Exemplo n.º 1
0
static int8_t
ow_read_bit(uint8_t i)
{
    uint8_t bit;
    /* >= 1usec recovery time. */
    ow_release();
    _delay_us(1);
    /* >= 1 usec pull low to start read slot. */
    /* The read slot is time critical to a few usec, so disable interrupts. */
    cli();
    ow_low();
    _delay_us(1);
    ow_release();
    /*
      We must read the bus within at most 15 usec from pulling the bus low.
      The later we read, the more margin. But let's keep a couple usec to account
      for delays outside of _delay_us().
    */
    _delay_us(12);
    bit= ow_read();
    sei();
    if ((i % 8) == 0)
        ow_read_buf[i / 8] = 0;
    if (bit)
        ow_read_buf[i / 8] |= (1 << (i % 8));
    /* Total read slot >= 60 usec. */
    ow_delay_us(60-1-12);
    return 0;
}
Exemplo n.º 2
0
static int8_t
ow_write_bit(uint8_t bit)
{
    ow_release();
    /* Min. 1 usec recovery between slots. */
    _delay_us(1);
    if (bit)
    {
        /* Write 1: release bus within 1 usec <= T <= 15 usec. */
        /* Let's make that 2 usec just to be a bit on the safe side. */
        cli();
        ow_low();
        _delay_us(2);
        ow_release();
        sei();
        /* Total write pulse >= 60 usec. */
        ow_delay_us(60 - 2);
    }
    else
    {
        /* Write 0: pull low for 60 usec <= T <= 120 usec. */
        ow_low();
        ow_delay_us(60);
    }
    return 0;
}
Exemplo n.º 3
0
void ow_write_bit(unsigned char bit)
{
    if (!bit)
    {
    	ow_drive_low();
    	delay_microseconds(OW_C);
    	ow_release();
    	delay_microseconds(OW_D);
    }
    else
    {
    	ow_drive_low();
    	delay_microseconds(OW_A);
    	ow_release();
    	delay_microseconds(OW_B);
    }
}
Exemplo n.º 4
0
void ow_write_byte(unsigned char data)
{
  unsigned char bitcount;
  for(bitcount=8; bitcount>0; bitcount--)
  {
    if (data & 0x01)
    {
    	ow_drive_low();
    	delay_microseconds(OW_A);
    	ow_release();
    	delay_microseconds(OW_B);
    }
    else
    {
    	ow_drive_low();
    	delay_microseconds(OW_C);
    	ow_release();
    	delay_microseconds(OW_D);
    }
    data = data >> 1;
  }
}
Exemplo n.º 5
0
static int8_t
ow_convert_t(uint8_t i)
{
    if (i < 8)
        return ow_write_bit(0x44 & (1 << i));
    else
    {
        /* Temperature conversion takes max 750 msec. */
        ow_release();
        ow_delay_ms(750);
        return 0;
    }
}
Exemplo n.º 6
0
unsigned char ow_read_bit()
{
	unsigned char bit;

	ow_drive_low();
	delay_microseconds(OW_A);
	ow_release();
    delay_microseconds(OW_E);
    if (ONEWIRE_PORTIN & ONEWIRE_PINMASK){
    	bit = 1;
    }
    else
    {
    	bit = 0;
    }
    delay_microseconds(OW_F);
  	return(bit);
}
Exemplo n.º 7
0
int ow_reset()
{
  int presence;

  delay_microseconds( OW_G );
  ow_drive_low();
  delay_microseconds( OW_H );
  ow_release();
  delay_microseconds( OW_I );

  if(ONEWIRE_PORTIN & ONEWIRE_PINMASK )
  {
    presence = 0;     // bus is high, slave did not pull it down
  }
  else
  {
    presence = 1;      // bus is being pulled down, presence detected
  }

  delay_microseconds( OW_J );
  return ( presence );        // return the sampled presence pulse result
}
Exemplo n.º 8
0
static int8_t
ow_init(uint8_t i)
{
    if (i == 0)
    {
        /* Reset pulse: low for >= 480 usec. */
        ow_low();
        ow_delay_us(480);
    }
    else if (i == 1)
    {
        /* Presence detect 60 usec <= T <= 240 usec. */
        ow_release();
        ow_delay_us(60);
    }
    else
    {
        /* Total presence pulse 480 usec. */
        ow_presence= !ow_read();
        ow_delay_us(480-60);
    }
    return 0;
}
Exemplo n.º 9
0
unsigned char ow_read_byte()
{
  unsigned char data=0;
  unsigned char bitcount, bit;
  for ( bitcount=8; bitcount>0; bitcount-- )
  {
	ow_drive_low();
    delay_microseconds(OW_A);
	ow_release();
    delay_microseconds(OW_E);
    if (ONEWIRE_PORTIN & ONEWIRE_PINMASK){
    	bit = 1;
    }
    else
    {
    	bit = 0;
    }
    delay_microseconds(OW_F);
    //on 1-wire bus data is sent starting with least significant bit. We need to inert bits from the left and shift.
    data = data >> 1;
    data |= (bit << 7);
  }
  return(data);
}