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;
}
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;
}
/* 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;
}
void ow_write_bit(uint8_t bit)
{
cli();
if (bit)
{
// Write '1' bit
OW_DIR_OUT(); // drive bus low
_delay_us(6);
OW_DIR_IN();
_delay_us(64); // Complete the time slot and 10us recovery
}
else
{
// Write '0' bit
OW_DIR_OUT(); // drive bus low
_delay_us(60);
OW_DIR_IN();
_delay_us(10);
}
sei();
}
/* 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) */
uint8_t ow_bit_io1( uint8_t b )
{
OW_DIR_OUT_LOW(); // drive bus low
ow_delay_us(1); // Recovery-Time 1us
if ( b ) {
OW_DIR_OUT_HIGH();
}else{
OW_DIR_OUT_LOW();
}
ow_delay_us(38);
OW_DIR_IN();
ow_delay_us(2); // Recovery-Time 1us
// wuffwuff delay was 15uS-1 see comment above
OW_DIR_OUT_LOW(); // drive bus low
ow_delay_us(1); // Recovery-Time 1us
OW_DIR_IN();
ow_delay_us(7);
b=ow_input_pin_state();
ow_delay_us(38);
return b;
}
/* 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) */
uint8_t ow_bit_io( uint8_t b )
{
uint8_t sreg;
sreg=SREG;
cli();
OW_DIR_OUT(); // drive bus low
delay_us(1); // Recovery-Time wuffwuff was 1
if ( b ) OW_DIR_IN(); // if bit is 1 set bus high (by ext. pull-up)
// wuffwuff delay was 15uS-1 see comment above
delay_us(15-1-OW_CONF_DELAYOFFSET);
if( OW_GET_IN() == 0 ) b = 0; // sample at end of read-timeslot
delay_us(60-15);
OW_DIR_IN();
SREG=sreg; // sei();
return b;
}
uint8_t ow_read_bit()
{
cli();
int result;
OW_DIR_OUT(); // drive bus low
_delay_us(6);
OW_DIR_IN();
_delay_us(6); //Recommended values say 9
if( OW_GET_IN() == 0 )
result = 0;
else
result=1; // sample at end of read-timeslot (Reading only possible with high bit)
_delay_us(58); // Complete the time slot and 10us recovery
sei();
return result;
}
// see http://www.maxim-ic.com/app-notes/index.mvp/id/162
uint8_t ow_reset(void)
{
uint8_t err;
OW_DIR_OUT_LOW(); // pull OW-Pin low for 480us
ow_delay_us(233); // min 480us in total
ow_delay_us(233);
// set Pin as input - wait for clients to pull low
OW_DIR_IN(); // input and pull up
ow_delay_us(53); // 60 us
err = ow_input_pin_state(); // devices should now pull low
// nobody pulled to low, still high-> error
// after a delay the clients should release the line
// and input-pin gets back to high due to pull-up-resistor
ow_delay_us(233); // max 240us in total
if (err==1){
return(1); // no presence puls
}
if( ow_input_pin_state() == 0 ) // short circuit
return(1);
return(0);
}
void ow_parasite_disable(void)
{
OW_OUT_LOW();
OW_DIR_IN();
}
void ow_parasite_disable(void) {
OW_DIR_IN();
#if (!OW_USE_INTERNAL_PULLUP)
OW_OUT_LOW();
#endif
}
