main.cpp

00001 
00002 #include "mbed.h"
00003 
00004 I2C i2c(p28,p27);   //sda,scl
00005 Serial pc(USBTX,USBRX);  //serial usb config
00006 
00007 char a[5];
00008 
00009 int main()
00010 {
00011   int p1,p2,p3;          //to store adc high and low and PEC(packet error correction)
00012   int ch=0,temp_val;     //to store temparature value
00013   i2c.frequency(20000);  //I2C frequency 20000hz (20khz)
00014   
00015   
00016   while(1){
00017 
00018   do{                               //loop repeat if repeated start codition is not acknowledge
00019                       
00020                       do{            //loop repeat if device ram address(reg address where the Tobj value present) condition is not acknowledge
00021                       
00022                                                                  
00023                                   
00024                                   do{                       //loop repeat if device address acdition is not acknowledge
00025                                        pc.printf("add\t");   
00026                                          i2c.stop();          //stop i2c if not ack
00027                                     
00028                                     wait(0.2);
00029                                   i2c.start();                  //start I2C                   
00030                                         ch=i2c.write(0x00);     //device address of mlxIRtemprature sensorwith write condition
00031                                       } while(ch==0);          //wait for ack
00032                                   pc.printf("ACK1\t");           
00033                                   
00034                                   ch=i2c.write(0x07);          //device ram address where Tobj value is present
00035                        } while(ch==0);                          //wait for ack
00036                       pc.printf("ACK2\t");
00037                       
00038                       
00039                      
00040                          i2c.start();                         //repeat start
00041                          ch=i2c.write(0x01);                  //device address with read condition   
00042         }while(ch==0);                                          //wait for ack
00043          pc.printf("ACK3\t");
00044          p1=i2c.read(1);                            //Tobj low byte
00045         p2=i2c.read(1);                               //Tobj heigh byte
00046         p3=i2c.read(0);                                //PEC
00047         i2c.stop();                                 //stop condition
00048      
00049                                                             //degree centigrate conversion
00050      temp_val=((((p2&0x007f)<<8)+p1)*0.02)-0.01;
00051      temp_val=temp_val-273;                    
00052      
00053   
00054  
00055    wait(1.0); 
00056 
00057   
00058    pc.printf("rx val1 is %d\n",p1);
00059   pc.printf("rx val2 is %d\n",p2);
00060    pc.printf("rx val3 is %d\n",p3);
00061   pc.printf("temp val is %d\n",temp_val); 
00062 
00063   
00064   wait(2.0);
00065    
00066 
00067    
00068   } 
00069   
00070  
00071   
00072   return 0;
00073 }