main.cpp

00001 #include "mbed.h"
00002 
00003 AnalogIn thermistor(P0_11);   /* Thermistor output connected to P0_11 */
00004 
00005 DigitalOut tensplaceLED(LED4);  /* This led blinks as per tens place of temperature value(in deg C) */
00006 DigitalOut unitsplaceLED(LED1); /* This led blinks as per units place of temperature value(in deg C) */
00007 
00008 int main()
00009 {
00010     unsigned int a, beta = 3975, units, tens;
00011     float temperature, resistance;
00012 
00013     while(1) {
00014         a = thermistor.read_u16(); /* Read analog value */
00015         
00016         /* Calculate the resistance of the thermistor from analog votage read. */
00017         resistance= (float) 10000.0 * ((65536.0 / a) - 1.0);
00018         
00019         /* Convert the resistance to temperature using Steinhart's Hart equation */
00020         temperature=(1/((log(resistance/5000.0)/beta) + (1.0/298.15)))-273.15; 
00021         
00022         units = (int) temperature % 10;
00023         tens  = (int) temperature / 10;
00024         
00025         
00026         for(int i=0; i< tens; i++)
00027         {
00028              tensplaceLED = 1;
00029              wait(.200);
00030              tensplaceLED = 0;
00031              wait(.200);
00032         }
00033         
00034         for(int i=0; i< units; i++)
00035         {
00036              unitsplaceLED = 1;
00037              wait(.200);
00038              unitsplaceLED = 0;
00039              wait(.200);
00040         }
00041       
00042         wait(0.5);
00043     }
00044 }
00045