Diff: main.cpp

Revision:

0:9c929de0a051

Child:

1:2935199329b2

diff -r 000000000000 -r 9c929de0a051 main.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Fri Oct 05 08:03:52 2012 +0000
@@ -0,0 +1,208 @@
+/*
+*
+*
+*
+* 1.8 - 3.6V (Vdd)
+* 1.62 - 3.6 (Vddio)
+*
+*
+*Altitude = 44330*(1-(p/p0)^(1/5.255))
+*   set p0 to sealevel pressure
+* delta p = 1hPa = 8.43m at sea level
+*
+*/
+
+/*
+*Pinout:
+*pin9  = SDA
+*pin10 = SCL
+*pin11 = XCLR (digital out; active low; Resets sensor)
+*pin12 = EOC ("end of conversation"; signal when conversion finished)
+*
+*
+*
+*/
+#include "mbed.h" 
+
+enum bmp085_oss {ULTRALOW,  //samples 1 time
+                 STANDARD,  //samples twice
+                 HIGH,      //samples 4 times
+                 ULTRAHIGH};//samples 8 times
+
+             
+I2C i2c(p9, p10); // sda, scl 
+Serial pc(USBTX, USBRX); // tx, rx
+
+const int bmp085_address = 0xEE; //address of bmp085
+const int P0 = 101325; //pressure at sea level  
+
+
+void bmp085_calibration(void);
+void display_calibration(void); 
+unsigned short read_short(int,int);
+void write_char(int,int,int);
+
+long get_raw_temp(void);
+void calculations(long);
+float get_altitude(long);
+    
+short AC1, AC2, AC3, B1, B2, MB, MC, MD, OSS;
+unsigned short  AC4, AC5, AC6;
+ 
+
+
+
+
+
+int main() {
+    
+    //Initialize
+    OSS = STANDARD; //change between enums under bmp085_oss for desired Sampling resolution
+    
+    //calibrate        
+    bmp085_calibration();
+    display_calibration();    
+    
+    long raw_temp = get_raw_temp();
+    
+    calculations(raw_temp);
+          
+    //float altitude = get_altitude(pressure);
+    
+    //pc.printf("Temperature: %f\n",temperature);
+    //pc.printf("Pressure: %l\n", pressure);
+    //pc.printf("Altitude: %f\n", altitude);
+    
+      
+}
+
+long get_raw_temp(void)
+{   
+    long raw_temp; 
+    
+    //Read raw temperature value    
+    write_char(bmp085_address, 0xF4, 0x2E);
+    wait_ms(4.5);
+    raw_temp = read_short(bmp085_address, 0xF6);
+    
+    return raw_temp;
+}
+
+void calculations(long raw_temp)
+{    
+    long X1, X2, B5, temperature;
+    
+    //Start temperature calculation
+    X1 = (((long)raw_temp - (long)AC6) * (long)AC5) >> 15;
+    X2 = ((long)MC << 11) / (X1 + MD);
+    B5 = X1 + X2;
+    temperature = ((B5 + 8) >> 4);
+    
+    temperature = ((float)temperature / 10.0);
+    
+    pc.printf("Temperature: %f\n",temperature);
+  
+  
+    long raw_pressure, B6, B3, pressure, X3;
+    unsigned long B4, B7;
+    
+    //Read raw pressure value
+    write_char(bmp085_address, 0xf4, 0x34 | (OSS << 6));
+    wait_ms(5);
+    raw_pressure = read_short(bmp085_address, 0xF6) >> (8 - OSS);
+    
+    //Start Pressure calculation
+    B6 = B5 - 4000;
+    X1 = (B2 * (B6 * B6) >> 12) >> 11;
+    X2 = (AC2 * B6) >> 11;
+    X3 = X1 + X2;
+    B3 = (((AC1 * 4 + X3) << OSS + 2) / 4);
+    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)(raw_pressure - B3) * (50000 >> OSS));
+    if (B7 < 0x80000000)
+        pressure = (B7 *2) / B4;
+    else
+        pressure = (B7 / B4) * 2;
+        
+    X1 = (pressure >> 8) * (pressure >>8);
+    X1 = (X1 * 3038) >>16;
+    X2 = (-7357 * pressure) >>16;
+    pressure += (X1 + X2 + 3791)>>4;
+    
+    pc.printf("Pressure: %f\n", pressure);
+    
+}
+ 
+float get_altitude(long pressure)
+{
+    float altitude;
+    
+    altitude = (float)44330 * (1 - pow(( pressure/P0), 0.190295)); 
+    
+    pc.printf("Altitude: %f\n", altitude);
+    return altitude;   
+    
+}
+
+void bmp085_calibration(void)
+{    
+    AC1 = read_short(bmp085_address, 0xAA);
+    AC2 = read_short(bmp085_address, 0xAC);
+    AC3 = read_short(bmp085_address, 0xAE);
+    AC4 = read_short(bmp085_address, 0xB0);    
+    AC5 = read_short(bmp085_address, 0xB2);
+    AC6 = read_short(bmp085_address, 0xB4);
+    B1  = read_short(bmp085_address, 0xB6);
+    B2  = read_short(bmp085_address, 0xB8);
+    MB  = read_short(bmp085_address, 0xBA);
+    MC  = read_short(bmp085_address, 0xBC);
+    MD  = read_short(bmp085_address, 0xBE);   
+ 
+}
+
+void display_calibration(void)
+{ 
+    pc.printf("Calibration Values:\n");
+    pc.printf("AC1 = %d\n",AC1);
+    pc.printf("AC2 = %d\n",AC2);
+    pc.printf("AC3 = %d\n",AC3);
+    pc.printf("AC4 = %d\n",AC4);
+    pc.printf("AC5 = %d\n",AC5);
+    pc.printf("AC6 = %d\n",AC6);
+    pc.printf("B1 = %d\n",B1);
+    pc.printf("B2 = %d\n",B2);
+    pc.printf("MB = %d\n",MB);
+    pc.printf("MC = %d\n",MC);
+    pc.printf("MD = %d\n",MD); 
+}
+    
+unsigned short read_short(int device_address,int address){
+    unsigned short value;
+    
+    i2c.start();
+    i2c.write(device_address);
+    i2c.write(address);
+    
+    i2c.start();
+    i2c.write(device_address | 1);
+    value = i2c.read(1) << 8;
+    value |= i2c.read(0);
+    i2c.stop();
+    
+    return value;
+    
+}
+
+void write_char(int device_address, int address, int data)
+{
+    i2c.start();
+    i2c.write(device_address);
+    i2c.write(address);
+    i2c.write(data);
+    i2c.stop();
+}   
+    
+    
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