mirror of https://github.com/ArduPilot/ardupilot
257 lines
6.9 KiB
C++
257 lines
6.9 KiB
C++
/// -*- 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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/*
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BMP085 barometer driver. Based on original code by Jordi Munoz and
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Jose Julio
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Substantially modified by Andrew Tridgell
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*/
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#include <AP_HAL/AP_HAL.h>
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#include <AP_Common/AP_Common.h>
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#include "AP_Baro.h"
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extern const AP_HAL::HAL& hal;
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#define BMP085_ADDRESS 0x77 //(0xEE >> 1)
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#define BMP085_EOC 30 // End of conversion pin PC7 on APM1
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// the apm2 hardware needs to check the state of the
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// chip using a direct IO port
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// On APM2 prerelease hw, the data ready port is hooked up to PE7, which
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// is not available to the arduino digitalRead function.
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#if CONFIG_HAL_BOARD == HAL_BOARD_APM1
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#define BMP_DATA_READY() hal.gpio->read(BMP085_EOC)
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#else
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// No EOC connection from Baro
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// Use times instead.
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// Temp conversion time is 4.5ms
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// Pressure conversion time is 25.5ms (for OVERSAMPLING=3)
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#define BMP_DATA_READY() (BMP085_State == 0 ? hal.scheduler->millis() > (_last_temp_read_command_time + 5) : hal.scheduler->millis() > (_last_press_read_command_time + 26))
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#endif
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// oversampling 3 gives 26ms conversion time. We then average
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#define OVERSAMPLING 3
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/*
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constructor
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*/
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AP_Baro_BMP085::AP_Baro_BMP085(AP_Baro &baro) :
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AP_Baro_Backend(baro),
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_instance(0),
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_temp_sum(0),
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_press_sum(0),
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_count(0),
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BMP085_State(0),
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ac1(0), ac2(0), ac3(0), b1(0), b2(0), mb(0), mc(0), md(0),
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ac4(0), ac5(0), ac6(0),
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_retry_time(0)
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{
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uint8_t buff[22];
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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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// take i2c bus sempahore
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if (!i2c_sem->take(HAL_SEMAPHORE_BLOCK_FOREVER)) {
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hal.scheduler->panic(PSTR("BMP085: unable to get semaphore"));
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}
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// End Of Conversion (PC7) input
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hal.gpio->pinMode(BMP085_EOC, HAL_GPIO_INPUT);
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// We read the calibration data registers
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if (hal.i2c->readRegisters(BMP085_ADDRESS, 0xAA, 22, buff) != 0) {
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hal.scheduler->panic(PSTR("BMP085: bad calibration registers"));
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}
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ac1 = ((int16_t)buff[0] << 8) | buff[1];
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ac2 = ((int16_t)buff[2] << 8) | buff[3];
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ac3 = ((int16_t)buff[4] << 8) | buff[5];
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ac4 = ((int16_t)buff[6] << 8) | buff[7];
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ac5 = ((int16_t)buff[8] << 8) | buff[9];
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ac6 = ((int16_t)buff[10] << 8) | buff[11];
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b1 = ((int16_t)buff[12] << 8) | buff[13];
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b2 = ((int16_t)buff[14] << 8) | buff[15];
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mb = ((int16_t)buff[16] << 8) | buff[17];
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mc = ((int16_t)buff[18] << 8) | buff[19];
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md = ((int16_t)buff[20] << 8) | buff[21];
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_last_press_read_command_time = 0;
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_last_temp_read_command_time = 0;
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_instance = _frontend.register_sensor();
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//Send a command to read Temp
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Command_ReadTemp();
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BMP085_State = 0;
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i2c_sem->give();
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}
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// Read the sensor. This is a state machine
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// acumulate a new sensor reading
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void AP_Baro_BMP085::accumulate(void)
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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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if (!BMP_DATA_READY()) {
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return;
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}
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// take i2c bus sempahore
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if (!i2c_sem->take(1))
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return;
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if (BMP085_State == 0) {
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ReadTemp();
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} else {
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if (ReadPress()) {
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Calculate();
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}
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}
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BMP085_State++;
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if (BMP085_State == 5) {
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BMP085_State = 0;
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Command_ReadTemp();
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} else {
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Command_ReadPress();
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}
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i2c_sem->give();
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}
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/*
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transfer data to the frontend
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*/
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void AP_Baro_BMP085::update(void)
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{
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if (_count == 0 && BMP_DATA_READY()) {
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accumulate();
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}
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if (_count == 0) {
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return;
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}
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float temperature = 0.1f * _temp_sum / _count;
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float pressure = _press_sum / _count;
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_count = 0;
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_temp_sum = 0;
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_press_sum = 0;
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_copy_to_frontend(_instance, pressure, temperature);
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}
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// Send command to Read Pressure
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void AP_Baro_BMP085::Command_ReadPress()
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{
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// Mode 0x34+(OVERSAMPLING << 6) is osrs=3 when OVERSAMPLING=3 => 25.5ms conversion time
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hal.i2c->writeRegister(BMP085_ADDRESS, 0xF4,
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0x34+(OVERSAMPLING << 6));
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_last_press_read_command_time = hal.scheduler->millis();
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}
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// Read Raw Pressure values
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bool AP_Baro_BMP085::ReadPress()
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{
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uint8_t buf[3];
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if (hal.i2c->readRegisters(BMP085_ADDRESS, 0xF6, 3, buf) != 0) {
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_retry_time = hal.scheduler->millis() + 1000;
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hal.i2c->setHighSpeed(false);
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return false;
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}
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RawPress = (((uint32_t)buf[0] << 16)
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| ((uint32_t)buf[1] << 8)
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| ((uint32_t)buf[2])) >> (8 - OVERSAMPLING);
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return true;
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}
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// Send Command to Read Temperature
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void AP_Baro_BMP085::Command_ReadTemp()
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{
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hal.i2c->writeRegister(BMP085_ADDRESS, 0xF4, 0x2E);
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_last_temp_read_command_time = hal.scheduler->millis();
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}
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// Read Raw Temperature values
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void AP_Baro_BMP085::ReadTemp()
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{
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uint8_t buf[2];
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int32_t _temp_sensor;
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if (hal.i2c->readRegisters(BMP085_ADDRESS, 0xF6, 2, buf) != 0) {
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hal.i2c->setHighSpeed(false);
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return;
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}
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_temp_sensor = buf[0];
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_temp_sensor = (_temp_sensor << 8) | buf[1];
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RawTemp = _temp_sensor;
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}
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// Calculate Temperature and Pressure in real units.
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void AP_Baro_BMP085::Calculate()
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{
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int32_t x1, x2, x3, b3, b5, b6, p;
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uint32_t b4, b7;
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int32_t tmp;
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// See Datasheet page 13 for this formulas
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// Based also on Jee Labs BMP085 example code. Thanks for share.
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// Temperature calculations
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x1 = ((int32_t)RawTemp - ac6) * ac5 >> 15;
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x2 = ((int32_t) mc << 11) / (x1 + md);
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b5 = x1 + x2;
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_temp_sum += (b5 + 8) >> 4;
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// Pressure calculations
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b6 = b5 - 4000;
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x1 = (b2 * (b6 * b6 >> 12)) >> 11;
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x2 = ac2 * b6 >> 11;
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x3 = x1 + x2;
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//b3 = (((int32_t) ac1 * 4 + x3)<<OVERSAMPLING + 2) >> 2; // BAD
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//b3 = ((int32_t) ac1 * 4 + x3 + 2) >> 2; //OK for OVERSAMPLING=0
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tmp = ac1;
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tmp = (tmp*4 + x3)<<OVERSAMPLING;
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b3 = (tmp+2)/4;
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x1 = ac3 * b6 >> 13;
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x2 = (b1 * (b6 * b6 >> 12)) >> 16;
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x3 = ((x1 + x2) + 2) >> 2;
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b4 = (ac4 * (uint32_t) (x3 + 32768)) >> 15;
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b7 = ((uint32_t) RawPress - b3) * (50000 >> OVERSAMPLING);
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p = b7 < 0x80000000 ? (b7 * 2) / b4 : (b7 / b4) * 2;
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x1 = (p >> 8) * (p >> 8);
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x1 = (x1 * 3038) >> 16;
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x2 = (-7357 * p) >> 16;
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_press_sum += p + ((x1 + x2 + 3791) >> 4);
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_count++;
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if (_count == 254) {
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_temp_sum *= 0.5f;
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_press_sum *= 0.5f;
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_count /= 2;
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}
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}
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