Arduino temperature, humidity, and pressure monitor interfaced with a PICAXE OLED display.

THPrev4aextendedwvoltageOLED.pde

//This code is for Arduino 0023 or less only.  
/* The library to run the OLED display comes from here: 

https://www.adafruit.com/products/823

The library was made for Arduino 1.0 but it had to be modified to work with Arduino 0023 or less.  

*/


// Read temperature/humidity/pressure from sensors and display on 16x2 Character LCD screen
#include <Adafruit_CharacterOLED.h>
#include <Sensirion.h>
#include <Wire.h>

#define sensorDataPin 3 //SHT15 Data pin
#define sensorClockPin 4 //SHT SCK pin

#define BMP085_ADDRESS 0x77

const unsigned char OSS = 1;  // Oversampling Setting (default in this code is 0)

Adafruit_CharacterOLED lcd(6, 7, 8, 9, 10, 11, 12);

float temperature;
float humidity;
float dewpoint;

Sensirion tempSensor = Sensirion(sensorDataPin, sensorClockPin);



// Calibration values for BMP085
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; 

void setup() {
  pinMode(2, OUTPUT);
  pinMode(13, OUTPUT);
  Wire.begin();
  lcd.begin(16,2);
  bmp085Calibration();
  lcd.setCursor(0,0);
  lcd.print("Temp/RH/Press");
  lcd.setCursor(0,1);
  lcd.print("Monitor Rev 2.2b");
  delay(5000);
  lcd.clear();
}

void loop() {
  // get the temp/humidity
  tempSensor.measure(&temperature, &humidity, &dewpoint);
  
  lcd.setCursor(0,0);
  lcd.print("T1");
  lcd.setCursor(3,0);
  lcd.print(convertToFahrenheit(temperature), 1);
  
  lcd.setCursor(8,0);
  lcd.print("RH");
  lcd.setCursor(11,0);
  lcd.print(humidity,2);
  
  if(humidity>=50.0){
    digitalWrite(2, HIGH);
  }else if(humidity<=48.0){
    digitalWrite(2, LOW);
  }
  
  float temperature1 = bmp085GetTemperature(bmp085ReadUT()); //MUST be called first
  float pressure = bmp085GetPressure(bmp085ReadUP());
  //float atm = pressure / 101325; // "standard atmosphere"
  //float altitude = calcAltitude(pressure); //Uncompensated caculation - in Meters
  //Altitude measurement is not utilized. 
  
  
  lcd.setCursor(0,1);
  lcd.print("T2");
  lcd.setCursor(3,1);
  float fahrenheit;
  fahrenheit=(((9.0 / 5.0) * temperature1) + 32.0);
  lcd.print(fahrenheit, 1); //display 2 decimal places
  
  
  lcd.setCursor(8,1);
  lcd.print("PS");
  float inpress;
  inpress=(pressure*0.000295299830714); //Converting Pa to inHg
  lcd.setCursor(11,1);
  lcd.print(inpress, 2); //whole number only (if displaying in Pa).
  //lcd.print("Pa");  ***In this case value is to 2 decimal places***  
 
 float voltage=(analogRead(0)*0.004882812);
 if(voltage>=3.77){
   digitalWrite(13, LOW);
 }else if(voltage<=3.75){
   digitalWrite(13, HIGH);
 }
 
 
  delay(6500); //Delay must be high as SHT15 needs to stabilize readings
              //(Humidity needs to be temperature compensated)
              //Sensor cannot be active than more than 10% of the time
}


// Convert celsius to fahrenheit
float convertToFahrenheit(float c) {
  return ((9.0 / 5.0) * c) + 32.0;
}

void bmp085Calibration()
{
  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);
}

// 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)>>4);
  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)>>12)>>11;
  x2 = (ac2 * b6)>>11;
  x3 = x1 + x2;
  b3 = (((((long)ac1)*4 + x3)<<OSS) + 2)>>2;

  // Calculate B4
  x1 = (ac3 * b6)>>13;
  x2 = (b1 * ((b6 * b6)>>12))>>16;
  x3 = ((x1 + x2) + 2)>>2;
  b4 = (ac4 * (unsigned long)(x3 + 32768))>>15;

  b7 = ((unsigned long)(up - b3) * (50000>>OSS));
  if (b7 < 0x80000000)
    p = (b7<<1)/b4;
  else
    p = (b7/b4)<<1;

  x1 = (p>>8) * (p>>8);
  x1 = (x1 * 3038)>>16;
  x2 = (-7357 * p)>>16;
  p += (x1 + x2 + 3791)>>4;

  long temp = p;
  return temp;
}

// Read 1 byte from the BMP085 at 'address'
char bmp085Read(unsigned char address)
{
  unsigned char data;

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

  Wire.requestFrom(BMP085_ADDRESS, 1);
  while(!Wire.available())
    ;

  return Wire.receive();
}

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

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

  Wire.requestFrom(BMP085_ADDRESS, 2);
  while(Wire.available()<2)
    ;
  msb = Wire.receive();
  lsb = Wire.receive();

  return (int) msb<<8 | 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.send(0xF4);
  Wire.send(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<<6) into register 0xF4
  // Request a pressure reading w/ oversampling setting
  Wire.beginTransmission(BMP085_ADDRESS);
  Wire.send(0xF4);
  Wire.send(0x34 + (OSS<<6));
  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.send(address);       // send register address
  Wire.send(val);         // send value to write
  Wire.endTransmission();     // end transmission
}

int readRegister(int deviceAddress, byte address){

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

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

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

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