/
altitude_sketch.ino
executable file
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/
altitude_sketch.ino
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//Jake Messner and Javier Chia-Hsing Yu
//Project Defeat Icarus, 2013-2014
#include <Wire.h>
#define MPL3115A2_ADDRESS 0x60
void setup()
{
Wire.begin();
Serial.begin(9600);
MPL_begin();
setModeAltimeter();
//setModeBarometer(); // Measure pressure in Pascals from 20 to 110 kPa
setOversampleRate(4);
enableEventFlags();
setModeActive();
}
void loop()
{
float altitude = readAltitude();
Serial.print("Altitude(m):");
Serial.print(altitude, 2);
altitude = readAltitudeFt();
Serial.print(" Altitude(ft):");
Serial.print(altitude, 2);
/*float pressure = readPressure();
Serial.print(" Pressure(Pa):");
Serial.println(pressure, 2);*/
//float temperature = readTemp();
//Serial.print(" Temp(c):");
//Serial.print(temperature, 2);
float temperature = readTempF();
Serial.print(" Temp(f):");
Serial.print(temperature, 2);
Serial.println();
delay(100);
}
boolean MPL_begin()
{
if(IIC_Read(WHO_AM_I) == 196) return(true);
return(false);
}
float readAltitude()
{
while( (IIC_Read(STATUS) & (1<<2)) == 0) break;
// Read pressure registers
Wire.beginTransmission(MPL3115A2_ADDRESS);
Wire.write(OUT_P_MSB);
Wire.endTransmission(false);
Wire.requestFrom(MPL3115A2_ADDRESS, 3);
int counter = 0;
while(Wire.available() < 3)
{
if(counter++ > 100) return 0;
delay(1);
}
byte msb, csb, lsb;
msb = Wire.read();
csb = Wire.read();
lsb = Wire.read();
float tempcsb = (lsb>>4)/16.0;
float altitude = (float)( (msb << 8) | csb) + tempcsb;
return(altitude);
}
float readAltitudeFt()
{
return(readAltitude() * 3.28084);
}
float readPressure()
{
while( (IIC_Read(STATUS) & (1<<2)) == 0) break;
Wire.beginTransmission(MPL3115A2_ADDRESS);
Wire.write(OUT_P_MSB);
Wire.endTransmission(false);
Wire.requestFrom(MPL3115A2_ADDRESS, 3);
//Wait for data to become available
int counter = 0;
while(Wire.available() < 3)
{
if(counter++ > 100) return 0;
delay(1);
}
byte msb, csb, lsb;
msb = Wire.read();
csb = Wire.read();
lsb = Wire.read();
long pressure_whole = (long)msb<<16 | (long)csb<<8 | (long)lsb;
pressure_whole >>= 6;
lsb &= 0b00110000;
lsb >>= 4;
float pressure_decimal = (float)lsb/4.0;
float pressure = (float)pressure_whole + pressure_decimal;
return(pressure);
}
float readTemp()
{
while( (IIC_Read(STATUS) & (1<<1)) == 0) break;
// Read temperature
Wire.beginTransmission(MPL3115A2_ADDRESS);
Wire.write(OUT_T_MSB); // Address of data to get
Wire.endTransmission(false);
Wire.requestFrom(MPL3115A2_ADDRESS, 2);
int counter = 0;
while(Wire.available() < 2)
{
if(counter++ > 100) return 0;
delay(1);
}
byte msb, lsb;
msb = Wire.read();
lsb = Wire.read();
float templsb = (lsb>>4)/16.0;
float temperature = (float)(msb + templsb);
return(temperature);
}
float readTempF()
{
return((readTemp() * 9.0)/ 5.0 + 32.0); // Convert celsius to fahrenheit
}
//Sets the mode to Barometer
void setModeBarometer()
{
byte tempSetting = IIC_Read(CTRL_REG1);
tempSetting &= ~(1<<7);
IIC_Write(CTRL_REG1, tempSetting);
}
void setModeAltimeter()
{
byte tempSetting = IIC_Read(CTRL_REG1); //Read current settings
tempSetting |= (1<<7); //Set ALT bit
IIC_Write(CTRL_REG1, tempSetting);
}
//Puts the sensor in standby mode
void setModeStandby()
{
byte tempSetting = IIC_Read(CTRL_REG1);
tempSetting &= ~(1<<0);
IIC_Write(CTRL_REG1, tempSetting);
}
//Puts the sensor in active mode
void setModeActive()
{
byte tempSetting = IIC_Read(CTRL_REG1);
tempSetting |= (1<<0);
IIC_Write(CTRL_REG1, tempSetting);
}
void setOversampleRate(byte sampleRate)
{
if(sampleRate > 7) sampleRate = 7;
sampleRate <<= 3;
byte tempSetting = IIC_Read(CTRL_REG1);
tempSetting &= 0b11000111;
tempSetting |= sampleRate;
IIC_Write(CTRL_REG1, tempSetting);
}
void enableEventFlags()
{
IIC_Write(PT_DATA_CFG, 0x07); // Enable all three pressure and temp event flags
}
byte IIC_Read(byte regAddr)
{
Wire.beginTransmission(MPL3115A2_ADDRESS);
Wire.write(regAddr);
Wire.endTransmission(false);
Wire.requestFrom(MPL3115A2_ADDRESS, 1);
return Wire.read();
}
void IIC_Write(byte regAddr, byte value)
{
Wire.beginTransmission(MPL3115A2_ADDRESS);
Wire.write(regAddr);
Wire.write(value);
Wire.endTransmission(true);
}