ardupilot/libraries/AP_RangeFinder/AP_RangeFinder_MaxsonarI2CX...

126 lines
3.6 KiB
C++

// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
/*
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/>.
*/
/*
* AP_RangeFinder_MaxsonarI2CXL.cpp - Arduino Library for MaxBotix I2C XL sonar
* Code by Randy Mackay. DIYDrones.com
*
* datasheet: http://www.maxbotix.com/documents/I2CXL-MaxSonar-EZ_Datasheet.pdf
*
* Sensor should be connected to the I2C port
*/
#include "AP_RangeFinder_MaxsonarI2CXL.h"
#include <AP_HAL/AP_HAL.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_MaxsonarI2CXL::AP_RangeFinder_MaxsonarI2CXL(RangeFinder &_ranger, uint8_t instance, RangeFinder::RangeFinder_State &_state) :
AP_RangeFinder_Backend(_ranger, instance, _state)
{
}
/*
detect if a Maxbotix rangefinder is connected. We'll detect by
trying to take a reading on I2C. If we get a result the sensor is
there.
*/
bool AP_RangeFinder_MaxsonarI2CXL::detect(RangeFinder &_ranger, uint8_t instance)
{
if (!start_reading()) {
return false;
}
// give time for the sensor to process the request
hal.scheduler->delay(50);
uint16_t reading_cm;
return get_reading(reading_cm);
}
// start_reading() - ask sensor to make a range reading
bool AP_RangeFinder_MaxsonarI2CXL::start_reading()
{
// get pointer to i2c bus semaphore
AP_HAL::Semaphore* i2c_sem = hal.i2c->get_semaphore();
// exit immediately if we can't take the semaphore
if (i2c_sem == NULL || !i2c_sem->take(1)) {
return false;
}
uint8_t tosend[1] =
{ AP_RANGE_FINDER_MAXSONARI2CXL_COMMAND_TAKE_RANGE_READING };
// send command to take reading
if (hal.i2c->write(AP_RANGE_FINDER_MAXSONARI2CXL_DEFAULT_ADDR,
1, tosend) != 0) {
i2c_sem->give();
return false;
}
// return semaphore
i2c_sem->give();
return true;
}
// read - return last value measured by sensor
bool AP_RangeFinder_MaxsonarI2CXL::get_reading(uint16_t &reading_cm)
{
uint8_t buff[2];
// get pointer to i2c bus semaphore
AP_HAL::Semaphore* i2c_sem = hal.i2c->get_semaphore();
// exit immediately if we can't take the semaphore
if (i2c_sem == NULL || !i2c_sem->take(1)) {
return false;
}
// take range reading and read back results
if (hal.i2c->read(AP_RANGE_FINDER_MAXSONARI2CXL_DEFAULT_ADDR, 2, buff) != 0) {
i2c_sem->give();
return false;
}
i2c_sem->give();
// combine results into distance
reading_cm = ((uint16_t)buff[0]) << 8 | buff[1];
// trigger a new reading
start_reading();
return true;
}
/*
update the state of the sensor
*/
void AP_RangeFinder_MaxsonarI2CXL::update(void)
{
if (get_reading(state.distance_cm)) {
// update range_valid state based on distance measured
update_status();
} else {
set_status(RangeFinder::RangeFinder_NoData);
}
}