Kory Hill / Mbed 2 deprecated BMP085_lib

demo program of BMP085 pressure sensor

Dependencies:   mbed

main.cpp@0:9c929de0a051, 2012-10-05 (annotated)

Committer:
newk8600
Date:
Fri Oct 05 08:03:52 2012 +0000
Revision:
0:9c929de0a051
Child:
1:2935199329b2
broken but I'll fix it...

Who changed what in which revision?

UserRevisionLine numberNew contents of line
newk8600 0:9c929de0a051 1 /*
newk8600 0:9c929de0a051 2 *
newk8600 0:9c929de0a051 3 *
newk8600 0:9c929de0a051 4 *
newk8600 0:9c929de0a051 5 * 1.8 - 3.6V (Vdd)
newk8600 0:9c929de0a051 6 * 1.62 - 3.6 (Vddio)
newk8600 0:9c929de0a051 7 *
newk8600 0:9c929de0a051 8 *
newk8600 0:9c929de0a051 9 *Altitude = 44330*(1-(p/p0)^(1/5.255))
newk8600 0:9c929de0a051 10 * set p0 to sealevel pressure
newk8600 0:9c929de0a051 11 * delta p = 1hPa = 8.43m at sea level
newk8600 0:9c929de0a051 12 *
newk8600 0:9c929de0a051 13 */
newk8600 0:9c929de0a051 14
newk8600 0:9c929de0a051 15 /*
newk8600 0:9c929de0a051 16 *Pinout:
newk8600 0:9c929de0a051 17 *pin9 = SDA
newk8600 0:9c929de0a051 18 *pin10 = SCL
newk8600 0:9c929de0a051 19 *pin11 = XCLR (digital out; active low; Resets sensor)
newk8600 0:9c929de0a051 20 *pin12 = EOC ("end of conversation"; signal when conversion finished)
newk8600 0:9c929de0a051 21 *
newk8600 0:9c929de0a051 22 *
newk8600 0:9c929de0a051 23 *
newk8600 0:9c929de0a051 24 */
newk8600 0:9c929de0a051 25 #include "mbed.h"
newk8600 0:9c929de0a051 26
newk8600 0:9c929de0a051 27 enum bmp085_oss {ULTRALOW, //samples 1 time
newk8600 0:9c929de0a051 28 STANDARD, //samples twice
newk8600 0:9c929de0a051 29 HIGH, //samples 4 times
newk8600 0:9c929de0a051 30 ULTRAHIGH};//samples 8 times
newk8600 0:9c929de0a051 31
newk8600 0:9c929de0a051 32
newk8600 0:9c929de0a051 33 I2C i2c(p9, p10); // sda, scl
newk8600 0:9c929de0a051 34 Serial pc(USBTX, USBRX); // tx, rx
newk8600 0:9c929de0a051 35
newk8600 0:9c929de0a051 36 const int bmp085_address = 0xEE; //address of bmp085
newk8600 0:9c929de0a051 37 const int P0 = 101325; //pressure at sea level
newk8600 0:9c929de0a051 38
newk8600 0:9c929de0a051 39
newk8600 0:9c929de0a051 40 void bmp085_calibration(void);
newk8600 0:9c929de0a051 41 void display_calibration(void);
newk8600 0:9c929de0a051 42 unsigned short read_short(int,int);
newk8600 0:9c929de0a051 43 void write_char(int,int,int);
newk8600 0:9c929de0a051 44
newk8600 0:9c929de0a051 45 long get_raw_temp(void);
newk8600 0:9c929de0a051 46 void calculations(long);
newk8600 0:9c929de0a051 47 float get_altitude(long);
newk8600 0:9c929de0a051 48
newk8600 0:9c929de0a051 49 short AC1, AC2, AC3, B1, B2, MB, MC, MD, OSS;
newk8600 0:9c929de0a051 50 unsigned short AC4, AC5, AC6;
newk8600 0:9c929de0a051 51
newk8600 0:9c929de0a051 52
newk8600 0:9c929de0a051 53
newk8600 0:9c929de0a051 54
newk8600 0:9c929de0a051 55
newk8600 0:9c929de0a051 56
newk8600 0:9c929de0a051 57 int main() {
newk8600 0:9c929de0a051 58
newk8600 0:9c929de0a051 59 //Initialize
newk8600 0:9c929de0a051 60 OSS = STANDARD; //change between enums under bmp085_oss for desired Sampling resolution
newk8600 0:9c929de0a051 61
newk8600 0:9c929de0a051 62 //calibrate
newk8600 0:9c929de0a051 63 bmp085_calibration();
newk8600 0:9c929de0a051 64 display_calibration();
newk8600 0:9c929de0a051 65
newk8600 0:9c929de0a051 66 long raw_temp = get_raw_temp();
newk8600 0:9c929de0a051 67
newk8600 0:9c929de0a051 68 calculations(raw_temp);
newk8600 0:9c929de0a051 69
newk8600 0:9c929de0a051 70 //float altitude = get_altitude(pressure);
newk8600 0:9c929de0a051 71
newk8600 0:9c929de0a051 72 //pc.printf("Temperature: %f\n",temperature);
newk8600 0:9c929de0a051 73 //pc.printf("Pressure: %l\n", pressure);
newk8600 0:9c929de0a051 74 //pc.printf("Altitude: %f\n", altitude);
newk8600 0:9c929de0a051 75
newk8600 0:9c929de0a051 76
newk8600 0:9c929de0a051 77 }
newk8600 0:9c929de0a051 78
newk8600 0:9c929de0a051 79 long get_raw_temp(void)
newk8600 0:9c929de0a051 80 {
newk8600 0:9c929de0a051 81 long raw_temp;
newk8600 0:9c929de0a051 82
newk8600 0:9c929de0a051 83 //Read raw temperature value
newk8600 0:9c929de0a051 84 write_char(bmp085_address, 0xF4, 0x2E);
newk8600 0:9c929de0a051 85 wait_ms(4.5);
newk8600 0:9c929de0a051 86 raw_temp = read_short(bmp085_address, 0xF6);
newk8600 0:9c929de0a051 87
newk8600 0:9c929de0a051 88 return raw_temp;
newk8600 0:9c929de0a051 89 }
newk8600 0:9c929de0a051 90
newk8600 0:9c929de0a051 91 void calculations(long raw_temp)
newk8600 0:9c929de0a051 92 {
newk8600 0:9c929de0a051 93 long X1, X2, B5, temperature;
newk8600 0:9c929de0a051 94
newk8600 0:9c929de0a051 95 //Start temperature calculation
newk8600 0:9c929de0a051 96 X1 = (((long)raw_temp - (long)AC6) * (long)AC5) >> 15;
newk8600 0:9c929de0a051 97 X2 = ((long)MC << 11) / (X1 + MD);
newk8600 0:9c929de0a051 98 B5 = X1 + X2;
newk8600 0:9c929de0a051 99 temperature = ((B5 + 8) >> 4);
newk8600 0:9c929de0a051 100
newk8600 0:9c929de0a051 101 temperature = ((float)temperature / 10.0);
newk8600 0:9c929de0a051 102
newk8600 0:9c929de0a051 103 pc.printf("Temperature: %f\n",temperature);
newk8600 0:9c929de0a051 104
newk8600 0:9c929de0a051 105
newk8600 0:9c929de0a051 106 long raw_pressure, B6, B3, pressure, X3;
newk8600 0:9c929de0a051 107 unsigned long B4, B7;
newk8600 0:9c929de0a051 108
newk8600 0:9c929de0a051 109 //Read raw pressure value
newk8600 0:9c929de0a051 110 write_char(bmp085_address, 0xf4, 0x34 | (OSS << 6));
newk8600 0:9c929de0a051 111 wait_ms(5);
newk8600 0:9c929de0a051 112 raw_pressure = read_short(bmp085_address, 0xF6) >> (8 - OSS);
newk8600 0:9c929de0a051 113
newk8600 0:9c929de0a051 114 //Start Pressure calculation
newk8600 0:9c929de0a051 115 B6 = B5 - 4000;
newk8600 0:9c929de0a051 116 X1 = (B2 * (B6 * B6) >> 12) >> 11;
newk8600 0:9c929de0a051 117 X2 = (AC2 * B6) >> 11;
newk8600 0:9c929de0a051 118 X3 = X1 + X2;
newk8600 0:9c929de0a051 119 B3 = (((AC1 * 4 + X3) << OSS + 2) / 4);
newk8600 0:9c929de0a051 120 X1 = (AC3 * B6) >> 13;
newk8600 0:9c929de0a051 121 X2 = (B1 * ((B6 * B6) >> 12)) >> 16;
newk8600 0:9c929de0a051 122 X3 = ((X1 + X2) + 2) >> 2;
newk8600 0:9c929de0a051 123 B4 = (AC4 * (unsigned long)(X3 + 32768)) >> 15;
newk8600 0:9c929de0a051 124 B7 = ((unsigned long)(raw_pressure - B3) * (50000 >> OSS));
newk8600 0:9c929de0a051 125 if (B7 < 0x80000000)
newk8600 0:9c929de0a051 126 pressure = (B7 *2) / B4;
newk8600 0:9c929de0a051 127 else
newk8600 0:9c929de0a051 128 pressure = (B7 / B4) * 2;
newk8600 0:9c929de0a051 129
newk8600 0:9c929de0a051 130 X1 = (pressure >> 8) * (pressure >>8);
newk8600 0:9c929de0a051 131 X1 = (X1 * 3038) >>16;
newk8600 0:9c929de0a051 132 X2 = (-7357 * pressure) >>16;
newk8600 0:9c929de0a051 133 pressure += (X1 + X2 + 3791)>>4;
newk8600 0:9c929de0a051 134
newk8600 0:9c929de0a051 135 pc.printf("Pressure: %f\n", pressure);
newk8600 0:9c929de0a051 136
newk8600 0:9c929de0a051 137 }
newk8600 0:9c929de0a051 138
newk8600 0:9c929de0a051 139 float get_altitude(long pressure)
newk8600 0:9c929de0a051 140 {
newk8600 0:9c929de0a051 141 float altitude;
newk8600 0:9c929de0a051 142
newk8600 0:9c929de0a051 143 altitude = (float)44330 * (1 - pow(( pressure/P0), 0.190295));
newk8600 0:9c929de0a051 144
newk8600 0:9c929de0a051 145 pc.printf("Altitude: %f\n", altitude);
newk8600 0:9c929de0a051 146 return altitude;
newk8600 0:9c929de0a051 147
newk8600 0:9c929de0a051 148 }
newk8600 0:9c929de0a051 149
newk8600 0:9c929de0a051 150 void bmp085_calibration(void)
newk8600 0:9c929de0a051 151 {
newk8600 0:9c929de0a051 152 AC1 = read_short(bmp085_address, 0xAA);
newk8600 0:9c929de0a051 153 AC2 = read_short(bmp085_address, 0xAC);
newk8600 0:9c929de0a051 154 AC3 = read_short(bmp085_address, 0xAE);
newk8600 0:9c929de0a051 155 AC4 = read_short(bmp085_address, 0xB0);
newk8600 0:9c929de0a051 156 AC5 = read_short(bmp085_address, 0xB2);
newk8600 0:9c929de0a051 157 AC6 = read_short(bmp085_address, 0xB4);
newk8600 0:9c929de0a051 158 B1 = read_short(bmp085_address, 0xB6);
newk8600 0:9c929de0a051 159 B2 = read_short(bmp085_address, 0xB8);
newk8600 0:9c929de0a051 160 MB = read_short(bmp085_address, 0xBA);
newk8600 0:9c929de0a051 161 MC = read_short(bmp085_address, 0xBC);
newk8600 0:9c929de0a051 162 MD = read_short(bmp085_address, 0xBE);
newk8600 0:9c929de0a051 163
newk8600 0:9c929de0a051 164 }
newk8600 0:9c929de0a051 165
newk8600 0:9c929de0a051 166 void display_calibration(void)
newk8600 0:9c929de0a051 167 {
newk8600 0:9c929de0a051 168 pc.printf("Calibration Values:\n");
newk8600 0:9c929de0a051 169 pc.printf("AC1 = %d\n",AC1);
newk8600 0:9c929de0a051 170 pc.printf("AC2 = %d\n",AC2);
newk8600 0:9c929de0a051 171 pc.printf("AC3 = %d\n",AC3);
newk8600 0:9c929de0a051 172 pc.printf("AC4 = %d\n",AC4);
newk8600 0:9c929de0a051 173 pc.printf("AC5 = %d\n",AC5);
newk8600 0:9c929de0a051 174 pc.printf("AC6 = %d\n",AC6);
newk8600 0:9c929de0a051 175 pc.printf("B1 = %d\n",B1);
newk8600 0:9c929de0a051 176 pc.printf("B2 = %d\n",B2);
newk8600 0:9c929de0a051 177 pc.printf("MB = %d\n",MB);
newk8600 0:9c929de0a051 178 pc.printf("MC = %d\n",MC);
newk8600 0:9c929de0a051 179 pc.printf("MD = %d\n",MD);
newk8600 0:9c929de0a051 180 }
newk8600 0:9c929de0a051 181
newk8600 0:9c929de0a051 182 unsigned short read_short(int device_address,int address){
newk8600 0:9c929de0a051 183 unsigned short value;
newk8600 0:9c929de0a051 184
newk8600 0:9c929de0a051 185 i2c.start();
newk8600 0:9c929de0a051 186 i2c.write(device_address);
newk8600 0:9c929de0a051 187 i2c.write(address);
newk8600 0:9c929de0a051 188
newk8600 0:9c929de0a051 189 i2c.start();
newk8600 0:9c929de0a051 190 i2c.write(device_address | 1);
newk8600 0:9c929de0a051 191 value = i2c.read(1) << 8;
newk8600 0:9c929de0a051 192 value |= i2c.read(0);
newk8600 0:9c929de0a051 193 i2c.stop();
newk8600 0:9c929de0a051 194
newk8600 0:9c929de0a051 195 return value;
newk8600 0:9c929de0a051 196
newk8600 0:9c929de0a051 197 }
newk8600 0:9c929de0a051 198
newk8600 0:9c929de0a051 199 void write_char(int device_address, int address, int data)
newk8600 0:9c929de0a051 200 {
newk8600 0:9c929de0a051 201 i2c.start();
newk8600 0:9c929de0a051 202 i2c.write(device_address);
newk8600 0:9c929de0a051 203 i2c.write(address);
newk8600 0:9c929de0a051 204 i2c.write(data);
newk8600 0:9c929de0a051 205 i2c.stop();
newk8600 0:9c929de0a051 206 }
newk8600 0:9c929de0a051 207
newk8600 0:9c929de0a051 208