mike egan / bmp085

I2C interface of Bosch BMP085 pressure/temperature sensor.

bmp085.cpp@3:9c82e6a0172a, 2013-04-14 (annotated)

Committer:
davernm
Date:
Sun Apr 14 10:39:11 2013 +0000
Revision:
3:9c82e6a0172a
Parent:
2:4ebe4d41b588 
1

Who changed what in which revision?

UserRevisionLine numberNew contents of line
davernm 2:4ebe4d41b588 1 /*This code was written as an example program for students advancing from C programming to C++.
davernm 2:4ebe4d41b588 2 //
davernm 2:4ebe4d41b588 3 //
davernm 2:4ebe4d41b588 4
davernm 2:4ebe4d41b588 5
davernm 2:4ebe4d41b588 6
davernm 2:4ebe4d41b588 7 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
davernm 2:4ebe4d41b588 8 * BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
davernm 2:4ebe4d41b588 9 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
davernm 2:4ebe4d41b588 10 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
davernm 2:4ebe4d41b588 11 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
davernm 2:4ebe4d41b588 12 *
davernm 2:4ebe4d41b588 13
davernm 2:4ebe4d41b588 14
davernm 2:4ebe4d41b588 15 Test code:
davernm 0:de9de5beb7af 16 //
davernm 0:de9de5beb7af 17 //
davernm 0:de9de5beb7af 18 //
davernm 0:de9de5beb7af 19 //
davernm 0:de9de5beb7af 20 //this program uses a ticker to read the BMP085 every 5 seconds and updates the lcd with
davernm 0:de9de5beb7af 21 //the pressure and temperature reading
davernm 0:de9de5beb7af 22
davernm 0:de9de5beb7af 23 #include "mbed.h"
davernm 0:de9de5beb7af 24 #include "TextLCD.h"
davernm 0:de9de5beb7af 25 #include "bmp085.h"
davernm 0:de9de5beb7af 26
davernm 0:de9de5beb7af 27
davernm 0:de9de5beb7af 28 void doConv(void);
davernm 0:de9de5beb7af 29 void dispVals(long T,long P);
davernm 0:de9de5beb7af 30
davernm 0:de9de5beb7af 31 //Three different constructors:
davernm 0:de9de5beb7af 32
davernm 0:de9de5beb7af 33 BMP085 X(p28,p27,p5,3);//create an instance,using an EOC pin and oss set to 3
davernm 0:de9de5beb7af 34 //BMP085 X(p28,p27,3);//create an instance without an EOC pin, oss 3
davernm 0:de9de5beb7af 35 //BMP085 X(p28,p27);//create an instance, no EOC, oss will default to 0
davernm 0:de9de5beb7af 36 TextLCD lcd(p7, p6, p8, p9, p10, p11);
davernm 0:de9de5beb7af 37
davernm 0:de9de5beb7af 38 Ticker myT;
davernm 0:de9de5beb7af 39
davernm 0:de9de5beb7af 40 int main() {
davernm 0:de9de5beb7af 41
davernm 0:de9de5beb7af 42 myT.attach(&doConv,5); //every 5 seconds
davernm 0:de9de5beb7af 43 X.readCal(); //read calibration data
davernm 0:de9de5beb7af 44 doConv(); //call once
davernm 0:de9de5beb7af 45 while(1)
davernm 0:de9de5beb7af 46 {
davernm 0:de9de5beb7af 47 //do something
davernm 0:de9de5beb7af 48 }
davernm 0:de9de5beb7af 49
davernm 0:de9de5beb7af 50
davernm 0:de9de5beb7af 51 }
davernm 0:de9de5beb7af 52
davernm 0:de9de5beb7af 53
davernm 0:de9de5beb7af 54 void dispVals(long T,long P)//display data on the lcd
davernm 0:de9de5beb7af 55 {
davernm 0:de9de5beb7af 56 lcd.locate(0,0); //lcd line 1
davernm 0:de9de5beb7af 57
davernm 0:de9de5beb7af 58 char buf[20],*P1="Temp:",*P2="Press:";
davernm 0:de9de5beb7af 59 lcd.printf(P2);
davernm 0:de9de5beb7af 60 lcd.locate(strlen(P2),0);
davernm 0:de9de5beb7af 61 float p=(float)P;
davernm 0:de9de5beb7af 62 p/=100;//convert to milli bar
davernm 0:de9de5beb7af 63 sprintf(buf,"%.2f",p);
davernm 0:de9de5beb7af 64 lcd.printf("%s",buf);
davernm 0:de9de5beb7af 65
davernm 0:de9de5beb7af 66 lcd.locate(0,1); // lcd line 2
davernm 0:de9de5beb7af 67 lcd.printf(P1);
davernm 0:de9de5beb7af 68 float t=(float)T;
davernm 0:de9de5beb7af 69 t/=10;//convert to deg C
davernm 0:de9de5beb7af 70 sprintf(buf,"%.2f",t);
davernm 0:de9de5beb7af 71 lcd.locate(strlen(P1),1);
davernm 0:de9de5beb7af 72 lcd.printf("%s",buf);
davernm 0:de9de5beb7af 73
davernm 0:de9de5beb7af 74
davernm 0:de9de5beb7af 75 }
davernm 0:de9de5beb7af 76 void doConv(void)
davernm 0:de9de5beb7af 77 {
davernm 0:de9de5beb7af 78 long UT,UP,T,P;
davernm 0:de9de5beb7af 79
davernm 0:de9de5beb7af 80
davernm 0:de9de5beb7af 81 UT=X.readUT(); //read uncompensated temperature
davernm 0:de9de5beb7af 82 UP= X.readUP(); //read uncompensated pressure
davernm 0:de9de5beb7af 83 X.calVals(UT,UP,&T,&P); //calculate temperature and pressure
davernm 0:de9de5beb7af 84 dispVals(T,P); //dsiplay resuls on lcd
davernm 0:de9de5beb7af 85 }
davernm 0:de9de5beb7af 86
davernm 0:de9de5beb7af 87 */
davernm 0:de9de5beb7af 88 #include "mbed.h"
davernm 0:de9de5beb7af 89 #include "bmp085.h"
davernm 0:de9de5beb7af 90
davernm 2:4ebe4d41b588 91 BMP085:: BMP085(PinName sda,PinName scl,int Oss):i2c(sda,scl){
davernm 0:de9de5beb7af 92 //this constructor does not use an end of conversion pin
davernm 0:de9de5beb7af 93 i2c.frequency(50000);
davernm 0:de9de5beb7af 94 flag=false;
davernm 0:de9de5beb7af 95 oss=Oss;
davernm 0:de9de5beb7af 96 }
davernm 2:4ebe4d41b588 97 BMP085::BMP085(PinName sda,PinName scl):i2c(sda,scl){
davernm 0:de9de5beb7af 98 //this version has no end of conversion, and has the oversampling
davernm 0:de9de5beb7af 99 //default to 0.
davernm 0:de9de5beb7af 100 i2c.frequency(50000);
davernm 0:de9de5beb7af 101 flag=false;
davernm 0:de9de5beb7af 102 oss=0;//default to 0
davernm 0:de9de5beb7af 103
davernm 0:de9de5beb7af 104 }
davernm 2:4ebe4d41b588 105 BMP085::BMP085(PinName sda,PinName scl, PinName EOC,int Oss) : i2c(sda,scl) {
davernm 0:de9de5beb7af 106 //end of conversion pin is used as well as oss being set
davernm 0:de9de5beb7af 107 //
davernm 0:de9de5beb7af 108 EOCptr = new DigitalIn(EOC);
davernm 0:de9de5beb7af 109 i2c.frequency(50000);
davernm 0:de9de5beb7af 110 flag=true; //eoc pin is present
davernm 0:de9de5beb7af 111 oss=Oss;
davernm 0:de9de5beb7af 112
davernm 0:de9de5beb7af 113 }
davernm 0:de9de5beb7af 114
davernm 0:de9de5beb7af 115
davernm 0:de9de5beb7af 116
davernm 0:de9de5beb7af 117 void BMP085::calVals(long UT,long UP, long *Temp,long *Pre)//see data sheet for calculations
davernm 0:de9de5beb7af 118 {
davernm 0:de9de5beb7af 119
davernm 0:de9de5beb7af 120 long X1,X2,X3,B6,B3,B7,p,B5,T;
davernm 0:de9de5beb7af 121 unsigned long B4;
davernm 0:de9de5beb7af 122
davernm 0:de9de5beb7af 123 X1=((UT-AC6)*AC5)>>15;
davernm 0:de9de5beb7af 124 X2=(MC<<11)/(X1+MD);
davernm 0:de9de5beb7af 125 B5=X1+X2;
davernm 0:de9de5beb7af 126 T=(B5+8)>>4;
davernm 0:de9de5beb7af 127
davernm 0:de9de5beb7af 128 *Temp=T;
davernm 0:de9de5beb7af 129 B6=B5-4000;
davernm 0:de9de5beb7af 130 X1=(B6*B6)/4096;
davernm 0:de9de5beb7af 131 X1*=B2;
davernm 0:de9de5beb7af 132 X1>>=11;
davernm 0:de9de5beb7af 133 X2=(AC2*B6)/2048;
davernm 0:de9de5beb7af 134 X3=X1+X2;
davernm 0:de9de5beb7af 135 B3=(((AC1*4+X3)<<oss)+2)/4;
davernm 0:de9de5beb7af 136 X1=(AC3*B6)>>13;
davernm 0:de9de5beb7af 137 X2=(B6*B6)>>12;
davernm 0:de9de5beb7af 138 X2*=B1;
davernm 0:de9de5beb7af 139 X2>>=16;
davernm 0:de9de5beb7af 140 X3=((X1+X2)+2)>>2;
davernm 0:de9de5beb7af 141 B4=(AC4*(unsigned long)(X3+32768))/32768;
davernm 0:de9de5beb7af 142 B7=((unsigned long)(UP-B3)*(50000>>oss));
davernm 0:de9de5beb7af 143
davernm 0:de9de5beb7af 144 if (B7<0x80000000) p=(B7*2)/B4;
davernm 0:de9de5beb7af 145
davernm 0:de9de5beb7af 146 else p=(B7/B4)*2;
davernm 0:de9de5beb7af 147 X1=(p>>8)*(p>>8);
davernm 0:de9de5beb7af 148 X1=(X1*3038)>>16;
davernm 0:de9de5beb7af 149 X2=(-7357*p)>>16;
davernm 0:de9de5beb7af 150 p+=(X1+X2+3791)>>4;
davernm 0:de9de5beb7af 151 *Pre=p;
davernm 1:30d98c558b29 152
davernm 0:de9de5beb7af 153
davernm 0:de9de5beb7af 154
davernm 0:de9de5beb7af 155 }
davernm 0:de9de5beb7af 156
davernm 0:de9de5beb7af 157 long BMP085::readUT(void) //uncompensated temperature
davernm 0:de9de5beb7af 158 {
davernm 0:de9de5beb7af 159 float delVals[]={4.5,7.5,13.5,25.5}; //data sheet values
davernm 0:de9de5beb7af 160 char wReg[2]; // write 0x2e into reg 0xf4
davernm 0:de9de5beb7af 161 wReg[0] = 0xF4;
davernm 0:de9de5beb7af 162 wReg[1] = 0x2E;
davernm 0:de9de5beb7af 163 i2c.write(0xee, wReg, 2);
davernm 0:de9de5beb7af 164 if (!flag)wait_ms(delVals[oss]);
davernm 0:de9de5beb7af 165 //use EOC
davernm 0:de9de5beb7af 166 else while (EOCptr->read()==0); //wait for 1
davernm 0:de9de5beb7af 167 // uncompensated temperature
davernm 0:de9de5beb7af 168 char cmd = 0xF6;// read reg 0xf6
davernm 0:de9de5beb7af 169 i2c.write(0xee, &cmd, 1);
davernm 0:de9de5beb7af 170
davernm 0:de9de5beb7af 171 char Arr[2];
davernm 0:de9de5beb7af 172 i2c.read(0xef,Arr,2);
davernm 0:de9de5beb7af 173 long UT=(Arr[0]<<8)|Arr[1];
davernm 0:de9de5beb7af 174 return UT;
davernm 0:de9de5beb7af 175 }
davernm 0:de9de5beb7af 176
davernm 0:de9de5beb7af 177
davernm 0:de9de5beb7af 178
davernm 0:de9de5beb7af 179 long BMP085::readUP(void)//uncompensated pressure
davernm 0:de9de5beb7af 180 {
davernm 0:de9de5beb7af 181 float delVals[]={4.5,7.5,13.5,25.5}; //data sheet values
davernm 0:de9de5beb7af 182 char wReg[2]; // write 0x34 into reg 0xf4
davernm 0:de9de5beb7af 183 wReg[0] = 0xF4;
davernm 0:de9de5beb7af 184 wReg[1] = 0x34+(oss<<6);
davernm 0:de9de5beb7af 185 i2c.write(0xee, wReg, 2);
davernm 0:de9de5beb7af 186 if (!flag)wait_ms(delVals[oss]);
davernm 0:de9de5beb7af 187 else while (EOCptr->read()==0);
davernm 0:de9de5beb7af 188 char cmd=0xf6;
davernm 0:de9de5beb7af 189 i2c.write(0xee,&cmd,1);
davernm 0:de9de5beb7af 190 char Arr[3];
davernm 0:de9de5beb7af 191 i2c.read(0xef,Arr,3); //3 byte data
davernm 0:de9de5beb7af 192 long UP=((Arr[0]<<16)|(Arr[1]<<8)|Arr[2])>>(8-oss);
davernm 1:30d98c558b29 193
davernm 0:de9de5beb7af 194
davernm 0:de9de5beb7af 195 return UP;
davernm 0:de9de5beb7af 196 }
davernm 0:de9de5beb7af 197
davernm 0:de9de5beb7af 198 void BMP085::readCal(void)//read the onboard calibration data
davernm 0:de9de5beb7af 199 {
davernm 0:de9de5beb7af 200 int i;
davernm 0:de9de5beb7af 201 char addr=0xaa;
davernm 0:de9de5beb7af 202 char dumArr[1];
davernm 0:de9de5beb7af 203
davernm 0:de9de5beb7af 204 for (i=0;i<22;i++)
davernm 0:de9de5beb7af 205 {
davernm 0:de9de5beb7af 206 i2c.write(0xee,&addr,1);
davernm 0:de9de5beb7af 207 i2c.read(0xef,dumArr,1);
davernm 0:de9de5beb7af 208 Vals[i]=dumArr[0];
davernm 0:de9de5beb7af 209 addr++;
davernm 0:de9de5beb7af 210 }
davernm 0:de9de5beb7af 211 AC1=(Vals[0]<<8)|Vals[1];
davernm 0:de9de5beb7af 212 AC2=(Vals[2]<<8)|Vals[3];
davernm 0:de9de5beb7af 213 AC3=(Vals[4]<<8)|Vals[5];
davernm 0:de9de5beb7af 214 AC4=(Vals[6]<<8)|Vals[7];
davernm 0:de9de5beb7af 215 AC5=(Vals[8]<<8)|Vals[9];
davernm 0:de9de5beb7af 216 AC6=(Vals[10]<<8)|Vals[11];
davernm 0:de9de5beb7af 217 B1=(Vals[12]<<8)|Vals[13];
davernm 0:de9de5beb7af 218 B2=(Vals[14]<<8)|Vals[15];
davernm 0:de9de5beb7af 219 MB=(Vals[16]<<8)|Vals[17];
davernm 0:de9de5beb7af 220 MC=(Vals[18]<<8)|Vals[19];
davernm 1:30d98c558b29 221 MD=(Vals[20]<<8)|Vals[21];
davernm 0:de9de5beb7af 222
davernm 0:de9de5beb7af 223 }