uint8_t noinline reset_onewire(uint8_t busmask)
{
/* pull bus low */
OW_CONFIG_OUTPUT(busmask);
OW_LOW(busmask);
/* wait 480us */
_delay_loop_2(OW_RESET_TIMEOUT_1);
/* release bus */
OW_CONFIG_INPUT(busmask);
/* wait 60us (maximal pause) + 30 us (half minimum pulse) */
_delay_loop_2(OW_RESET_TIMEOUT_2);
/* sample data */
uint8_t data1 = OW_GET_INPUT(busmask);
/* wait 390us */
_delay_loop_2(OW_RESET_TIMEOUT_3);
/* sample data again */
uint8_t data2 = OW_GET_INPUT(busmask);
/* if first sample is low and second sample is high, at least one device is
* attached to this bus */
return (uint8_t)(~data1 & data2 & busmask);
}
uint8_t noinline ow_read(uint8_t busmask)
{
/* a read timeslot is sent by holding the data line low for
* 1us, then wait approximately 14us, then sample data and
* wait */
/* this is also used as ow_write_1, as the only difference
* is that the return value is discarded */
OW_CONFIG_OUTPUT(busmask);
OW_LOW(busmask);
_delay_loop_2(OW_READ_TIMEOUT_1);
OW_HIGH(busmask);
OW_CONFIG_INPUT(busmask);
_delay_loop_2(OW_READ_TIMEOUT_2);
/* sample data now */
uint8_t data = (uint8_t)(OW_GET_INPUT(busmask) > 0);
/* wait for remaining slot time */
_delay_loop_2(OW_READ_TIMEOUT_3);
OW_CONFIG_OUTPUT(busmask);
return data;
}
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;
}
uint8_t
ow_io_bit(uint8_t bit, uint8_t pin)
{
OW_DIR_OUTPUT(pin); /* drive bus low */
#if 0 /* NOTE(Alexander) Too fast! */
ow_delay_usec(RECOVERY_DELAY); /* Recovery-Time wuffwuff was 1 */
#endif
if (bit) {
OW_DIR_INPUT(pin); /* if bit is 1 set bus high (by ext. pull-up) */
}
#if 0
/* wuff-wuff delay was 15uS-1 see comment above */
ow_delay_usec(WUFF_DELAY);
#endif
if (OW_GET_INPUT(pin) == 0) {
bit = 0; /* sample at end of read-timeslot */
}
ow_delay_usec(END_DELAY);
OW_DIR_INPUT(pin);
return bit;
}
unsigned
ow_input_pin_state(uint8_t pin)
{
return OW_GET_INPUT(pin);
}
