How Temperature Sensors Work and How to Connect Them to Microcontrollers

1#include "project.h"
2#include "math.h"
3#include "float.h"
4
5uint32 loop_counter, thermistor_R ;
6uint16 R_1_result, themistor_result ;
7int16  thermistor_mV, R_1_mV, temperature ;
8float  R_1_result_f, R_1_mV_f, thermistor_mV_f, ratio_f, voltage_f ;
9float  thermistor_RA_f, thermistor_RB_f ;
10float  current_mA_f, temperature_K_f ;
11
12int main(void)
13{
14    CyGlobalIntEnable;
15    
16    ADC_DelSig_1_Start() ;
17    AMux_1_Start() ;
18    
19    LCD_Start() ;
20    LCD_Position(0,0) ;
21    
22    DAC_Start() ;
23    
24    LCD_PrintString("Thermistor Test ") ;
25    CyDelay(1000) ;
26    
27    LCD_Position(0,0) ;
28
29    while(1)
30    {
31        P0_1_Write(1) ;       
32        CyDelay(100)  ;  
33        P0_1_Write(0) ; 
34        CyDelay(100)  ; 
35    
36        loop_counter++ ;  
37
38        AMux_1_Select(0) ;
39        ADC_DelSig_1_StartConvert() ;
40        ADC_DelSig_1_IsEndConversion(ADC_DelSig_1_WAIT_FOR_RESULT) ;
41    
42        P0_1_Write(0) ;   
43
44        R_1_result = ADC_DelSig_1_GetResult16() ;
45        R_1_result_f = (float)R_1_result ;
46
47        R_1_mV = (int16)ADC_DelSig_1_CountsTo_mVolts(R_1_result) ;
48        R_1_mV_f = (float)R_1_mV ;
49    
50        current_mA_f = R_1_mV_f / 10000. ;
51     
52        AMux_1_Select(1) ;
53        ADC_DelSig_1_StartConvert() ;
54        ADC_DelSig_1_IsEndConversion(ADC_DelSig_1_WAIT_FOR_RESULT) ;
55    
56        themistor_result = ADC_DelSig_1_GetResult16() ;
57    
58        thermistor_mV = (int16)ADC_DelSig_1_CountsTo_mVolts(themistor_result) ;
59    
60        thermistor_mV_f = (float)thermistor_mV ;  
61   
62        thermistor_RA_f = thermistor_mV_f / current_mA_f ;
63    
64        thermistor_R = Thermistor_1_GetResistance(R_1_mV, thermistor_mV) ;
65      
66        thermistor_RB_f = (float)thermistor_R ;
67 
68        temperature = Thermistor_1_GetTemperature(thermistor_R) ;
69    
70        DAC_SetValue( temperature - 2300 + 127 ) ;
71    
72        P0_0_Write(1) ;
73        LCD_IsReady() ;
74        LCD_Position(0,0) ;
75        LCD_PrintString("loop cnt:       ") ;
76        LCD_Position(0,10) ;      
77        LCD_PrintU32Number(loop_counter) ;
78        LCD_Position(1,0) ;
79
80        LCD_Position(1,0) ;
81        LCD_PrintString("         degrees ") ;
82        LCD_Position(1,0) ;
83        LCD_PrintNumber( temperature/100 ) ;   
84        LCD_Position(1,2) ;    
85        LCD_PrintString(".") ;     
86        LCD_PrintNumber( temperature%100 ) ;        
87        P0_0_Write(0) ;     
88    }
89}