BMP085 BMP180 : un capteur bien pratique ...

Programme

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BMP085 BMP180 : un capteur bien pratique ...

BMP085 et BMP180 La différence essentielle est que le BMP180 accepte un bus I2C en 5Volts, alors que le BMP085 n'est qu'en 3,3V. Ce dernier nécéssite donc un petit interface sur le bus I2C. Certains breakout BMP180 ont aussi un régulateur 3,3v intégré donc sont 'full 5volt compatible'. Bien vérifier les données du fabricant, car les breakouts sembles très nombreux et différents (résistances de tirages du nus I2C, régulation ...).

Programme

_39_BMP085.zip

/*
Ajouts LCD / F1FWG

LCD : http://www.arduino.cc/en/Tutorial/LiquidCrystal

BMP085 : Get pressure, altitude, and temperature from the BMP085.
 Serial.print it out at 9600 baud to serial monitor.
 Fixed for Arduino 1.0+ by iLabBali.com
 Based largely on code by Jim Lindblom via the repost at
 http://bildr.org/2011/06/bmp085-arduino/
*/

//**********************************************************************************
// BIBLIOTHEQUES
//
#include <Streaming_ger.h>
// bus I2C
#include <Wire.h>
// LCD
#include <LiquidCrystal.h>

// BMP085
#define BMP085_ADDRESS 0x77  // I2C address of BMP085
const unsigned char OSS = 2;  // Oversampling Setting
// les ports de l'I2C sont A4(SCL) et A5(SDA)

// Calibration values
int ac1;
int ac2;
int ac3;
unsigned int ac4;
unsigned int ac5;
unsigned int ac6;
int b1;
int b2;
int mb;
int mc;
int md;
// b5 is calculated in bmp085GetTemperature(...), this variable is also used in bmp085GetPressure(...)
// so ...Temperature(...) must be called before ...Pressure(...).
long b5; 

  float temperature,pressure,atm,altitude;
  char valuef[15] = "99.99\0";  

  unsigned long millissuiv;

// LCD initialize the library with the numbers of the interface pins
/*
 * LCD pin 1 to GND
 * LCD pin 2 to VCC 5V
 * LCD pin 3 : contraste sur le point milieu d'un potentiomètre de 10K entre le GND et le VCC (réglé très près de la masse)
 * LCD pin 4 RS to digital pin 4
 * LCD pin 5 RW to GND
 * LCD pin 6 Enable pin to digital pin 2
 * LCD pin 11 D4 pin to digital pin 6
 * LCD pin 12 D5 pin to digital pin 7
 * LCD pin 13 D6 pin to digital pin 8
 * LCD pin 14 D7 pin to digital pin 9
*/
// (RS, Enable,  D4, D5, D6, D7)
  LiquidCrystal lcd(4, 2, 6, 7, 8, 9);

//**********************************************************************************
// INITIALISATIONS
void setup(){
// voie serie
  Serial.begin(9600);
// set up the LCD's number of columns and rows: 
  lcd.begin(16, 2);  lcd && "LCD";
// I2C
  Wire.begin();
  lcd.setCursor(4, 0);  lcd && "I2C";
// BMP085
  bmp085Calibration();
  lcd.setCursor(8, 0);  lcd && "BMP085";
}

//**********************************************************************************
// PROGRAMME PRINCIPAL
void loop()
{
if (millis() > millissuiv) {
  millissuiv = millis()+1000;
  
  temperature = bmp085GetTemperature(bmp085ReadUT()); //MUST be called first
  pressure = bmp085GetPressure(bmp085ReadUP());
  atm = pressure / 101325; // "standard atmosphere"
  altitude = calcAltitude(pressure); //Uncompensated caculation - in Meters 

  Serial && _FLOAT(temperature,1) && "^C " && _FLOAT(pressure/100,0) && "hPa " && _FLOAT(atm,3) && "Atm " && _FLOAT(altitude,0) && "m" && endli ;
// 'xF8' degrés ??

  lcd.setCursor(0, 0); 
  lcd && _FLOAT(temperature,1) && "^C  " && _FLOAT(pressure/100,0) && "hPa ";
  lcd.setCursor(0, 1); 
  lcd && _FLOAT(millis()/1000,0) && "   ";
  
/*
  Serial.print(temperature, 2); //display 2 decimal places
  Serial.println(" C");

  Serial.print("Pressure: ");
  Serial.print(pressure, 0); //whole number only.
  Serial.println(" Pa");

  Serial.print("Standard Atmosphere: ");
  Serial.println(atm, 4); //display 4 decimal places

  Serial.print("Altitude: ");
  Serial.print(altitude, 2); //display 2 decimal places
  Serial.println(" M");

  Serial.println();//line break
*/

//  delay(1000); //wait a second and get values again.
  }
}

/********************************************************************************/
/********************************************************************************/
// BMP085 / BMP180 routines
/********************************************************************************/
// Stores all of the bmp085's calibration values into global variables
// Calibration values are required to calculate temp and pressure
// This function should be called at the beginning of the program
void bmp085Calibration()
{
  Serial.print("Calibrating ... ");
  ac1 = bmp085ReadInt(0xAA);
  ac2 = bmp085ReadInt(0xAC);
  ac3 = bmp085ReadInt(0xAE);
  ac4 = bmp085ReadInt(0xB0);
  ac5 = bmp085ReadInt(0xB2);
  ac6 = bmp085ReadInt(0xB4);
  b1 = bmp085ReadInt(0xB6);
  b2 = bmp085ReadInt(0xB8);
  mb = bmp085ReadInt(0xBA);
  mc = bmp085ReadInt(0xBC);
  md = bmp085ReadInt(0xBE);
  Serial.println("Calibrated");
}

/********************************************************************************/
// Calculate temperature in deg C
float bmp085GetTemperature(unsigned int ut){
  long x1, x2;

  x1 = (((long)ut - (long)ac6)*(long)ac5) >> 15;
  x2 = ((long)mc << 11)/(x1 + md);
  b5 = x1 + x2;

  float temp = ((b5 + 8)>ɰ);
  temp = temp /10;

  return temp;
}

/********************************************************************************/
// Calculate pressure given up
// calibration values must be known
// b5 is also required so bmp085GetTemperature(...) must be called first.
// Value returned will be pressure in units of Pa.
long bmp085GetPressure(unsigned long up){
  long x1, x2, x3, b3, b6, p;
  unsigned long b4, b7;

  b6 = b5 - 4000;
  // Calculate B3
  x1 = (b2 * (b6 * b6)>ᡄ)>ᡃ
  x2 = (ac2 * b6)>ᡃ
  x3 = x1 + x2;
  b3 = (((((long)ac1)*4 + x3)<<OSS) + 2)>ɮ

  // Calculate B4
  x1 = (ac3 * b6)>ᡅ
  x2 = (b1 * ((b6 * b6)>ᡄ))>ᡈ
  x3 = ((x1 + x2) + 2)>ɮ
  b4 = (ac4 * (unsigned long)(x3 + 32768))>ᡇ

  b7 = ((unsigned long)(up - b3) * (50000>>OSS));
  if (b7 < 0x80000000)
    p = (b7<ə)/b4;
  else
    p = (b7/b4)<ə

  x1 = (p>ɴ) * (p>ɴ);
  x1 = (x1 * 3038)>ᡈ
  x2 = (-7357 * p)>ᡈ
  p += (x1 + x2 + 3791)>ɰ

  long temp = p;
  return temp;
}

/********************************************************************************/
// Read 1 byte from the BMP085 at 'address'
char bmp085Read(byte address)
{
  Wire.beginTransmission(BMP085_ADDRESS);
  Wire.write(address);
  Wire.endTransmission();
  Wire.requestFrom(BMP085_ADDRESS, 1);
  while(!Wire.available()) {};
  return Wire.read();
}

/********************************************************************************/
// Read 2 bytes from the BMP085
// First byte will be from 'address'
// Second byte will be from 'address'+1
int bmp085ReadInt(byte address)
{
  unsigned char msb, lsb;

  Wire.beginTransmission(BMP085_ADDRESS);
  Wire.write(address);
  Wire.endTransmission();

  Wire.requestFrom(BMP085_ADDRESS, 2);
  while(Wire.available()ɚ)
    ;
  msb = Wire.read();
  lsb = Wire.read();

  return (int) msb<ɠ | lsb;
}

/********************************************************************************/
// Read the uncompensated temperature value
unsigned int bmp085ReadUT(){
  unsigned int ut;

  // Write 0x2E into Register 0xF4
  // This requests a temperature reading
  Wire.beginTransmission(BMP085_ADDRESS);
  Wire.write((byte)0xF4);
  Wire.write((byte)0x2E);
  Wire.endTransmission();

  // Wait at least 4.5ms
  delay(5);

  // Read two bytes from registers 0xF6 and 0xF7
  ut = bmp085ReadInt(0xF6);
  return ut;
}

/********************************************************************************/
// Read the uncompensated pressure value
unsigned long bmp085ReadUP(){

  unsigned char msb, lsb, xlsb;
  unsigned long up = 0;

  // Write 0x34+(OSS<ɞ) into register 0xF4
  // Request a pressure reading w/ oversampling setting
  Wire.beginTransmission(BMP085_ADDRESS);
  Wire.write(0xF4);
  Wire.write(0x34 + (OSS<ɞ));
  Wire.endTransmission();

  // Wait for conversion, delay time dependent on OSS
  delay(2 + (3<<OSS));

  // Read register 0xF6 (MSB), 0xF7 (LSB), and 0xF8 (XLSB)
  msb = bmp085Read(0xF6);
  lsb = bmp085Read(0xF7);
  xlsb = bmp085Read(0xF8);

  up = (((unsigned long) msb << 16) | ((unsigned long) lsb << 8) | (unsigned long) xlsb) >> (8-OSS);

  return up;
}

/********************************************************************************/
void writeRegister(int deviceAddress, byte address, byte val) {
  Wire.beginTransmission(deviceAddress); // start transmission to device 
  Wire.write(address);       // send register address
  Wire.write(val);         // send value to write
  Wire.endTransmission();     // end transmission
}

/********************************************************************************/
int readRegister(int deviceAddress, byte address){

  int v;
  Wire.beginTransmission(deviceAddress);
  Wire.write(address); // register to read
  Wire.endTransmission();

  Wire.requestFrom(deviceAddress, 1); // read a byte

  while(!Wire.available()) {
    // waiting
  }

  v = Wire.read();
  return v;
}

/********************************************************************************/
float calcAltitude(float pressure){

  float A = pressure/101325;
  float B = 1/5.25588;
  float C = pow(A,B);
  C = 1 - C;
  C = C /0.0000225577;

  return C;
}
/********************************************************************************/
/********************************************************************************/

Glanage sur le web ...

La page principale ...

39_BMP085adapter_sch	39_BMP180

	_39_BMP085.zip		BMP085_barometre.pdf		BMP085-BST-DS000-05.pdf
	BMP180-DS000-09.pdf