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118 lines
3.6 KiB
118 lines
3.6 KiB
// -*- 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_PulsedLightLRF.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_PulsedLightLRF::AP_RangeFinder_PulsedLightLRF(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 PulsedLight 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_PulsedLightLRF::detect(RangeFinder &_ranger, uint8_t instance) |
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{ |
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if (!start_reading()) { |
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return false; |
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} |
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// give time for the sensor to process the request |
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hal.scheduler->delay(50); |
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uint16_t reading_cm; |
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return get_reading(reading_cm); |
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} |
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// start_reading() - ask sensor to make a range reading |
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bool AP_RangeFinder_PulsedLightLRF::start_reading() |
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{ |
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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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// send command to take reading |
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if (hal.i2c->writeRegister(AP_RANGEFINDER_PULSEDLIGHTLRF_ADDR, |
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AP_RANGEFINDER_PULSEDLIGHTLRF_MEASURE_REG, |
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AP_RANGEFINDER_PULSEDLIGHTLRF_MSRREG_ACQUIRE) != 0) { |
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i2c_sem->give(); |
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return false; |
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} |
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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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// read - return last value measured by sensor |
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bool AP_RangeFinder_PulsedLightLRF::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->readRegisters(AP_RANGEFINDER_PULSEDLIGHTLRF_ADDR, |
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AP_RANGEFINDER_PULSEDLIGHTLRF_DISTHIGH_REG, 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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// kick off another reading for next time |
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// To-Do: replace this with continuous mode |
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hal.scheduler->delay_microseconds(200); |
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start_reading(); |
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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_PulsedLightLRF::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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