ardupilot/libraries/AP_Airspeed/AP_Airspeed_DLVR.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_Airspeed_DLVR.h"
#include <AP_Math/AP_Math.h>
extern const AP_HAL::HAL &hal;
#define DLVR_I2C_ADDR 0x28
#ifdef DLVR_DEBUGGING
# define Debug(fmt, args ...) do {hal.console->printf("%s:%d: " fmt "\n", __FUNCTION__, __LINE__, ## args); hal.scheduler->delay(1); } while(0)
#else
# define Debug(fmt, args ...)
#endif
AP_Airspeed_DLVR::AP_Airspeed_DLVR(AP_Airspeed &_frontend, uint8_t _instance) :
AP_Airspeed_Backend(_frontend, _instance)
{}
// probe and initialise the sensor
bool AP_Airspeed_DLVR::init()
{
dev = hal.i2c_mgr->get_device(get_bus(), DLVR_I2C_ADDR);
if (!dev) {
return false;
}
dev->get_semaphore()->take_blocking();
dev->set_speed(AP_HAL::Device::SPEED_LOW);
dev->set_retries(2);
dev->get_semaphore()->give();
dev->register_periodic_callback(1000000UL/50U,
FUNCTOR_BIND_MEMBER(&AP_Airspeed_DLVR::timer, void));
return true;
}
#define STATUS_SHIFT 30
#define TEMPERATURE_SHIFT 5
#define TEMPERATURE_MASK ((1 << 11) - 1)
#define PRESSURE_SHIFT 16
#define PRESSURE_MASK ((1 << 14) - 1)
#define DLVR_FSS 5.0f // assumes 5 inch H2O sensor
#define DLVR_OFFSET 8192.0f
#define DLVR_SCALE 16384.0f
// 50Hz timer
void AP_Airspeed_DLVR::timer()
{
uint8_t raw_bytes[4];
if (!dev->read((uint8_t *)&raw_bytes, sizeof(raw_bytes))) {
return;
}
uint32_t data = (raw_bytes[0] << 24) |
(raw_bytes[1] << 16) |
(raw_bytes[2] << 8) |
raw_bytes[3];
if ((data >> STATUS_SHIFT)) {
// anything other then 00 in the status bits is an error
Debug("DLVR: Bad status read %d", data >> STATUS_SHIFT);
return;
}
uint32_t pres_raw = (data >> PRESSURE_SHIFT) & PRESSURE_MASK;
uint32_t temp_raw = (data >> TEMPERATURE_SHIFT) & TEMPERATURE_MASK;
float press_h2o = 1.25f * 2.0f * DLVR_FSS * ((pres_raw - DLVR_OFFSET) / DLVR_SCALE);
float temp = temp_raw * (200.0f / 2047.0f) - 50.0f;
sem->take_blocking();
pressure_sum += INCH_OF_H2O_TO_PASCAL * press_h2o;
temperature_sum += temp;
press_count++;
temp_count++;
last_sample_time_ms = AP_HAL::millis();
sem->give();
}
// return the current differential_pressure in Pascal
bool AP_Airspeed_DLVR::get_differential_pressure(float &_pressure)
{
if ((AP_HAL::millis() - last_sample_time_ms) > 100) {
return false;
}
if (sem->take(HAL_SEMAPHORE_BLOCK_FOREVER)) {
if (press_count > 0) {
pressure = pressure_sum / press_count;
press_count = 0;
pressure_sum = 0;
}
sem->give();
}
_pressure = pressure;
return true;
}
// return the current temperature in degrees C, if available
bool AP_Airspeed_DLVR::get_temperature(float &_temperature)
{
if ((AP_HAL::millis() - last_sample_time_ms) > 100) {
return false;
}
if (sem->take(HAL_SEMAPHORE_BLOCK_FOREVER)) {
if (temp_count > 0) {
temperature = temperature_sum / temp_count;
temp_count = 0;
temperature_sum = 0;
}
sem->give();
}
_temperature = temperature;
return true;
}