You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
248 lines
6.6 KiB
248 lines
6.6 KiB
/* |
|
APM_MS5611.cpp - Arduino Library for MS5611-01BA01 absolute pressure sensor |
|
Code by Jose Julio, Pat Hickey and Jordi Muñoz. DIYDrones.com |
|
|
|
This library is free software; you can redistribute it and/or |
|
modify it under the terms of the GNU Lesser General Public |
|
License as published by the Free Software Foundation; either |
|
version 2.1 of the License, or (at your option) any later version. |
|
|
|
Sensor is conected to standard SPI port |
|
Chip Select pin: Analog2 (provisional until Jordi defines the pin)!! |
|
|
|
Variables: |
|
Temp : Calculated temperature (in Celsius degrees * 100) |
|
Press : Calculated pressure (in mbar units * 100) |
|
|
|
|
|
Methods: |
|
init() : Initialization and sensor reset |
|
read() : Read sensor data and calculate Temperature, Pressure and Altitude |
|
This function is optimized so the main host don´t need to wait |
|
You can call this function in your main loop |
|
Maximun data output frequency 100Hz |
|
It returns a 1 if there are new data. |
|
get_pressure() : return pressure in mbar*100 units |
|
get_temperature() : return temperature in celsius degrees*100 units |
|
get_altitude() : return altitude in meters |
|
|
|
Internal functions: |
|
calculate() : Calculate Temperature and Pressure (temperature compensated) in real units |
|
|
|
|
|
*/ |
|
|
|
#include <SPI.h> |
|
#include "AP_Baro_MS5611.h" |
|
|
|
|
|
/* on APM v.24 MS5661_CS is PG1 (Arduino pin 40) */ |
|
#define MS5611_CS 40 |
|
|
|
#define CMD_MS5611_RESET 0x1E |
|
#define CMD_MS5611_PROM_Setup 0xA0 |
|
#define CMD_MS5611_PROM_C1 0xA2 |
|
#define CMD_MS5611_PROM_C2 0xA4 |
|
#define CMD_MS5611_PROM_C3 0xA6 |
|
#define CMD_MS5611_PROM_C4 0xA8 |
|
#define CMD_MS5611_PROM_C5 0xAA |
|
#define CMD_MS5611_PROM_C6 0xAC |
|
#define CMD_MS5611_PROM_CRC 0xAE |
|
#define CMD_CONVERT_D1_OSR4096 0x48 // Maximun resolution |
|
#define CMD_CONVERT_D2_OSR4096 0x58 // Maximun resolution |
|
|
|
|
|
uint8_t MS5611_SPI_read(byte reg) |
|
{ |
|
byte dump; |
|
uint8_t return_value; |
|
byte addr = reg; // | 0x80; // Set most significant bit |
|
digitalWrite(MS5611_CS, LOW); |
|
dump = SPI.transfer(addr); |
|
return_value = SPI.transfer(0); |
|
digitalWrite(MS5611_CS, HIGH); |
|
return(return_value); |
|
} |
|
|
|
uint16_t MS5611_SPI_read_16bits(byte reg) |
|
{ |
|
byte dump,byteH,byteL; |
|
uint16_t return_value; |
|
byte addr = reg; // | 0x80; // Set most significant bit |
|
digitalWrite(MS5611_CS, LOW); |
|
dump = SPI.transfer(addr); |
|
byteH = SPI.transfer(0); |
|
byteL = SPI.transfer(0); |
|
digitalWrite(MS5611_CS, HIGH); |
|
return_value = ((uint16_t)byteH<<8) | (byteL); |
|
return(return_value); |
|
} |
|
|
|
uint32_t MS5611_SPI_read_ADC() |
|
{ |
|
byte dump,byteH,byteM,byteL; |
|
uint32_t return_value; |
|
byte addr = 0x00; |
|
digitalWrite(MS5611_CS, LOW); |
|
dump = SPI.transfer(addr); |
|
byteH = SPI.transfer(0); |
|
byteM = SPI.transfer(0); |
|
byteL = SPI.transfer(0); |
|
digitalWrite(MS5611_CS, HIGH); |
|
return_value = (((uint32_t)byteH)<<16) | (((uint32_t)byteM)<<8) | (byteL); |
|
return(return_value); |
|
} |
|
|
|
|
|
void MS5611_SPI_write(byte reg) |
|
{ |
|
byte dump; |
|
digitalWrite(MS5611_CS, LOW); |
|
dump = SPI.transfer(reg); |
|
digitalWrite(MS5611_CS, HIGH); |
|
} |
|
|
|
// The conversion proccess takes 8.2ms since the command |
|
uint8_t AP_Baro_MS5611::MS5611_Ready() |
|
{ |
|
if ((millis()-MS5611_timer)>10) // wait for more than 10ms |
|
return(1); |
|
else |
|
return(0); |
|
} |
|
|
|
// Public Methods ////////////////////////////////////////////////////////////// |
|
// SPI should be initialized externally |
|
void AP_Baro_MS5611::init( AP_PeriodicProcess *scheduler ) |
|
{ |
|
pinMode(MS5611_CS, OUTPUT); // Chip select Pin |
|
digitalWrite(MS5611_CS, HIGH); |
|
delay(1); |
|
|
|
MS5611_SPI_write(CMD_MS5611_RESET); |
|
delay(4); |
|
|
|
// We read the factory calibration |
|
C1 = MS5611_SPI_read_16bits(CMD_MS5611_PROM_C1); |
|
C2 = MS5611_SPI_read_16bits(CMD_MS5611_PROM_C2); |
|
C3 = MS5611_SPI_read_16bits(CMD_MS5611_PROM_C3); |
|
C4 = MS5611_SPI_read_16bits(CMD_MS5611_PROM_C4); |
|
C5 = MS5611_SPI_read_16bits(CMD_MS5611_PROM_C5); |
|
C6 = MS5611_SPI_read_16bits(CMD_MS5611_PROM_C6); |
|
|
|
|
|
//Send a command to read Temp first |
|
MS5611_SPI_write(CMD_CONVERT_D2_OSR4096); |
|
MS5611_timer = millis(); |
|
MS5611_State = 1; |
|
Temp=0; |
|
Press=0; |
|
} |
|
|
|
|
|
// Read the sensor. This is a state machine |
|
// We read one time Temperature (state=1) and then 4 times Pressure (states 2-5) |
|
// temperature does not change so quickly... |
|
uint8_t AP_Baro_MS5611::read() |
|
{ |
|
uint8_t result = 0; |
|
|
|
if (MS5611_State == 1){ |
|
if (MS5611_Ready()){ |
|
D2=MS5611_SPI_read_ADC(); // On state 1 we read temp |
|
_raw_temp = D2; |
|
MS5611_State++; |
|
MS5611_SPI_write(CMD_CONVERT_D1_OSR4096); // Command to read pressure |
|
MS5611_timer = millis(); |
|
} |
|
}else{ |
|
if (MS5611_State == 5){ |
|
if (MS5611_Ready()){ |
|
D1=MS5611_SPI_read_ADC(); |
|
_raw_press = D1; |
|
calculate(); |
|
MS5611_State = 1; // Start again from state = 1 |
|
MS5611_SPI_write(CMD_CONVERT_D2_OSR4096); // Command to read temperature |
|
MS5611_timer = millis(); |
|
result = 1; // New pressure reading |
|
} |
|
}else{ |
|
if (MS5611_Ready()){ |
|
D1=MS5611_SPI_read_ADC(); |
|
_raw_press = D1; |
|
calculate(); |
|
MS5611_State++; |
|
MS5611_SPI_write(CMD_CONVERT_D1_OSR4096); // Command to read pressure |
|
MS5611_timer = millis(); |
|
result = 1; // New pressure reading |
|
} |
|
} |
|
} |
|
return(result); |
|
} |
|
|
|
// Calculate Temperature and compensated Pressure in real units (Celsius degrees*100, mbar*100). |
|
void AP_Baro_MS5611::calculate() |
|
{ |
|
int32_t dT; |
|
long long TEMP; // 64 bits |
|
long long OFF; |
|
long long SENS; |
|
long long P; |
|
|
|
// Formulas from manufacturer datasheet |
|
// TODO: optimization with shift operations... (shift operations works well on 64 bits variables?) |
|
// We define parameters as 64 bits to prevent overflow on operations |
|
dT = D2-((long)C5*256); |
|
TEMP = 2000 + ((long long)dT * C6)/8388608; |
|
OFF = (long long)C2 * 65536 + ((long long)C4 * dT ) / 128; |
|
SENS = (long long)C1 * 32768 + ((long long)C3 * dT) / 256; |
|
|
|
/* |
|
if (TEMP < 2000){ // second order temperature compensation |
|
long long T2 = (long long)dT*dT / 2147483648; |
|
long long Aux_64 = (TEMP-2000)*(TEMP-2000); |
|
long long OFF2 = 5*Aux_64/2; |
|
long long SENS2 = 5*Aux_64/4; |
|
TEMP = TEMP - T2; |
|
OFF = OFF - OFF2; |
|
SENS = SENS - SENS2; |
|
} |
|
*/ |
|
P = (D1*SENS/2097152 - OFF)/32768; |
|
Temp = TEMP; |
|
Press = P; |
|
} |
|
|
|
int32_t AP_Baro_MS5611::get_pressure() |
|
{ |
|
return(Press); |
|
} |
|
|
|
int16_t AP_Baro_MS5611::get_temperature() |
|
{ |
|
return(Temp); |
|
} |
|
|
|
// Return altitude using the standard 1013.25 mbar at sea level reference |
|
float AP_Baro_MS5611::get_altitude() |
|
{ |
|
float tmp_float; |
|
float Altitude; |
|
|
|
tmp_float = (Press / 101325.0); |
|
tmp_float = pow(tmp_float, 0.190295); |
|
Altitude = 44330 * (1.0 - tmp_float); |
|
|
|
return (Altitude); |
|
} |
|
|
|
int32_t AP_Baro_MS5611::get_raw_pressure() { |
|
return _raw_press; |
|
} |
|
|
|
int32_t AP_Baro_MS5611::get_raw_temp() { |
|
return _raw_temp; |
|
} |
|
|
|
|
|
|