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;
}
void onewire_init(void)
{
/* configure onewire pin as input */
OW_CONFIG_INPUT(ONEWIRE_BUSMASK);
/* release lock */
ow_global.lock = 0;
}
void
onewire_init(void)
{
/* configure onewire pin as input */
OW_CONFIG_INPUT(ONEWIRE_BUSMASK);
/* release lock */
ow_global.lock = 0;
/* initialize sensor data */
memset(ow_sensors, 0, OW_SENSORS_COUNT * sizeof(ow_sensor_t));
#ifdef ONEWIRE_NAMING_SUPPORT
/* restore sensor names */
ow_names_restore();
#endif
}
