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;
}
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;
}
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);
}
}
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;
}
}
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;
}
}
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);
}
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
}
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;
}
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);
}
