mirror of https://github.com/ArduPilot/ardupilot
99 lines
2.7 KiB
C++
99 lines
2.7 KiB
C++
/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
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#include <AP_Baro.h>
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#include "AP_Baro_HIL.h"
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#include <AP_HAL.h>
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extern const AP_HAL::HAL& hal;
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// Public Methods //////////////////////////////////////////////////////////////
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bool AP_Baro_HIL::init()
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{
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BMP085_State=1;
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return true;
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}
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// Read the sensor. This is a state machine
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// We read one time Temperature (state = 1) and then 4 times Pressure (states 2-5)
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uint8_t AP_Baro_HIL::read()
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{
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uint8_t result = 0;
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if (_count != 0) {
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result = 1;
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Press = ((float)_pressure_sum) / _count;
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Temp = ((float)_temperature_sum) / _count;
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_pressure_samples = _count;
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_count = 0;
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_pressure_sum = 0;
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_temperature_sum = 0;
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}
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return result;
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}
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// ==========================================================================
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// based on tables.cpp from http://www.pdas.com/atmosdownload.html
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/*
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Compute the temperature, density, and pressure in the standard atmosphere
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Correct to 20 km. Only approximate thereafter.
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*/
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static void SimpleAtmosphere(
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const float alt, // geometric altitude, km.
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float& sigma, // density/sea-level standard density
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float& delta, // pressure/sea-level standard pressure
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float& theta) // temperature/sea-level standard temperature
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{
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const float REARTH = 6369.0f; // radius of the Earth (km)
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const float GMR = 34.163195f; // gas constant
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float h=alt*REARTH/(alt+REARTH); // geometric to geopotential altitude
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if (h<11.0)
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{ // Troposphere
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theta=(288.15f-6.5f*h)/288.15f;
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delta=powf(theta, GMR/6.5f);
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}
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else
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{ // Stratosphere
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theta=216.65f/288.15f;
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delta=0.2233611f*expf(-GMR*(h-11.0f)/216.65f);
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}
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sigma=delta/theta;
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}
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void AP_Baro_HIL::setHIL(float altitude_msl)
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{
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float sigma, delta, theta;
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const float p0 = 101325;
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SimpleAtmosphere(altitude_msl*0.001, sigma, delta, theta);
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float p = p0 * delta;
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float T = 303.16 * theta - 273.16; // Assume 30 degrees at sea level - converted to degrees Kelvin
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_count++;
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_pressure_sum += p;
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_temperature_sum += T;
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if (_count == 128) {
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// we have summed 128 values. This only happens
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// when we stop reading the barometer for a long time
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// (more than 1.2 seconds)
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_count = 64;
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_pressure_sum /= 2;
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_temperature_sum /= 2;
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}
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healthy = true;
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_last_update = hal.scheduler->millis();
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}
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float AP_Baro_HIL::get_pressure() {
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return Press;
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}
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float AP_Baro_HIL::get_temperature() {
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return Temp;
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}
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