вот, нашел в разделе POWERING...:
..., it is necessary to provide a strong pullup on the 1-wire bus whenever temperature conversions are taking place or data is being copied from the scratchpad to EEPROM. This can be accomplished by using a MOSFET to pull the bus directly to the rail as shown in Figure 4. The 1-wire bus must be switched to the strong pullup within 10 µs (max) after a Convert T [44h] or Copy Scratchpad [48h] command is issued, and the bus must be held high by the pullup for the duration of the conversion (tconv) or data transfer (twr = 10 ms).
и еще (CONVERT T[0x44]):
- так сделано у меняIf the DS18S20 is powered by an external supply, the master can issue read time slots after the Convert T command and the DS18S20 will respond by transmitting 0 while the temperature conversion is in progress and 1 when the conversion is done.
- а в этом случае смотрим параметры по переменному току:Temperature Conversion Time (tCONV)=750msIn parasite power mode this notification technique cannot be used since the bus is pulled high by the strong pullup during the conversion.
и тогда 1w_convert будет выглядеть как-то так:
- Код: Выделить всё • Развернуть
\ запуск преобразования,
: 1w_convert ( i-- )
1w_select
CONVERT_T
1w-c!
strong-pullup high
750 ms pause
strong-pullup low
;
and so forth.