Category Archives: code

BMP085 with Arduino (tested & working)

I tested & corrected and this code really works.


// BMP08 with Arduino

// DANGER: The BMP08 accepts 1.8 to 3.6 Volts – so no chance to connect it directly to 5 Volts.

// Connect VCC to VCC and GND to GND, SCL goes to analogue pin 5, SDA to analogue pin4.
// Notice! Sparkfun breakoutboard contains already 4.7K pull ups,
// If not using pre-built pull-ups:
// --> Add some pull up resistors (1K to 20K, most often something like 4.7K) between SDA, SCL and VCC finishes the setup.

// References: http://interactive-matter.org/2009/12/arduino-barometric-pressure-sensor-bmp085/ and http://news.jeelabs.org/2009/02/19/hooking-up-a-bmp085-sensor/
// Specification: http://www.bosch-sensortec.com/content/language1/downloads/BST-BMP085-DS000-05.pdf
// SparkFun breakout board: http://www.sparkfun.com/commerce/product_info.php?products_id=9694

#include "Wire.h"

#define I2C_ADDRESS 0x77

const unsigned char oversampling_setting = 3; //oversamplig for measurement
const unsigned char pressure_waittime[4] = { 5, 8, 14, 26 };

//just taken from the BMP085 datasheet
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;

void setup()
{
Serial.begin(9600); // start serial for output
Serial.println("Setting up BMP085");
Wire.begin();
bmp085_get_cal_data();
}
void bmp085_read_temperature_and_pressure(int& temperature, long& pressure);
void loop()
{
int temperature = 0;
long pressure = 0;

bmp085_read_temperature_and_pressure(&temperature,&pressure);
Serial.print(temperature,DEC);
Serial.print(" ");
Serial.print(pressure,DEC);
Serial.println();
delay(100);
}

void bmp085_read_temperature_and_pressure(int* temperature, long* pressure) {
int ut= bmp085_read_ut();
long up = bmp085_read_up();
long x1, x2, x3, b3, b5, b6, p;
unsigned long b4, b7;

//calculate the temperature
x1 = ((long)ut - ac6) * ac5 >> 15;
x2 = ((long) mc << 11) / (x1 + md);
b5 = x1 + x2;
*temperature = (b5 + 8) >> 4;

//calculate the pressure
b6 = b5 - 4000;
x1 = (b2 * (b6 * b6 >> 12)) >> 11;
x2 = ac2 * b6 >> 11;
x3 = x1 + x2;

//b3 = (((int32_t) ac1 * 4 + x3)<> 2;

if (oversampling_setting == 3) b3 = ((int32_t) ac1 * 4 + x3 + 2) << 1;
if (oversampling_setting == 2) b3 = ((int32_t) ac1 * 4 + x3 + 2);
if (oversampling_setting == 1) b3 = ((int32_t) ac1 * 4 + x3 + 2) >> 1;
if (oversampling_setting == 0) b3 = ((int32_t) ac1 * 4 + x3 + 2) >> 2;

x1 = ac3 * b6 >> 13;
x2 = (b1 * (b6 * b6 >> 12)) >> 16;
x3 = ((x1 + x2) + 2) >> 2;
b4 = (ac4 * (uint32_t) (x3 + 32768)) >> 15;
b7 = ((uint32_t) up - b3) * (50000 >> oversampling_setting);
p = b7 < 0x80000000 ? (b7 * 2) / b4 : (b7 / b4) * 2;

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

}

unsigned int bmp085_read_ut() {
write_register(0xf4,0x2e);
delay(5); //longer than 4.5 ms
return read_int_register(0xf6);
}

void bmp085_get_cal_data() {
Serial.println("Reading Calibration Data");
ac1 = read_int_register(0xAA);
Serial.print("AC1: ");
Serial.println(ac1,DEC);
ac2 = read_int_register(0xAC);
Serial.print("AC2: ");
Serial.println(ac2,DEC);
ac3 = read_int_register(0xAE);
Serial.print("AC3: ");
Serial.println(ac3,DEC);
ac4 = read_int_register(0xB0);
Serial.print("AC4: ");
Serial.println(ac4,DEC);
ac5 = read_int_register(0xB2);
Serial.print("AC5: ");
Serial.println(ac5,DEC);
ac6 = read_int_register(0xB4);
Serial.print("AC6: ");
Serial.println(ac6,DEC);
b1 = read_int_register(0xB6);
Serial.print("B1: ");
Serial.println(b1,DEC);
b2 = read_int_register(0xB8);
Serial.print("B2: ");
Serial.println(b1,DEC);
mb = read_int_register(0xBA);
Serial.print("MB: ");
Serial.println(mb,DEC);
mc = read_int_register(0xBC);
Serial.print("MC: ");
Serial.println(mc,DEC);
md = read_int_register(0xBE);
Serial.print("MD: ");
Serial.println(md,DEC);
}

long bmp085_read_up() {
write_register(0xf4,0x34+(oversampling_setting<<6));
delay(pressure_waittime[oversampling_setting]);

unsigned char msb, lsb, xlsb;
Wire.beginTransmission(I2C_ADDRESS);
Wire.send(0xf6); // register to read
Wire.endTransmission();

Wire.requestFrom(I2C_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();
return (((long)msb<<16) | ((long)lsb<<8) | ((long)xlsb)) >>(8-oversampling_setting);
}

void write_register(unsigned char r, unsigned char v)
{
Wire.beginTransmission(I2C_ADDRESS);
Wire.send(r);
Wire.send(v);
Wire.endTransmission();
}

char read_register(unsigned char r)
{
unsigned char v;
Wire.beginTransmission(I2C_ADDRESS);
Wire.send(r); // register to read
Wire.endTransmission();

Wire.requestFrom(I2C_ADDRESS, 1); // read a byte
while(!Wire.available()) {
// waiting
}
v = Wire.receive();
return v;
}

int read_int_register(unsigned char r)
{
unsigned char msb, lsb;
Wire.beginTransmission(I2C_ADDRESS);
Wire.send(r); // register to read
Wire.endTransmission();

Wire.requestFrom(I2C_ADDRESS, 2); // read a byte
while(!Wire.available()) {
// waiting
}
msb = Wire.receive();
while(!Wire.available()) {
// waiting
}
lsb = Wire.receive();
return (((int)msb<<8) | ((int)lsb));
}

Links: http://sensorapp.net/?p=278

How to remove the gloss / glare / white area from iPhone app icon?

To remove the gloss / glare / white area from iPhone app icon that iPhone adds automatically – go to the Xcode and open up the App’s Info.plist. On right side you see list like button. Press that and you’ll get new row with selectable property name. From there pick the “Icon already includes gloss..” and check the checkbox.

So in short: it’s a property in the App info.plist.

Working MD5 for Objective-C

  1.  
  2.  
  3. #import <CommonCrypto/CommonDigest.h>
  4.  
  5.  
  6. NSString * md5( NSString *str )
  7. {
  8.  
  9. const char *cStr = [str UTF8String];
  10.  
  11. unsigned char result[CC_MD5_DIGEST_LENGTH];
  12.  
  13. CC_MD5( cStr, strlen(cStr), result );
  14.  
  15. return [NSString stringWithFormat: @"%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X",
  16. result[0], result[1],
  17. result[2], result[3],
  18. result[4], result[5],
  19. result[6], result[7],
  20. result[8], result[9],
  21. result[10], result[11],
  22. result[12], result[13],
  23. result[14], result[15]];
  24.  
  25. }
  26.  
  27.  

Calculating distance in Objective-C

Returns distance in meters between to coordinates.

  1.  
  1. float calcDistance(float lat1, float lon1, float lat2,float lon2)
  2. {
  3.         float R = 6371; // km
  4.         float dLat = deg2rad((lat2-lat1));
  5.         float dLon = deg2rad((lon2-lon1));
  6.         float a = sin(dLat/2.0) *
  7. sin(dLat/2.0)+cos(deg2rad(lat1))*
  8. cos(deg2rad(lat2))*sin(dLon/2.0)*sin(dLon/2.0);
  9.         float c = 2.0 * atan2(sqrt(a), sqrt(1-a));
  10.         float d = R * c;
  11.  
  12.         return d*1000;
  13. }