/* APM_BMP085.cpp - Arduino Library for BMP085 absolute pressure sensor Code by Jordi Muņoz and Jose Julio. 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 I2C port Sensor End of Conversion (EOC) pin is PC7 (30) Variables: RawTemp : Raw temperature data RawPress : Raw pressure data Temp : Calculated temperature (in 0.1ēC units) Press : Calculated pressure (in Pa units) Methods: Init() : Initialization of I2C and read sensor calibration data Read() : Read sensor data and calculate Temperature and Pressure This function is optimized so the main host don´t need to wait You can call this function in your main loop It returns a 1 if there are new data. Internal functions: Command_ReadTemp(): Send commando to read temperature Command_ReadPress(): Send commando to read Pressure ReadTemp() : Read temp register ReadPress() : Read press register Calculate() : Calculate Temperature and Pressure in real units */ extern "C" { // AVR LibC Includes #include #include #include "WConstants.h" } #include #include "APM_BMP085.h" #define BMP085_ADDRESS 0x77 //(0xEE >> 1) #define BMP085_EOC 30 // End of conversion pin PC7 // Constructors //////////////////////////////////////////////////////////////// APM_BMP085_Class::APM_BMP085_Class() { } // Public Methods ////////////////////////////////////////////////////////////// void APM_BMP085_Class::Init(int initialiseWireLib) { unsigned char tmp; byte buff[22]; int i=0; pinMode(BMP085_EOC,INPUT); // End Of Conversion (PC7) input if( initialiseWireLib != 0 ) Wire.begin(); oss = 3; // Over Sampling setting 3 = High resolution BMP085_State = 0; // Initial state // We read the calibration data registers Wire.beginTransmission(BMP085_ADDRESS); Wire.send(0xAA); Wire.endTransmission(); Wire.requestFrom(BMP085_ADDRESS, 22); //Wire.endTransmission(); while(Wire.available()) { buff[i] = Wire.receive(); // receive one byte i++; } ac1 = ((int)buff[0] << 8) | buff[1]; ac2 = ((int)buff[2] << 8) | buff[3]; ac3 = ((int)buff[4] << 8) | buff[5]; ac4 = ((int)buff[6] << 8) | buff[7]; ac5 = ((int)buff[8] << 8) | buff[9]; ac6 = ((int)buff[10] << 8) | buff[11]; b1 = ((int)buff[12] << 8) | buff[13]; b2 = ((int)buff[14] << 8) | buff[15]; mb = ((int)buff[16] << 8) | buff[17]; mc = ((int)buff[18] << 8) | buff[19]; md = ((int)buff[20] << 8) | buff[21]; //Send a command to read Temp Command_ReadTemp(); BMP085_State=1; } // Read the sensor. This is a state machine // We read one time Temperature (state=1) and then 4 times Pressure (states 2-5) uint8_t APM_BMP085_Class::Read() { uint8_t result=0; if (BMP085_State==1) { if (digitalRead(BMP085_EOC)) { ReadTemp(); // On state 1 we read temp BMP085_State++; Command_ReadPress(); } } else { if (BMP085_State==5) { if (digitalRead(BMP085_EOC)) { ReadPress(); Calculate(); BMP085_State = 1; // Start again from state=1 Command_ReadTemp(); // Read Temp result=1; // New pressure reading } } else { if (digitalRead(BMP085_EOC)) { ReadPress(); Calculate(); BMP085_State++; Command_ReadPress(); result=1; // New pressure reading } } } return(result); } // Send command to Read Pressure void APM_BMP085_Class::Command_ReadPress() { Wire.beginTransmission(BMP085_ADDRESS); Wire.send(0xF4); Wire.send(0x34+(oss<<6)); //write_register(0xF4,0x34+(oversampling_setting<<6)); Wire.endTransmission(); } // Read Raw Pressure values void APM_BMP085_Class::ReadPress() { byte msb; byte lsb; byte xlsb; Wire.beginTransmission(BMP085_ADDRESS); Wire.send(0xF6); Wire.endTransmission(); Wire.requestFrom(BMP085_ADDRESS, 3); // read a byte while(!Wire.available()) { // waiting } msb = Wire.receive(); while(!Wire.available()) { // waiting } lsb = Wire.receive(); while(!Wire.available()) { // waiting } xlsb = Wire.receive(); RawPress = (((long)msb<<16) | ((long)lsb<<8) | ((long)xlsb)) >> (8-oss); } // Send Command to Read Temperature void APM_BMP085_Class::Command_ReadTemp() { Wire.beginTransmission(BMP085_ADDRESS); Wire.send(0xF4); Wire.send(0x2E); Wire.endTransmission(); } // Read Raw Temperature values void APM_BMP085_Class::ReadTemp() { byte tmp; Wire.beginTransmission(BMP085_ADDRESS); Wire.send(0xF6); Wire.endTransmission(); Wire.beginTransmission(BMP085_ADDRESS); Wire.requestFrom(BMP085_ADDRESS,2); while(!Wire.available()); // wait RawTemp = Wire.receive(); while(!Wire.available()); // wait tmp = Wire.receive(); RawTemp = RawTemp<<8 | tmp; } // Calculate Temperature and Pressure in real units. void APM_BMP085_Class::Calculate() { long x1, x2, x3, b3, b5, b6, p; unsigned long b4, b7; int32_t tmp; // See Datasheet page 13 for this formulas // Based also on Jee Labs BMP085 example code. Thanks for share. // Temperature calculations x1 = ((long)RawTemp - ac6) * ac5 >> 15; x2 = ((long) mc << 11) / (x1 + md); b5 = x1 + x2; Temp = (b5 + 8) >> 4; // Pressure calculations b6 = b5 - 4000; x1 = (b2 * (b6 * b6 >> 12)) >> 11; x2 = ac2 * b6 >> 11; x3 = x1 + x2; //b3 = (((int32_t) ac1 * 4 + x3)<> 2; // BAD //b3 = ((int32_t) ac1 * 4 + x3 + 2) >> 2; //OK for oss=0 tmp = ac1; tmp = (tmp*4 + x3)<> 13; x2 = (b1 * (b6 * b6 >> 12)) >> 16; x3 = ((x1 + x2) + 2) >> 2; b4 = (ac4 * (uint32_t) (x3 + 32768)) >> 15; b7 = ((uint32_t) RawPress - b3) * (50000 >> oss); p = b7 < 0x80000000 ? (b7 * 2) / b4 : (b7 / b4) * 2; x1 = (p >> 8) * (p >> 8); x1 = (x1 * 3038) >> 16; x2 = (-7357 * p) >> 16; Press = p + ((x1 + x2 + 3791) >> 4); } // Constructors //////////////////////////////////////////////////////////////// APM_BMP085_HIL_Class::APM_BMP085_HIL_Class() { } // Public Methods ////////////////////////////////////////////////////////////// void APM_BMP085_HIL_Class::Init(int initialiseWireLib) { BMP085_State=1; } // Read the sensor. This is a state machine // We read one time Temperature (state=1) and then 4 times Pressure (states 2-5) uint8_t APM_BMP085_HIL_Class::Read() { uint8_t result=0; if (BMP085_State==1) { BMP085_State++; } else { if (BMP085_State==5) { BMP085_State = 1; // Start again from state=1 result=1; // New pressure reading } else { BMP085_State++; result=1; // New pressure reading } } return(result); } void APM_BMP085_HIL_Class::setHIL(float _Temp, float _Press) { // TODO: map floats to raw Temp = _Temp; Press = _Press; }