mirror of https://github.com/ArduPilot/ardupilot
86 lines
2.6 KiB
C++
86 lines
2.6 KiB
C++
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// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
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/*
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "AP_RangeFinder_LightWareI2C.h"
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#include <AP_HAL/AP_HAL.h>
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extern const AP_HAL::HAL& hal;
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/*
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The constructor also initialises the rangefinder. Note that this
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constructor is not called until detect() returns true, so we
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already know that we should setup the rangefinder
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*/
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AP_RangeFinder_LightWareI2C::AP_RangeFinder_LightWareI2C(RangeFinder &_ranger, uint8_t instance, RangeFinder::RangeFinder_State &_state) :
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AP_RangeFinder_Backend(_ranger, instance, _state)
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{
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}
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/*
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detect if a Lightware rangefinder is connected. We'll detect by
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trying to take a reading on I2C. If we get a result the sensor is
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there.
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*/
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bool AP_RangeFinder_LightWareI2C::detect(RangeFinder &_ranger, uint8_t instance)
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{
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uint8_t buff[2];
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if (_ranger._address[instance] == 0) {
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return false;
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}
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return hal.i2c->read(_ranger._address[instance], 2, &buff[0]) == 0;
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}
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// read - return last value measured by sensor
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bool AP_RangeFinder_LightWareI2C::get_reading(uint16_t &reading_cm)
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{
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uint8_t buff[2];
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// get pointer to i2c bus semaphore
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AP_HAL::Semaphore* i2c_sem = hal.i2c->get_semaphore();
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// exit immediately if we can't take the semaphore
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if (i2c_sem == NULL || !i2c_sem->take(1)) {
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return false;
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}
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// read the high and low byte distance registers
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if (hal.i2c->read(ranger._address[state.instance], 2, &buff[0]) != 0) {
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i2c_sem->give();
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return false;
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}
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// combine results into distance
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reading_cm = ((uint16_t)buff[0]) << 8 | buff[1];
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// return semaphore
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i2c_sem->give();
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return true;
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}
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/*
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update the state of the sensor
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*/
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void AP_RangeFinder_LightWareI2C::update(void)
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{
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if (get_reading(state.distance_cm)) {
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// update range_valid state based on distance measured
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update_status();
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} else {
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set_status(RangeFinder::RangeFinder_NoData);
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}
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}
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