DS1972_10 Datasheet, PDF (22/23 Pages) Maxim Integrated Products – 1024-Bit EEPROM iButton

1024-Bit EEPROM iButton
Memory Function Example
Write to the first 8 bytes of memory page 1. Read the
entire memory.
MASTER MODE
Tx
Rx
Tx
Tx
Tx
Tx
Tx
Rx
Tx
Rx
Tx
Tx
Rx
Rx
Rx
Rx
Rx
Tx
Rx
Tx
Tx
Tx
Tx
Tx
—
Rx
Tx
Rx
Tx
Tx
Tx
Tx
Rx
Tx
Rx
DATA (LSB FIRST)
(Reset)
(Presence)
CCh
0Fh
20h
00h
<8 Data Bytes>
<2 Bytes CRC-16>
(Reset)
(Presence)
CCh
AAh
20h
00h
07h
<8 Data Bytes>
<2 Bytes CRC-16>
(Reset)
(Presence)
CCh
55h
20h
00h
07h
<1-Wire Idle High>
AAh
(Reset)
(Presence)
CCh
F0h
00h
00h
<144 Data Bytes>
(Reset)
(Presence)
With only a single DS1972 connected to the bus mas-
ter, the communication looks like this:
COMMENTS
Reset pulse
Presence pulse
Issue “Skip ROM” command
Issue “Write Scratchpad” command
TA1, beginning offset = 20h
TA2, address = 0020h
Write 8 bytes of data to scratchpad
Read CRC to check for data integrity
Reset pulse
Presence pulse
Issue “Skip ROM” command
Issue “Read Scratchpad” command
Read TA1, beginning offset = 20h
Read TA2, address = 0020h
Read E/S, ending offset = 111b, AA, PF = 0
Read scratchpad data and verify
Read CRC to check for data integrity
Reset pulse
Presence pulse
Issue “Skip ROM” command
Issue “Copy Scratchpad” command
TA1
TA2
(AUTHORIZATION CODE)
E/S
Wait t_PROGMAX for the copy function to complete
Read copy status, AAh = success
Reset pulse
Presence pulse
Issue “Skip ROM” command
Issue “Read Memory” command
TA1, beginning offset = 00h
TA2, address = 0000h
Read the entire memory
Reset pulse
Presence pulse
Package Information
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in the
package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the
package regardless of RoHS status.
PACKAGE TYPE
PACKAGE CODE
DOCUMENT NO.
F3 iButton
IB+3NT
21-0252
F5 iButton
IB+5NT
21-0266
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