void ow_parasite_disable(void)
{
OW_DIR_IN();
#if (!OW_USE_INTERNAL_PULLUP)
OW_OUT_LOW();
#endif
}
uint8_t ow_reset(void)
{
uint8_t err;
OW_OUT_LOW();
OW_DIR_OUT(); // pull OW-Pin low for 480us
_delay_us(480);
ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
// set Pin as input - wait for clients to pull low
OW_DIR_IN(); // input
#if OW_USE_INTERNAL_PULLUP
OW_OUT_HIGH();
#endif
_delay_us(64); // was 66
err = OW_GET_IN(); // no presence detect
// if err!=0: nobody pulled to low, still high
}
// after a delay the clients should release the line
// and input-pin gets back to high by pull-up-resistor
_delay_us(480 - 64); // was 480-66
if ( OW_GET_IN() == 0 ) {
err = 1; // short circuit, expected low but got high
}
return err;
}
uint8_t ow_reset(void)
{
uint8_t err;
uint8_t sreg;
OW_OUT_LOW(); // disable internal pull-up (maybe on from parasite)
OW_DIR_OUT(); // pull OW-Pin low for 480us
_delay_us(480);
sreg=SREG;
cli();
// set Pin as input - wait for clients to pull low
OW_DIR_IN(); // input
_delay_us(66);
err = OW_GET_IN(); // no presence detect
// nobody pulled to low, still high
SREG=sreg; // sei()
// after a delay the clients should release the line
// and input-pin gets back to high due to pull-up-resistor
_delay_us(480-66);
if( OW_GET_IN() == 0 ) // short circuit
err = 1;
return err;
}
/*********************************
*RESET
-*********************************/
uint8_t
ow_reset(void)
{ uint8_t err;
uint8_t sreg;
OW_OUT_LOW(); // disable internal pull-up (maybe on from parasite)
OW_DIR_OUT(); // pull OW-Pin low for 480us
// delay_us(480);
usecsleep(2,240);
//timer1_Delay(480);
sreg=SREG;
/*TRY it*///
CLI();
/* set Pin as input - wait for clients to pull low*/
OW_DIR_IN(); /* input*/
// delay_us(66);
usecsleep(2,33);
//timer1_Delay(480);
err = OW_GET_IN(); /* no presence detect*/
/* nobody pulled to low, still high*/
/*TRY it*///SREG=sreg; /*
SEI();
/* after a delay the clients should release the line
and input-pin gets back to high due to pull-up-resistor*/
// delay_us(480-66);
usecsleep(2,207);
//timer1_Delay(480-66);
if( OW_GET_IN() == 0 )/* short circuit*/ err = 1;
return err;
}
/* Timing issue when using runtime-bus-selection (!OW_ONE_BUS):
The master should sample at the end of the 15-slot after initiating
the read-time-slot. The variable bus-settings need more
cycles than the constant ones so the delays had to be shortened
to achive a 15uS overall delay
Setting/clearing a bit in I/O Register needs 1 cyle in OW_ONE_BUS
but around 14 cyles in configureable bus (us-Delay is 4 cyles per uS) */
static uint8_t ow_bit_io_intern( uint8_t b, uint8_t with_parasite_enable )
{
/*ATOMIC_BLOCK(ATOMIC_RESTORESTATE) */{
#if OW_USE_INTERNAL_PULLUP
OW_OUT_LOW();
#endif
OW_DIR_OUT(); // drive bus low
_delay_us(2); // T_INT > 1usec accoding to timing-diagramm
if ( b ) {
OW_DIR_IN(); // to write "1" release bus, resistor pulls high
#if OW_USE_INTERNAL_PULLUP
OW_OUT_HIGH();
#endif
}
// "Output data from the DS18B20 is valid for 15usec after the falling
// edge that initiated the read time slot. Therefore, the master must
// release the bus and then sample the bus state within 15ussec from
// the start of the slot."
_delay_us(15-2-OW_CONF_DELAYOFFSET);
if( OW_GET_IN() == 0 ) {
b = 0; // sample at end of read-timeslot
}
_delay_us(60-15-2+OW_CONF_DELAYOFFSET);
#if OW_USE_INTERNAL_PULLUP
OW_OUT_HIGH();
#endif
OW_DIR_IN();
if ( with_parasite_enable ) {
ow_parasite_enable();
}
} /* ATOMIC_BLOCK */
_delay_us(OW_RECOVERY_TIME); // may be increased for longer wires
return b;
}
uint8_t
ow_reset(uint8_t pin)
{
uint8_t err;
err = 0;
/* Pull bus low */
OW_OUT_LOW(pin); /* disable internal pull-up (can be on from parasite) */
OW_DIR_OUTPUT(pin); /* pull OW-Pin low for 480us */
ow_delay_usec(RESET_DELAY); /* Wait for some time */
/* Release bus */
OW_DIR_INPUT(pin); /* Set pin as input - wait for clients to pull low. */
ow_delay_usec(DIR_DELAY);
/* Sample data */
err = OW_GET_INPUT(pin); /* no presence detect */
/* After a delay the clients should release the line
and input-pin gets back to high due to pull-up-resistor. */
ow_delay_usec(INPUT_DELAY);
if (OW_GET_INPUT(pin) == 0) { /* short circuit */
err = 1;
}
return err;
}
void ow_parasite_disable(void)
{
OW_OUT_LOW();
OW_DIR_IN();
}
