snooer
Joined: 22 Apr 2009
Posts: 14
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| DS18B20 and pic16f917 |
 Posted: Wed May 27, 2009 4:17 am |
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I have a problem with reading data from it. And just wondering is't code problem ore circuit. I used normal power mode for ds18b20 and allways getting 0 value from it. i used 4k7 pullup rsistor as writen and shown in datasheet.
so is't posible to use 16f917 pic with ds18b20?
my code is...
| Code: | #include <16f917.h>
#device *=16
#FUSES NOWDT //No Watch Dog Timer
#FUSES HS //High speed Osc (> 4mhz)
#FUSES NOPUT //No Power Up Timer
#FUSES NOPROTECT //Code not protected from reading
#FUSES MCLR //Master Clear pin enabled
#FUSES NOCPD //No EE protection
#FUSES BROWNOUT //Reset when brownout detected
#FUSES IESO //Internal External Switch Over mode enabled
#FUSES FCMEN //Fail-safe clock monitor enabled
#FUSES NODEBUG //No Debug mode for ICD
#use delay(clock=20000000)
#include "1wire.c"
#include "C:\Users\Mantas\Univeras\Bakalauras\PCC\flex_lcd.c"
int8 tH,tL,Conf;
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();
tH=onewire_read();
tL=onewire_read();
Conf=onewire_read();
temp3 = make16(temp2, temp1);
//result = (float) temp3 / 2.0; // 0.5 deg C resolution
result = (float) temp3 / 16.0; //0.1 deg C resolution
delay_ms(200);
return(result);
}
void main()
{
float temperature;
delay_ms(200);
lcd_init();
setup_timer_0(RTCC_INTERNAL|RTCC_DIV_1);
setup_timer_1(T1_DISABLED);
setup_timer_2(T2_DISABLED,0,1);
//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();
printf(lcd_putc "Temp= %3.1f",temperature);
}
}
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adn 1wire code..
-----------------------------
| Code: | /***********************1Wire Class***********************/
/*Description: This class handles all communication */
/* between the processor and the 1wire */
/* sensors.
/*********************************************************/
/*-------1-wire definitions-------*/
#define ONE_WIRE_PIN PIN_C6
/*******************1-wire communication functions********************/
void onewire_reset() // OK if just using a single permanently connected device
{
output_low(ONE_WIRE_PIN);
delay_us( 500 ); // pull 1-wire low for reset pulse
output_float(ONE_WIRE_PIN); // float 1-wire high
delay_us( 500 ); // wait-out remaining initialisation window.
output_float(ONE_WIRE_PIN);
}
/*********************** onewire_write() ********************************/
/*This function writes a byte to the sensor.*/
/* */
/*Parameters: byte - the byte to be written to the 1-wire */
/*Returns: */
/*********************************************************************/
void onewire_write(int data)
{
int count;
for (count=0; count<8; ++count)
{
output_low(ONE_WIRE_PIN);
delay_us( 2 ); // pull 1-wire low to initiate write time-slot.
output_bit(ONE_WIRE_PIN, shift_right(&data,1,0)); // set output bit on 1-wire
delay_us( 60 ); // wait until end of write slot.
output_float(ONE_WIRE_PIN); // set 1-wire high again,
delay_us( 2 ); // for more than 1us minimum.
}
}
/*********************** read1wire() *********************************/
/*This function reads the 8 -bit data via the 1-wire sensor. */
/* */
/*Parameters: */
/*Returns: 8-bit (1-byte) data from sensor */
/*********************************************************************/
int onewire_read()
{
int count, data;
for (count=0; count<8; ++count)
{
output_low(ONE_WIRE_PIN);
delay_us( 2 ); // pull 1-wire low to initiate read time-slot.
output_float(ONE_WIRE_PIN); // now let 1-wire float high,
delay_us( 8 ); // let device state stabilise,
shift_right(&data,1,input(ONE_WIRE_PIN)); // and load result.
delay_us( 120 ); // wait until end of read slot.
}
return( data );
}
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