DS1977
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With only a single DS1977 connected to the bus master, the communication is as follows:
Step 1 TX (Reset) Reset Pulse
RX (Presence) Presence Pulse
TX CCh Issue Skip ROM Command
TX 0Fh Issue Write Scratchpad Command
TX A0h TA1, Target Address = A0h (Start Address)
TX 00h TA2, Target Address = 00A0h
TX <10 Data Bytes> Write Data Bytes to Scratchpad
TX (Reset) Reset Pulse
RX (Presence) Presence Pulse
Step 2 TX CCh Issue Skip ROM Command
TX AAh Issue Read Scratchpad Command
RX A0h Read TA1, Target Address = A0h
RX 00h Read TA2, Target Address = 00A0h
RX 29h Read E/S-Byte
RX <10 Bytes>
Read from Scratchpad and Compare to what
was Written
TX (Reset) Reset Pulse
RX (Presence) Presence Pulse
Step 3 TX CCh Issue Skip ROM Command
TX 99h
Issue Copy Scratchpad with Password
Command
TX A0h TA1, Target Address = A0h
TX 00h TA2, Target Address = 00A0h
TX 29h E/S-Byte
TX <Full-Access Password> Transmit Full-Access Password (8 Bytes)
(—) (Activate Strong Pullup for t
) Supply Power for Programming
RX AAh
Read to Check for Programming Success;
AAh Means Success
TX (Reset) Reset Pulse
RX (Presence) Presence Pulse
Step 4 TX CCh Issue Skip ROM Command
TX 69h
Issue Read Memory with Password
Command
TX 80h TA1, Target Address = 80h
TX 00h TA2, Target Address = 0080h
TX <Read Password> Transmit Read Password (8 Bytes)
(—) (Activate Strong Pullup for t
) Supply Power for Reading
RX <64 Bytes> Read Data from Page 2
RX <2 Bytes CRC16> Read Inverted CRC16
Step 5 (—) (Activate Strong Pullup for t
) Supply Power for Reading
RX <64 Bytes> Read Data from Page 3
RX <2 Bytes CRC16> Read Inverted CRC16
TX (Reset) Reset Pulse
RX (Presence) Presence Pulse
