Datasheet

DS1922L/DS1922T
Temperature Logger iButton with 8KB
Data-Log Memory
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ing in the command code, the target addresses TA1
and TA2, and all the data bytes. The DS1922L/DS1922T
transmit this CRC only if the data bytes written to the
scratchpad include scratchpad ending offset 11111b.
The data can start at any location within the scratchpad.
With the Read Scratchpad command, the CRC is gen-
erated by first clearing the CRC generator and then
shifting in the command code, the target addresses
TA1 and TA2, the E/S byte, and the scratchpad data
starting at the target address. The DS1922L/DS1922T
transmit this CRC only if the reading continues through
the end of the scratchpad, regardless of the actual
ending offset. For more information on generating CRC
values, refer to Application Note 27.
Command-Specific 1-Wire Communication Protocol—Legend
SYMBOL DESCRIPTION
RST 1-Wire reset pulse generated by master.
PD 1-Wire presence pulse generated by slave.
Select Command and data to satisfy the ROM function protocol.
WS Command “Write Scratchpad.”
RS Command “Read Scratchpad.”
CPS Command “Copy Scratchpad with Password.”
RMC Command “Read Memory with Password and CRC.”
CM Command “Clear Memory with Password.”
FC Command “Forced Conversion.”
SM Command “Start Mission with Password.”
STP Command “Stop Mission with Password.”
TA Target Address TA1, TA2.
TA-E/S Target Address TA1, TA2 with E/S byte.
<Data to EOS> Transfer of as many data bytes as are needed to reach the scratchpad offset 1Fh.
<Data to EOP> Transfer of as many data bytes as are needed to reach the end of a memory page.
<Data to EOM> Transfer of as many data bytes as are needed to reach the end of the data-log memory.
<PW/Dummy> Transfer of 8 bytes that either represent a valid password or acceptable dummy data.
<32 Bytes> Transfer of 32 bytes.
<Data> Transfer of an undetermined amount of data.
FFh Transmission of one FFh byte.
CRC-16 Transfer of an inverted CRC-16.
FF Loop Indefinite loop where the master reads FF bytes.
AA Loop Indefinite loop where the master reads AA bytes.