mirror of https://github.com/ArduPilot/ardupilot
249 lines
6.6 KiB
C++
249 lines
6.6 KiB
C++
/*
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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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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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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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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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Methods:
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init() : Initialization and sensor reset
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read() : Read sensor data and calculate Temperature, Pressure and Altitude
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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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Maximun data output frequency 100Hz
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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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get_altitude() : return altitude in meters
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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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#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 // Maximun resolution
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#define CMD_CONVERT_D2_OSR4096 0x58 // Maximun resolution
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uint8_t MS5611_SPI_read(byte reg)
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{
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byte dump;
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uint8_t return_value;
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byte addr = reg; // | 0x80; // Set most significant bit
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digitalWrite(MS5611_CS, LOW);
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dump = SPI.transfer(addr);
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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 MS5611_SPI_read_16bits(byte reg)
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{
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byte dump,byteH,byteL;
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uint16_t return_value;
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byte addr = reg; // | 0x80; // Set most significant bit
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digitalWrite(MS5611_CS, LOW);
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dump = SPI.transfer(addr);
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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 MS5611_SPI_read_ADC()
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{
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byte dump,byteH,byteM,byteL;
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uint32_t return_value;
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byte addr = 0x00;
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digitalWrite(MS5611_CS, LOW);
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dump = SPI.transfer(addr);
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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 MS5611_SPI_write(byte reg)
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{
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byte dump;
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digitalWrite(MS5611_CS, LOW);
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dump = SPI.transfer(reg);
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digitalWrite(MS5611_CS, HIGH);
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}
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// The conversion proccess takes 8.2ms since the command
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uint8_t AP_Baro_MS5611::MS5611_Ready()
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{
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if ((millis()-MS5611_timer)>10) // wait for more than 10ms
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return(1);
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else
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return(0);
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}
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// Public Methods //////////////////////////////////////////////////////////////
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// SPI should be initialized externally
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void AP_Baro_MS5611::init( AP_PeriodicProcess *scheduler )
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{
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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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MS5611_SPI_write(CMD_MS5611_RESET);
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delay(4);
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// We read the factory calibration
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C1 = MS5611_SPI_read_16bits(CMD_MS5611_PROM_C1);
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C2 = MS5611_SPI_read_16bits(CMD_MS5611_PROM_C2);
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C3 = MS5611_SPI_read_16bits(CMD_MS5611_PROM_C3);
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C4 = MS5611_SPI_read_16bits(CMD_MS5611_PROM_C4);
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C5 = MS5611_SPI_read_16bits(CMD_MS5611_PROM_C5);
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C6 = MS5611_SPI_read_16bits(CMD_MS5611_PROM_C6);
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//Send a command to read Temp first
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MS5611_SPI_write(CMD_CONVERT_D2_OSR4096);
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MS5611_timer = millis();
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MS5611_State = 1;
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Temp=0;
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Press=0;
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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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uint8_t AP_Baro_MS5611::read()
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{
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uint8_t result = 0;
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if (MS5611_State == 1){
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if (MS5611_Ready()){
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D2=MS5611_SPI_read_ADC(); // On state 1 we read temp
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_raw_temp = D2;
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MS5611_State++;
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MS5611_SPI_write(CMD_CONVERT_D1_OSR4096); // Command to read pressure
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MS5611_timer = millis();
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}
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}else{
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if (MS5611_State == 5){
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if (MS5611_Ready()){
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D1=MS5611_SPI_read_ADC();
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_raw_press = D1;
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calculate();
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MS5611_State = 1; // Start again from state = 1
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MS5611_SPI_write(CMD_CONVERT_D2_OSR4096); // Command to read temperature
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MS5611_timer = millis();
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result = 1; // New pressure reading
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}
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}else{
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if (MS5611_Ready()){
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D1=MS5611_SPI_read_ADC();
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_raw_press = D1;
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calculate();
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MS5611_State++;
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MS5611_SPI_write(CMD_CONVERT_D1_OSR4096); // Command to read pressure
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MS5611_timer = millis();
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result = 1; // New pressure reading
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}
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}
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}
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return(result);
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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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int32_t dT;
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long long TEMP; // 64 bits
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long long OFF;
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long long SENS;
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long long P;
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// Formulas from manufacturer datasheet
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// TODO: optimization with shift operations... (shift operations works well on 64 bits variables?)
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// We define parameters as 64 bits to prevent overflow on operations
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dT = D2-((long)C5*256);
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TEMP = 2000 + ((long long)dT * C6)/8388608;
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OFF = (long long)C2 * 65536 + ((long long)C4 * dT ) / 128;
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SENS = (long long)C1 * 32768 + ((long long)C3 * dT) / 256;
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/*
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if (TEMP < 2000){ // second order temperature compensation
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long long T2 = (long long)dT*dT / 2147483648;
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long long Aux_64 = (TEMP-2000)*(TEMP-2000);
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long long OFF2 = 5*Aux_64/2;
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long long SENS2 = 5*Aux_64/4;
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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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*/
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P = (D1*SENS/2097152 - OFF)/32768;
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Temp = TEMP;
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Press = P;
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}
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int32_t AP_Baro_MS5611::get_pressure()
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{
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return(Press);
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}
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int16_t AP_Baro_MS5611::get_temperature()
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{
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return(Temp);
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}
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// Return altitude using the standard 1013.25 mbar at sea level reference
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float AP_Baro_MS5611::get_altitude()
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{
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float tmp_float;
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float Altitude;
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tmp_float = (Press / 101325.0);
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tmp_float = pow(tmp_float, 0.190295);
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Altitude = 44330 * (1.0 - tmp_float);
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return (Altitude);
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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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