main.cpp

00001 /* Grove - Temprature Sensor demo v1.0
00002 *  This sensor detects the enviroment temprature,
00003 *  Uses a Arch-Pro board with Grove Base Shield
00004 *  Connect the Grove Temperature sensor to A0 and
00005 *  connect a Grove 4 digit LED display to the UART connector
00006 *  The temperature will be displayed in Celcius
00007 *  Modified by David Bottrill from the original Arduino code
00008 *  Reference: http://www.seeedstudio.com
00009 */
00010 
00011 #include "mbed.h"
00012 #include "DigitDisplay.h"
00013 
00014 DigitalOut myled(LED2);
00015 
00016 DigitDisplay display(P4_29, P4_28);
00017 AnalogIn ain(P0_23);
00018 
00019 int a;
00020 float temperature;
00021 int B=3975;                                                         //B value of the thermistor
00022 float resistance;
00023 
00024 int main()
00025 {
00026     while(1) {
00027 // multiply ain by 675 if the Grove shield is set to 5V or 1023 if set to 3.3V
00028         a=ain*675;
00029         resistance=(float)(1023-a)*10000/a;                         //get the resistance of the sensor;
00030         temperature=1/(log(resistance/10000)/B+1/298.15)-273.15;    //convert to temperature via datasheet ;
00031         myled = 1;
00032         wait(0.8);
00033         myled = 0;
00034         wait(0.8);
00035         display.write(temperature);
00036     }
00037 }
00038 
00039