main.cpp

00001 #include "mbed.h"
00002 #include "SerialLCD.h"
00003  
00004 SerialLCD lcd(P1_13, P1_14);  /* Grove Serial LCD is connected to UART Tx and Rx pins*/
00005  
00006 AnalogIn thermistor(P0_11);   /* Thermistor output connected to P0_11 */
00007  
00008 int main()
00009 {
00010     char strBuffer[16];
00011     unsigned int a, beta = 3975;
00012     float temperature, resistance;
00013     
00014     lcd.begin();                 /* initialize Serial LCD communication. */ 
00015  
00016     while(1) {
00017         a = thermistor.read_u16(); /* Read analog value */
00018         
00019         /* Calculate the resistance of the thermistor from analog votage read. */
00020         resistance= (float) 10000.0 * ((65536.0 / a) - 1.0);
00021         
00022         /* Convert the resistance to temperature using Steinhart's Hart equation */
00023         temperature=(1/((log(resistance/5000.0)/beta) + (1.0/298.15)))-273.15; 
00024         
00025         sprintf(strBuffer, "Tmp %4.2f deg C", temperature); /* prepare a string buffer to print number */   
00026         lcd.setCursor(0, 0);  /* set cursor at 0th column and 0st row */
00027         lcd.print(strBuffer); /* print the string buffer */
00028       
00029         wait(0.5);
00030     }
00031 }