Rainbow Electronics DS1972 - Manual (Page 22)

DS1972: 1024-Bit EEPROM iButton
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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".
RM Command "Read Memory".
TA Target Address TA1, TA2.
TA-E/S Target Address TA1, TA2 with E/S byte.
<8 – T2:T0 bytes> Transfer of as many bytes as needed to reach the end of the scratchpad for a given
target address.
<data to EOM> Transfer of as many data bytes as are needed to reach the end of the memory.
CRC16\ Transfer of an inverted CRC16.
FF loop Indefinite loop where the master reads FF bytes.
AA loop Indefinite loop where the master reads AA bytes.
Programming Data transfer to EEPROM; no activity on the 1-Wire bus permitted during this time.
WRITE SCRATCHPAD (CANNOT FAIL)
RST PD Select WS TA <8 – T2:T0 bytes> CRC16\ FF loop
READ SCRATCHPAD (CANNOT FAIL)
RST PD Select RS TA-E/S <8 – T2:T0 bytes> CRC16\ FF loop
COPY SCRATCHPAD (SUCCESS)
RST PD Select CPS TA-E/S Programming AA loop
COPY SCRATCHPAD (INVALID ADDRESS OR PF = 1 OR COPY PROTECTED)
RST PD Select CPS TA-E/S FF loop
READ MEMORY (SUCCESS)
RST PD Select RM TA <data to EOM> FF loop
READ MEMORY (INVALID ADDRESS)
RST PD Select RM TA FF loop