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gr1ph0n
Joined: 17 Oct 2009
Posts: 6
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| pic16f84 thermometer using DS18B20 |
 Posted: Sat Oct 17, 2009 4:35 am |
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Hello. I've built a digital thermometer with pic16f84 and DS18B20 from this site: http://www.coolcircuit.com/project/digitemp/ and it's not working very well. The sensor is showing about 72 degrees C in a room. In the original project the sensor is DS1820 but I only have DS18B20. Could someone help me modify the source codes thus showing the right temperature? I have no programming experience, that is why I am asking for your help.
The source codes:
main.c
| Code: |
#include <16F84A.h>
#use delay(clock=4000000)
#fuses NOWDT,XT, NOPUT, NOPROTECT
#include <mylcd.c>
#include <ds1820.c>
//=====================================
// main program start here
//=====================================
void main(void)
{
int buff[9], sensor, n,temp,temp_dec;
delay_ms(50);
lcd_init();
while(true)
{
sensor=0;
init_ds1820(sensor);
write_ds1820_one_byte(0xcc, sensor); // skip ROM
write_ds1820_one_byte(0x44, sensor); // perform temperature conversion
while (read_ds1820_one_byte(sensor)==0xff); // wait for conversion complete
init_ds1820(sensor);
write_ds1820_one_byte(0xcc, sensor); // skip ROM
write_ds1820_one_byte(0xbe, sensor); // read the result
for (n=0; n<9; n++) // read 9 bytes but, use only one byte
{
buff[n]=read_ds1820_one_byte(sensor); // read DS1820
}
temp=buff[0]>>1;
if ((buff[0] & 0x1)==1)
temp_dec=5;
else
temp_dec=0;
lcd_putc("\f");
printf(lcd_putc,"Temp :");
printf(lcd_putc," %u.%u'C",temp,temp_dec);
delay_ms(1000);
}
} //enf of main program
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ds1820:
| Code: |
#BYTE TRISA=0x85
#BYTE PORTA=0x5
#BYTE STATUS=0x3
#define RP0 5
#define C 0
// The following are standard 1-Wire routines.
void make_ds1820_high_pin(int sensor)
{
TRISA = 0xff;
}
void make_ds1820_low_pin(int sensor)
{
PORTA = 0x00;
TRISA = 0xff & (~(0x01 << sensor));
}
// delay routines
void delay_10us(int t)
{
#asm
BCF STATUS, RP0
DELAY_10US_X:
CLRWDT
NOP
NOP
NOP
NOP
NOP
NOP
DECFSZ t, F
GOTO DELAY_10US_X
#endasm
}
void delay_ms(long t) // delays t millisecs
{
do
{
delay_10us(100);
} while(--t);
}
void init_ds1820(int sensor)
{
make_ds1820_high_pin(sensor);
make_ds1820_low_pin(sensor);
delay_10us(50);
make_ds1820_high_pin(sensor);
delay_10us(50);
}
int read_ds1820_one_byte(int sensor)
{
int n, i_byte, temp, mask;
mask = 0xff & (~(0x01<<sensor));
for (n=0; n<8; n++)
{
PORTA=0x00;
TRISA=mask;
TRISA=0xff;
#asm
CLRWDT
NOP
NOP
#endasm
temp=PORTA;
if (temp & ~mask)
{
i_byte=(i_byte>>1) | 0x80; // least sig bit first
}
else
{
i_byte=i_byte >> 1;
}
delay_10us(6);
}
return(i_byte);
}
void write_ds1820_one_byte(int d, int sensor)
{
int n, mask;
mask = 0xff & (~(0x01<<sensor));
for(n=0; n<8; n++)
{
if (d&0x01)
{
PORTA=0;
TRISA=mask; // momentary low
TRISA=0xff;
delay_10us(6);
}
else
{
PORTA=0;
TRISA=mask;
delay_10us(6);
TRISA=0xff;
}
d=d>>1;
}
}
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I don't know if this is necessary but I'll post it anyway.
lcd.c
| Code: |
struct lcd_pin_map { // This structure is overlayed
BOOLEAN enable; // on to an I/O port to gain
BOOLEAN rs; // access to the LCD pins.
BOOLEAN rw; // The bits are allocated from
BOOLEAN unused; // low order up. ENABLE will
int data : 4; // be pin B0.
}
lcd;
#byte lcd = 6 // on to port B (at address 6)
#define set_tris_lcd(x) set_tris_b(x)
#define lcd_type 1 // 1 lines
#define lcd_line_two 0x40 // LCD RAM address for the second line
BYTE const LCD_INIT_STRING[4] = {0x20 | (lcd_type << 3),0xC,1,6};
// These bytes need to be sent to the LCD
// to start it up.
// The following are used for setting
// the I/O port direction register.
struct lcd_pin_map const LCD_WRITE = {0,0,0,0,0}; // For write mode all pins are out
struct lcd_pin_map const LCD_READ = {0,0,0,0,15}; // For read mode data pins are in
BYTE lcd_read_byte()
{
BYTE low,high;
set_tris_lcd(LCD_READ);
lcd.rw = 1;
delay_cycles(1);
lcd.enable = 1;
delay_cycles(1);
high = lcd.data;
lcd.enable = 0;
delay_cycles(1);
lcd.enable = 1;
delay_us(1);
low = lcd.data;
lcd.enable = 0;
set_tris_lcd(LCD_WRITE);
return( (high<<4) | low);
}
void lcd_send_nibble( BYTE n )
{
lcd.data = n;
delay_cycles(1);
lcd.enable = 1;
delay_us(2);
lcd.enable = 0;
}
void lcd_send_byte( BYTE address, BYTE n )
{
lcd.rs = 0;
while ( bit_test(lcd_read_byte(),7) ) ;
lcd.rs = address;
delay_cycles(1);
lcd.rw = 0;
delay_cycles(1);
lcd.enable = 0;
lcd_send_nibble(n >> 4);
lcd_send_nibble(n & 0xf);
}
void lcd_init()
{
BYTE i;
set_tris_lcd(LCD_WRITE);
lcd.rs = 0;
lcd.rw = 0;
lcd.enable = 0;
delay_ms(15);
for(i=1;i<=3;++i) {
lcd_send_nibble(3);
delay_ms(5);
}
lcd_send_nibble(2);
for(i=0;i<=3;++i)
lcd_send_byte(0,LCD_INIT_STRING[i]);
}
void lcd_gotoxy( BYTE x, BYTE y)
{
BYTE address;
if(y!=1)
address=lcd_line_two;
else
address=0;
address+=x-1;
lcd_send_byte(0,0x80|address);
}
void lcd_putc( char c)
{
switch (c) {
case '\f' : lcd_send_byte(0,1);
delay_ms(2);
break;
case '\n' : lcd_gotoxy(1,2); break;
case '\b' : lcd_send_byte(0,0x10); break;
default : lcd_send_byte(1,c); break;
}
}
char lcd_getc( BYTE x, BYTE y)
{
char value;
lcd_gotoxy(x,y);
while ( bit_test(lcd_read_byte(),7) ); // wait until busy flag is low
lcd.rs=1;
value = lcd_read_byte();
lcd.rs=0;
return(value);
}
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gr1ph0n
Joined: 17 Oct 2009
Posts: 6
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| Posted: Sun Oct 18, 2009 4:37 am |
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| Nobody can help me? |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Sun Oct 18, 2009 3:05 pm |
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| Quote: | | The sensor is showing about 72 degrees C in a room. |
What was the real temperature in your room during this test ?
(Measured by a thermometer, or by your estimate). |
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gr1ph0n
Joined: 17 Oct 2009
Posts: 6
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| Posted: Tue Oct 20, 2009 10:09 am |
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Sorry for not responding, for 2 days i had trouble with my internet connection. The real temperature was 24 degrees C. The sensor is responding, when I put it near a heat source the temperature start to grow.
Although I have no programming experience, by logic (I guess) and with examples from this site, I made a program, please don't laugh because I was desperate to made my thermometer work for my baby.
When I compile it I receive this error: "Out of ROM, A segment or the program is too large @PRINTF_L32D_74FPFPF.
And this is the program:
| Code: |
#include <16f84.h>
#use delay(clock=4000000)
#fuses NOWDT,XT, NOPUT, NOPROTECT
#include "1wire.c"
#include "mylcd.c"
float ds1820_read()
{
int8 busy=0, temp1, temp2;
signed int16 temp3;
float result;
onewire_reset();
onewire_write(0xCC);
onewire_write(0x44);
delay_ms(200);
while (busy == 0)
busy = onewire_read();
onewire_reset();
onewire_write(0xCC);
onewire_write(0xBE);
temp1 = onewire_read();
temp2 = onewire_read();
temp3 = make16(temp2, temp1);
result = (float) temp3 / 16.0; //0.1 deg C resolution
delay_ms(200);
return(result);
}
void main()
{
float temperature;
delay_ms(50);
lcd_init();
//for 10 bit resolution mod
onewire_write(0xCC);
onewire_write(0x4E);
onewire_write(125);
onewire_write(-55); //this should be done for proper working of DS18B20
onewire_write(127);
onewire_reset();
onewire_write(0xCC);
onewire_write(0x48);
delay_ms(15);
while (1)
{
temperature = ds1820_read();
lcd_putc("\f");
printf(lcd_putc,"Temp:");
printf (lcd_putc," %3.1f\n\r",temperature);
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Help me if you can, please! |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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gr1ph0n
Joined: 17 Oct 2009
Posts: 6
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| Posted: Tue Oct 20, 2009 10:51 am |
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| That is what I have used. One question. I saw that, when I used "%3.1f" the error apears, can you tell me why %3.1f was put there, please. Thank you. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Tue Oct 20, 2009 10:59 am |
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The 16F84A only has 1K rom. Floating point code uses a large amount
of ROM space. There isn't enough ROM space to do your floating point
printf statement. |
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gr1ph0n
Joined: 17 Oct 2009
Posts: 6
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| Posted: Tue Oct 20, 2009 11:02 am |
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| PCM programmer wrote: | The 16F84A only has 1K rom. Floating point code uses a large amount
of ROM space. There isn't enough ROM space to do your floating point
printf statement. |
Can I do something? I don't want something fancy, just to show the temperature.
Sorry for my noob questions and for my ignorance. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Tue Oct 20, 2009 11:14 am |
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Try displaying the result as a signed integer instead of a float.
Make the changes shown in bold below:
| Quote: | | printf (lcd_putc," %d\n\r", (signed int)temperature); |
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gr1ph0n
Joined: 17 Oct 2009
Posts: 6
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| Posted: Wed Oct 21, 2009 3:48 am |
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It worked. Thank you very much!
This is the code that worked for me with PIC16F84:
| Code: |
#include <16f84.h>
#use delay(clock=4000000)
#fuses NOWDT,XT, NOPUT, NOPROTECT
#include "1wire.c"
#include "mylcd.c"
float ds1820_read()
{
int8 busy=0, temp1, temp2;
signed int16 temp3;
float result;
onewire_reset();
onewire_write(0xCC);
onewire_write(0x44);
delay_ms(200);
while (busy == 0)
busy = onewire_read();
onewire_reset();
onewire_write(0xCC);
onewire_write(0xBE);
temp1 = onewire_read();
temp2 = onewire_read();
temp3 = make16(temp2, temp1);
result = (float) temp3 / 16.0; //0.1 deg C resolution
delay_ms(200);
return(result);
}
void main()
{
float temperature;
delay_ms(50);
lcd_init();
//for 10 bit resolution mod
onewire_write(0xCC);
onewire_write(0x4E);
onewire_write(125);
onewire_write(-55); //this should be done for proper working of DS18B20
onewire_write(127);
onewire_reset();
onewire_write(0xCC);
onewire_write(0x48);
delay_ms(15);
while (1)
{
temperature = ds1820_read();
lcd_putc("\f");
printf(lcd_putc,"Temp:");
printf (lcd_putc," %d", (signed int) temperature);
delay_ms(100);
}
}
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I want to make a statement: This is not my code! |
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