DS1977-F5- MAXIM [Maxim Integrated Products], DS1977-F5- Datasheet - Page 26

• Manufacturer Part Number: DS1977-F5-
• Description: Password-Protected 32KB EEPROM iButton
• Manufacturer: MAXIM [Maxim Integrated Products]

With only a single DS1977 connected to the bus master, the communication is as follows:
Step 1
Step 2
Step 3
Step 4
MASTER MODE
(—)
(—)
TX
TX
TX
TX
RX
RX
RX
RX
RX
RX
RX
RX
RX
RX
RX
TX
TX
TX
TX
TX
TX
TX
TX
TX
TX
TX
TX
TX
TX
TX
TX
TX
TX
TX
TX
TX
TX
TX
(Activate Strong Pullup for t
(Activate Strong Pullup for t
<Full-Access Password>
DATA (LSB FIRST)
<Read Password>
<Read Password>
<16 Bytes>
(Presence)
(Presence)
(Presence)
(Presence)
(Presence)
<8 Bytes>
(Reset)
(Reset)
(Reset)
(Reset)
(Reset)
CCh
CCh
CCh
CCh
CCh
C0h
AAh
C0h
C0h
AAh
C3h
C0h
AAh
C3h
C8h
0Fh
7Fh
7Fh
0Fh
7Fh
0Fh
7Fh
99h
26 of 29
PROG
PROG
)
)
Reset Pulse
Presence Pulse
Issue Skip ROM Command
Issue Write Scratchpad Command
TA1, Target Address = C0h (Password Start
Address)
TA2, Target Address = 7FC0h
Write 8-Byte Read Password to Scratchpad
Write 8-Byte Full-Access Password to
Scratchpad
Reset Pulse
Presence Pulse
Issue Skip ROM Command
Issue Read Scratchpad Command
Read TA1, Target Address = C0h
Read TA2, Target Address = 7FC0h
Read E/S-Byte
Read Both Passwords from Scratchpad and
Compare to what was Written
Reset Pulse
Presence Pulse
Issue Skip ROM Command
Issue Copy Scratchpad with Password
Command
TA1, Target Address = C0h
TA2, Target Address = 7FC0h
E/S-byte
Transmit 8 Dummy Bytes as Password,
Because Passwords are Not Yet Enabled
Supply Power for Programming
Read to Check for Programming Success;
AAh Means Success
Reset Pulse
Presence Pulse
Issue Skip ROM Command
Issue Verify Password Command
TA1, Target Address = C0h (Read Password
Address)
TA2, target address = 7FC0h
Transmit Read Password
Supply Power for Password Comparison
Check for Password Match; AAh = Match
Reset Pulse
Presence Pulse
Issue Skip ROM Command
Issue Verify Password Command
TA1, Target Address = C8h (Full-Access
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