Rainbow-electronics DS1920 Manual do Utilizador descarregar pdf (Página 19)

DS1920

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MEMORY FUNCTION EXAMPLE Table 3

Example: Bus Master initiates temperature conversion, then reads temperature.

MASTER MODE DATA (LSB FIRST) COMMENTS

TX Reset

Reset pulse( 480-960 µs)

RX Presence Presence pulse

TX 55H Issue "Match ROM" command

TX <64-bit ROM code> Issue address for DS1920

TX 44H Issue "Convert Temperature" command

TX <DATA LINE HIGH> Data line is held high for at least 0.5 seconds by bus

master to allow conversion to complete.

TX Reset Reset pulse

RX Presence Presence pulse

TX 55H Issue "Match ROM" command

TX <64-bit ROM code> Issue address for DS1920

TX BEH Issue "Read Scratchpad" command.

RX <9 data bytes> Read entire scratchpad plus CRC; the master now

recalculates the CRC of the eight data bytes received

from the scratchpad, compares the CRC calculated and

the CRC read. If they match, the master continues; if

not, this read operation is repeated.

TX Reset Reset pulse

RX Presence Presence pulse, done.

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Rainbow-electronics DS1920 Manual do Utilizador Página 19