ardupilot/libraries/AP_RangeFinder/AP_RangeFinder_TeraRangerI2...

168 lines
4.2 KiB
C++

/*
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/>.
*/
/*
driver for TeraRanger I2C rangefinders
*/
#include "AP_RangeFinder_TeraRangerI2C.h"
#include <utility>
#include <AP_HAL/AP_HAL.h>
#include <AP_Math/crc.h>
extern const AP_HAL::HAL& hal;
// registers
#define TR_MEASURE 0x00
#define TR_WHOAMI 0x01
#define TR_WHOAMI_VALUE 0xA1
/*
The constructor also initializes 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_TeraRangerI2C::AP_RangeFinder_TeraRangerI2C(RangeFinder::RangeFinder_State &_state,
AP_HAL::OwnPtr<AP_HAL::I2CDevice> i2c_dev)
: AP_RangeFinder_Backend(_state)
, dev(std::move(i2c_dev))
{
}
/*
detect if a TeraRanger rangefinder is connected. We'll detect by
trying to take a reading on I2C. If we get a result the sensor is
there.
*/
AP_RangeFinder_Backend *AP_RangeFinder_TeraRangerI2C::detect(RangeFinder::RangeFinder_State &_state,
AP_HAL::OwnPtr<AP_HAL::I2CDevice> i2c_dev)
{
AP_RangeFinder_TeraRangerI2C *sensor = new AP_RangeFinder_TeraRangerI2C(_state, std::move(i2c_dev));
if (!sensor) {
return nullptr;
}
if (!sensor->init()) {
delete sensor;
return nullptr;
}
return sensor;
}
/*
initialise sensor
*/
bool AP_RangeFinder_TeraRangerI2C::init(void)
{
if (!dev->get_semaphore()->take(HAL_SEMAPHORE_BLOCK_FOREVER)) {
return false;
}
dev->set_retries(10);
// check WHOAMI
uint8_t whoami;
if (!dev->read_registers(TR_WHOAMI, &whoami, 1) ||
whoami != TR_WHOAMI_VALUE) {
return false;
}
if (!measure()) {
dev->get_semaphore()->give();
return false;
}
// give time for the sensor to process the request
hal.scheduler->delay(70);
uint16_t _distance_cm;
if (!collect(_distance_cm)) {
dev->get_semaphore()->give();
return false;
}
dev->get_semaphore()->give();
dev->set_retries(1);
dev->register_periodic_callback(50000,
FUNCTOR_BIND_MEMBER(&AP_RangeFinder_TeraRangerI2C::timer, void));
return true;
}
// measure() - ask sensor to make a range reading
bool AP_RangeFinder_TeraRangerI2C::measure()
{
uint8_t cmd = TR_MEASURE;
return dev->transfer(&cmd, 1, nullptr, 0);
}
// collect - return last value measured by sensor
bool AP_RangeFinder_TeraRangerI2C::collect(uint16_t &_distance_cm)
{
uint8_t d[3];
// take range reading and read back results
if (!dev->transfer(nullptr, 0, d, sizeof(d))) {
return false;
}
if (d[2] != crc_crc8(d, 2)) {
// bad CRC
return false;
}
_distance_cm = ((uint16_t(d[0]) << 8) | d[1]) / 10;
return true;
}
/*
timer called at 20Hz
*/
void AP_RangeFinder_TeraRangerI2C::timer(void)
{
// take a reading
uint16_t _distance_cm;
if (collect(_distance_cm) && _sem->take(HAL_SEMAPHORE_BLOCK_FOREVER)) {
accum.sum += _distance_cm;
accum.count++;
_sem->give();
}
// and immediately ask for a new reading
measure();
}
/*
update the state of the sensor
*/
void AP_RangeFinder_TeraRangerI2C::update(void)
{
if (_sem->take(HAL_SEMAPHORE_BLOCK_FOREVER)) {
if (accum.count > 0) {
state.distance_cm = accum.sum / accum.count;
accum.sum = 0;
accum.count = 0;
update_status();
} else {
set_status(RangeFinder::RangeFinder_NoData);
}
_sem->give();
}
}