linebuf_len ++;
if (linebuf_len == 3) {
index = 0;
sum += (linebuf[2]&0x7F) *128 + (linebuf[1]&0x7F);
linebuf_len = 0;
count ++;
}
}
}
if (count == 0) {
return false;
}
reading_cm = 2.5f * sum / count;
return true;
}
/*
update the state of the sensor
*/
void AP_RangeFinder_uLanding::update(void)
{
if (get_reading(state.distance_cm)) {
// update range_valid state based on distance measured
last_reading_ms = AP_HAL::millis();
update_status();
} else if (AP_HAL::millis() - last_reading_ms > 200) {
set_status(RangeFinder::RangeFinder_NoData);
}
}