DS1972 Maxim, DS1972 Datasheet - Page 22

• Manufacturer Part Number: DS1972
• Description: The DS1972 is a 1024-bit, 1-Wire® EEPROM chip organized as four memory pages of 256 bits each in a rugged iButton® package
• Manufacturer: Maxim

1024-Bit EEPROM iButton
Write to the first 8 bytes of memory page 1. Read the
entire memory.
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.
22
MASTER MODE
______________________________________________________________________________________
Rx
Rx
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
PACKAGE TYPE
Memory Function Example
F3 iButton
F5 iButton
DATA (LSB FIRST)
<2 Bytes CRC-16>
<2 Bytes CRC-16>
<1-Wire Idle High>
<144 Data Bytes>
<8 Data Bytes>
<8 Data Bytes>
(Presence)
(Presence)
(Presence)
(Presence)
(Presence)
(Reset)
(Reset)
(Reset)
(Reset)
(Reset)
CCh
CCh
AAh
CCh
AAh
CCh
0Fh
20h
00h
20h
00h
07h
55h
20h
00h
07h
F0h
00h
00h
PACKAGE CODE
IB+3NT
IB+5NT
With only a single DS1972 connected to the bus mas-
ter, the communication looks like this:
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
E/S
Wait t
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
PROGMAX
Package Information
(AUTHORIZATION CODE)
for the copy function to complete
COMMENTS
DOCUMENT NO.
21-0252
21-0266