mirror of https://github.com/ArduPilot/ardupilot
293 lines
8.6 KiB
C++
293 lines
8.6 KiB
C++
/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
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/*
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* APM_MS5611.cpp - Arduino Library for MS5611-01BA01 absolute pressure sensor
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* Code by Jose Julio, Pat Hickey and Jordi Muñoz. DIYDrones.com
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* Sensor is conected to standard SPI port
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* Chip Select pin: Analog2 (provisional until Jordi defines the pin)!!
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*
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* Variables:
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* Temp : Calculated temperature (in Celsius degrees * 100)
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* Press : Calculated pressure (in mbar units * 100)
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*
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*
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* Methods:
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* init() : Initialization and sensor reset
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* read() : Read sensor data and _calculate Temperature, Pressure
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* This function is optimized so the main host don´t need to wait
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* You can call this function in your main loop
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* Maximum data output frequency 100Hz - this allows maximum oversampling in the chip ADC
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* It returns a 1 if there are new data.
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* get_pressure() : return pressure in mbar*100 units
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* get_temperature() : return temperature in celsius degrees*100 units
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*
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* Internal functions:
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* _calculate() : Calculate Temperature and Pressure (temperature compensated) in real units
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*
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*
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*/
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#include <FastSerial.h>
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#include <SPI.h>
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#include "AP_Baro_MS5611.h"
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/* on APM v.24 MS5661_CS is PG1 (Arduino pin 40) */
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#define MS5611_CS 40
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#define CMD_MS5611_RESET 0x1E
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#define CMD_MS5611_PROM_Setup 0xA0
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#define CMD_MS5611_PROM_C1 0xA2
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#define CMD_MS5611_PROM_C2 0xA4
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#define CMD_MS5611_PROM_C3 0xA6
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#define CMD_MS5611_PROM_C4 0xA8
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#define CMD_MS5611_PROM_C5 0xAA
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#define CMD_MS5611_PROM_C6 0xAC
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#define CMD_MS5611_PROM_CRC 0xAE
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#define CMD_CONVERT_D1_OSR4096 0x48 // Maximum resolution (oversampling)
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#define CMD_CONVERT_D2_OSR4096 0x58 // Maximum resolution (oversampling)
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uint32_t volatile AP_Baro_MS5611::_s_D1;
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uint32_t volatile AP_Baro_MS5611::_s_D2;
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uint8_t volatile AP_Baro_MS5611::_d1_count;
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uint8_t volatile AP_Baro_MS5611::_d2_count;
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uint8_t AP_Baro_MS5611::_state;
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uint32_t AP_Baro_MS5611::_timer;
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bool volatile AP_Baro_MS5611::_updated;
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uint8_t AP_Baro_MS5611::_spi_read(uint8_t reg)
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{
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uint8_t return_value;
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uint8_t addr = reg; // | 0x80; // Set most significant bit
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digitalWrite(MS5611_CS, LOW);
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SPI.transfer(addr); // discarded
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return_value = SPI.transfer(0);
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digitalWrite(MS5611_CS, HIGH);
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return return_value;
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}
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uint16_t AP_Baro_MS5611::_spi_read_16bits(uint8_t reg)
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{
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uint8_t byteH, byteL;
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uint16_t return_value;
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uint8_t addr = reg; // | 0x80; // Set most significant bit
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digitalWrite(MS5611_CS, LOW);
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SPI.transfer(addr); // discarded
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byteH = SPI.transfer(0);
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byteL = SPI.transfer(0);
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digitalWrite(MS5611_CS, HIGH);
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return_value = ((uint16_t)byteH<<8) | (byteL);
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return return_value;
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}
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uint32_t AP_Baro_MS5611::_spi_read_adc()
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{
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uint8_t byteH,byteM,byteL;
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uint32_t return_value;
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uint8_t addr = 0x00;
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digitalWrite(MS5611_CS, LOW);
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SPI.transfer(addr); // discarded
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byteH = SPI.transfer(0);
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byteM = SPI.transfer(0);
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byteL = SPI.transfer(0);
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digitalWrite(MS5611_CS, HIGH);
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return_value = (((uint32_t)byteH)<<16) | (((uint32_t)byteM)<<8) | (byteL);
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return return_value;
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}
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void AP_Baro_MS5611::_spi_write(uint8_t reg)
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{
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digitalWrite(MS5611_CS, LOW);
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SPI.transfer(reg); // discarded
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digitalWrite(MS5611_CS, HIGH);
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}
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// Public Methods //////////////////////////////////////////////////////////////
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// SPI should be initialized externally
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bool AP_Baro_MS5611::init( AP_PeriodicProcess *scheduler )
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{
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scheduler->suspend_timer();
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pinMode(MS5611_CS, OUTPUT); // Chip select Pin
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digitalWrite(MS5611_CS, HIGH);
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delay(1);
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_spi_write(CMD_MS5611_RESET);
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delay(4);
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// We read the factory calibration
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// The on-chip CRC is not used
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C1 = _spi_read_16bits(CMD_MS5611_PROM_C1);
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C2 = _spi_read_16bits(CMD_MS5611_PROM_C2);
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C3 = _spi_read_16bits(CMD_MS5611_PROM_C3);
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C4 = _spi_read_16bits(CMD_MS5611_PROM_C4);
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C5 = _spi_read_16bits(CMD_MS5611_PROM_C5);
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C6 = _spi_read_16bits(CMD_MS5611_PROM_C6);
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//Send a command to read Temp first
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_spi_write(CMD_CONVERT_D2_OSR4096);
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_timer = micros();
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_state = 0;
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Temp=0;
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Press=0;
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_s_D1 = 0;
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_s_D2 = 0;
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_d1_count = 0;
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_d2_count = 0;
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scheduler->resume_timer();
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scheduler->register_process( AP_Baro_MS5611::_update );
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// wait for at least one value to be read
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while (!_updated) ;
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healthy = true;
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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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// temperature does not change so quickly...
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void AP_Baro_MS5611::_update(uint32_t tnow)
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{
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// Throttle read rate to 100hz maximum.
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// note we use 9500us here not 10000us
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// the read rate will end up at exactly 100hz because the Periodic Timer fires at 1khz
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if (tnow - _timer < 9500) {
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return;
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}
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_timer = tnow;
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if (_state == 0) {
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_s_D2 += _spi_read_adc(); // On state 0 we read temp
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_d2_count++;
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if (_d2_count == 32) {
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// we have summed 32 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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_s_D2 >>= 1;
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_d2_count = 16;
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}
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_state++;
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_spi_write(CMD_CONVERT_D1_OSR4096); // Command to read pressure
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} else {
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_s_D1 += _spi_read_adc();
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_d1_count++;
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if (_d1_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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_s_D1 >>= 1;
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_d1_count = 64;
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}
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_state++;
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_updated = true; // New pressure reading
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if (_state == 5) {
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_spi_write(CMD_CONVERT_D2_OSR4096); // Command to read temperature
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_state = 0;
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} else {
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_spi_write(CMD_CONVERT_D1_OSR4096); // Command to read pressure
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}
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}
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}
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uint8_t AP_Baro_MS5611::read()
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{
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bool updated = _updated;
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if (updated) {
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uint32_t sD1, sD2;
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uint8_t d1count, d2count;
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// we need to disable interrupts to access
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// _s_D1 and _s_D2 as they are not atomic
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cli();
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sD1 = _s_D1; _s_D1 = 0;
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sD2 = _s_D2; _s_D2 = 0;
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d1count = _d1_count; _d1_count = 0;
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d2count = _d2_count; _d2_count = 0;
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_updated = false;
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sei();
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if (d1count != 0) {
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D1 = ((float)sD1) / d1count;
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}
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if (d2count != 0) {
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D2 = ((float)sD2) / d2count;
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}
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_pressure_samples = d1count;
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_raw_press = D1;
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_raw_temp = D2;
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}
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_calculate();
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if (updated) {
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_last_update = millis();
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}
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return updated ? 1 : 0;
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}
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// Calculate Temperature and compensated Pressure in real units (Celsius degrees*100, mbar*100).
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void AP_Baro_MS5611::_calculate()
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{
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float dT;
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float TEMP;
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float OFF;
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float SENS;
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float P;
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// Formulas from manufacturer datasheet
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// sub -20c temperature compensation is not included
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// we do the calculations using floating point
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// as this is much faster on an AVR2560, and also allows
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// us to take advantage of the averaging of D1 and D1 over
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// multiple samples, giving us more precision
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dT = D2-(((uint32_t)C5)<<8);
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TEMP = (dT * C6)/8388608;
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OFF = C2 * 65536.0 + (C4 * dT) / 128;
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SENS = C1 * 32768.0 + (C3 * dT) / 256;
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if (TEMP < 0) {
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// second order temperature compensation when under 20 degrees C
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float T2 = (dT*dT) / 0x80000000;
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float Aux = TEMP*TEMP;
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float OFF2 = 2.5*Aux;
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float SENS2 = 1.25*Aux;
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TEMP = TEMP - T2;
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OFF = OFF - OFF2;
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SENS = SENS - SENS2;
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}
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P = (D1*SENS/2097152 - OFF)/32768;
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Temp = TEMP + 2000;
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Press = P;
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}
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float AP_Baro_MS5611::get_pressure()
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{
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return Press;
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}
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float AP_Baro_MS5611::get_temperature()
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{
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// callers want the temperature in 0.1C units
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return Temp/10;
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}
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int32_t AP_Baro_MS5611::get_raw_pressure() {
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return _raw_press;
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}
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int32_t AP_Baro_MS5611::get_raw_temp() {
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return _raw_temp;
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}
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