Yihui Xiong / Mbed 2 deprecated Arch_Analog_Thermistor_Blinker

Temperature Sensing

Dependencies:   mbed

Fork of Arch_Analog_Thermistor_Blinker by Visweswara R

main.cpp@7:5c2ade6745ae, 2014-08-20 (annotated)

Committer:
yihui
Date:
Wed Aug 20 07:17:31 2014 +0000
Revision:
7:5c2ade6745ae
Parent:
6:914bd412ceda 
fix the equation and change the analog pin

Who changed what in which revision?

UserRevisionLine numberNew contents of line
viswesr 0:ed40790a022a 1 #include "mbed.h"
viswesr 0:ed40790a022a 2
yihui 7:5c2ade6745ae 3 AnalogIn thermistor(A1); /* Temperature sensor connected to Analog Grove connector */
viswesr 5:d035275d4c21 4
viswesr 5:d035275d4c21 5 DigitalOut tensplaceLED(LED4); /* This led blinks as per tens place of temperature value(in deg C) */
viswesr 5:d035275d4c21 6 DigitalOut unitsplaceLED(LED1); /* This led blinks as per units place of temperature value(in deg C) */
viswesr 0:ed40790a022a 7
viswesr 0:ed40790a022a 8 int main()
viswesr 0:ed40790a022a 9 {
viswesr 5:d035275d4c21 10 unsigned int a, beta = 3975, units, tens;
viswesr 5:d035275d4c21 11 float temperature, resistance;
viswesr 5:d035275d4c21 12
viswesr 0:ed40790a022a 13 while(1) {
viswesr 5:d035275d4c21 14 a = thermistor.read_u16(); /* Read analog value */
viswesr 5:d035275d4c21 15
viswesr 5:d035275d4c21 16 /* Calculate the resistance of the thermistor from analog votage read. */
viswesr 6:914bd412ceda 17 resistance= (float) 10000.0 * ((65536.0 / a) - 1.0);
viswesr 5:d035275d4c21 18
viswesr 5:d035275d4c21 19 /* Convert the resistance to temperature using Steinhart's Hart equation */
yihui 7:5c2ade6745ae 20 temperature=(1/((log(resistance/10000.0)/beta) + (1.0/298.15)))-273.15;
viswesr 5:d035275d4c21 21
viswesr 5:d035275d4c21 22 units = (int) temperature % 10;
viswesr 5:d035275d4c21 23 tens = (int) temperature / 10;
viswesr 5:d035275d4c21 24
viswesr 5:d035275d4c21 25
viswesr 5:d035275d4c21 26 for(int i=0; i< tens; i++)
viswesr 5:d035275d4c21 27 {
viswesr 5:d035275d4c21 28 tensplaceLED = 1;
viswesr 5:d035275d4c21 29 wait(.200);
viswesr 5:d035275d4c21 30 tensplaceLED = 0;
viswesr 5:d035275d4c21 31 wait(.200);
viswesr 4:ba523da0d68a 32 }
viswesr 5:d035275d4c21 33
viswesr 5:d035275d4c21 34 for(int i=0; i< units; i++)
viswesr 5:d035275d4c21 35 {
viswesr 5:d035275d4c21 36 unitsplaceLED = 1;
viswesr 5:d035275d4c21 37 wait(.200);
viswesr 5:d035275d4c21 38 unitsplaceLED = 0;
viswesr 5:d035275d4c21 39 wait(.200);
viswesr 5:d035275d4c21 40 }
viswesr 5:d035275d4c21 41
viswesr 5:d035275d4c21 42 wait(0.5);
viswesr 0:ed40790a022a 43 }
viswesr 0:ed40790a022a 44 }
viswesr 5:d035275d4c21 45