sshahryiar
Joined: 05 May 2010
Posts: 94
Location: Dhaka, Bangladesh
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| Binary Search Algorithm and KTY-81 Thermistor |
 Posted: Thu May 08, 2014 10:27 am |
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| Code: | #include <16F88.h>
#device *= 16;
#device ADC = 10
#fuses NOMCLR, INTRC_IO, PROTECT, CPD, NOWDT
#fuses BROWNOUT, NOWRT, PUT, NOIESO, FCMEN
#use delay (internal = 4MHz)
#include <lcd420.c>
#define step 10.0
#define min -50.0
#define res 4700
#define ADC_max 1023
const unsigned long R[21] =
{
1030, 1135, 1247, 1367, 1495, 1630, 1772, 1922, 2080, 2245, 2417, 2597, 2785, 2980, 3182, 3392, 3607, 3817, 4008, 4166, 4280
};
const unsigned char symbols[16]=
{
0x07, 0x05, 0x05, 0x07, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x0E, 0x11, 0x11, 0x0A, 0x11, 0x00
};
void setup();
void lcd_symbol();
unsigned long adc_avg();
unsigned char binary_search(unsigned long long value);
void main()
{
float t = 0;
float RT = 0;
unsigned char tmp = 0;
setup();
while(TRUE)
{
RT = adc_avg();
RT = ((ADC_max / RT) - 1);
RT *= res;
tmp = binary_search(RT);
t = ((step * tmp) + min);
t += (10.0 *((RT - R[tmp]) / (R[tmp + 1] - R[tmp])));
lcd_gotoxy(1, 1);
lcd_putc("T/ C:");
lcd_gotoxy(3, 1);
lcd_putc(0);
lcd_gotoxy(7, 1);
printf(lcd_putc, "%3.2g ", t);
lcd_gotoxy(1, 2);
lcd_putc("R/k :");
lcd_gotoxy(4, 2);
lcd_putc(1);
lcd_gotoxy(7, 2);
printf(lcd_putc, "%4.2g ", RT);
delay_ms(100);
};
}
void setup()
{
disable_interrupts(global);
setup_oscillator(OSC_4MHz);
setup_WDT(WDT_off);
setup_timer_0(RTCC_INTERNAL | RTCC_8_BIT);
setup_timer_1(T1_disabled);
setup_timer_2(T2_disabled, 255, 1);
set_timer0(0);
set_timer1(0);
set_timer2(0);
setup_CCP1(CCP_off);
setup_SPI(SPI_disabled | SPI_SS_disabled);
setup_comparator(NC_NC_NC_NC);
setup_ADC(ADC_clock_internal);
setup_ADC_ports(sAN0, VSS_VDD);
set_ADC_channel(0);
lcd_init();
lcd_symbol();
}
void lcd_symbol()
{
unsigned char n = 0;
lcd_send_byte(0, 0x40);
for(n = 0; n < 16; n += 1)
{
lcd_send_byte(1, symbols[n]);
}
lcd_send_byte(0, 0x80);
}
unsigned long adc_avg()
{
unsigned char s = 32;
register unsigned long avg = 0;
while(s > 0)
{
read_ADC(ADC_start_only);
while(!ADC_done());
avg += read_ADC(ADC_read_only);
s -= 1;
}
avg >>= 5;
return avg;
}
unsigned char binary_search(unsigned long long value)
{
signed char h = 20;
signed char l = 0;
signed char m = 10;
while ((l <= h) && (l < 21) && (h > 0))
{
if(value < (R[m]))
{
h = (m - 1);
}
else
{
l = (m + 1);
}
m = (h + l);
m >>= 1;
}
return ((unsigned char)m);
}
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SShahryiar |
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