Hello,
i am trying to comunicate with DS18B20, with library from internet. But "int Temp" always is 0,0625. I am analyze 1wire by Logic analyzer and DS18B20 correct response 12bit data. Why is "Temp" always constant? Thank You.
#include <msp430g2553.h>
#include <stdint.h>
#include "DS18B20.h"
#include "delay.h"
void ow_portsetup()
{
OWPORTDIR |= OWPORTPIN;
OWPORTOUT |= OWPORTPIN;
OWPORTREN |= OWPORTPIN;
}
/***************************************************************/
float ReadDS1820(void)
{
unsigned int i;
uint16_t byte = 0;
for (i = 16; i > 0; i--)
{
byte >>= 1;
if (onewire_read_bit())
{
byte |= 0x8000;
}
}
return byte;
}
float GetData(void)
{
uint16_t temp;
onewire_reset();
onewire_write_byte(0xcc); // skip ROM command
onewire_write_byte(0x44); // convert T command
OW_HI
DELAY_MS(750); // at least 750 ms for the default 12-bit resolution
onewire_reset();
onewire_write_byte(0xcc); // skip ROM command
onewire_write_byte(0xbe); // read scratchpad command
temp = ReadDS1820();
if (temp < 0x8000)
{
return (temp * 0.0625);
}
else
{
temp = (~temp) + 1;
return (temp * 0.0625);
}
}
int onewire_reset()
{
OW_LO
DELAY_US(480); // 480us minimum
OW_RLS
DELAY_US(40); // slave waits 15-60us
if (OWPORTIN & OWPORTPIN)
return 1; // line should be pulled down by slave
DELAY_US(300); // slave TX presence pulse 60-240us
if (!(OWPORTIN & OWPORTPIN))
return 2; // line should be "released" by slave
return 0;
}
//#####################################################################
void onewire_write_bit(int bit)
{
// DELAY_US(1); // recovery, min 1us
OW_HI
if (bit)
{
OW_LO
DELAY_US(5); // max 15us
OW_RLS
// input
DELAY_US(56);
}
else
{
OW_LO
DELAY_US(60); // min 60us
OW_RLS
// input
DELAY_US(1);
}
}
//#####################################################################
int onewire_read_bit()
{
int bit = 0;
// DELAY_US(1); // recovery, min 1us
OW_LO
DELAY_US(5); // hold min 1us
OW_RLS
DELAY_US(10); // 15us window
if (OWPORTIN & OWPORTPIN)
{
bit = 1;
}
DELAY_US(46); // rest of the read slot
return bit;
}
//#####################################################################
void onewire_write_byte(uint8_t byte)
{
int i;
for (i = 0; i < 8; i++)
{
onewire_write_bit(byte & 1);
byte >>= 1;
}
}
//#####################################################################
uint8_t onewire_read_byte()
{
unsigned int i;
uint8_t byte = 0;
for (i = 0; i < 8; i++)
{
byte >>= 1;
if (onewire_read_bit())
byte |= 0x80;
}
return byte;
}
