DS1922T-F5# Maxim Integrated Products, DS1922T-F5# Datasheet - Page 26

• Manufacturer Part Number: DS1922T-F5#
• Description: IBUTTON TEMP LOGGER
• Manufacturer: Maxim Integrated Products
• Series: iButton®r

Specifications of DS1922T-F5#

• Rohs Information: IButton RoHS Compliance Plan
• Memory Size: 512B
• Memory Type: NVSRAM (Non-Volatile SRAM)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Temperature Logger iButton with 8KB
Data-Log Memory
Before enabling password checking, passwords for
read-only access as well as for full access
(read/write/control) must be written to the password
registers. Setting up a password or enabling/dis-
abling the password checking is done in the same
way as writing data to a memory location; only the
address is different. Since they are located in the
same memory page, both passwords can be rede-
fined at the same time.
The Read Access Password must be transmitted exact-
ly in the sequence RP0, RP1…RP62, RP63. This pass-
word only applies to the Read Memory with CRC
function. The DS1922L/DS1922T deliver the requested
data only if the password transmitted by the master was
correct or if password checking is not enabled.
Note: There is only write access to this register. Attempting to read the password reports all zeros. The password cannot be
changed while a mission is in progress.
Note: There is only write access to this register. Attempting to read the password reports all zeros. The password cannot be
changed while a mission is in progress.
26
ADDRESS
ADDRESS
0228h
0229h
022Eh
022Fh
0230h
0231h
0236h
0237h
______________________________________________________________________________________
…
…
BIT 7
RP15
RP55
RP63
BIT 7
FP15
FP55
FP63
RP7
FP7
BIT 6
RP14
RP54
RP62
BIT 6
FP14
FP54
FP62
RP6
FP6
RP13
RP53
RP61
BIT 5
FP13
FP53
FP61
BIT 5
RP5
FP5
BIT 4
RP12
RP52
RP60
BIT 4
FP12
FP52
FP60
RP4
FP4
The full-access password must be transmitted exactly
in the sequence FP0, FP1…FP62, FP63. It affects the
functions Read Memory with CRC, Copy Scratchpad,
Clear Memory, Start Mission, and Stop Mission. The
DS1922L/DS1922T execute the command only if the
password transmitted by the master was correct or if
password checking is not enabled.
Due to the special behavior of the write-access logic,
the Password Control register and both passwords
must be written at the same time. When setting up new
passwords, always verify (read back) the scratchpad
before sending the Copy Scratchpad command. After a
new password is successfully copied from the scratch-
pad to its memory location, erase the scratchpad by fill-
ing it with new data (Write Scratchpad command).
Otherwise, a copy of the passwords remains in the
scratchpad for public read access.
…
…
Read Access Password Register Bitmap
Full Access Password Register Bitmap
BIT 3
RP11
RP51
RP59
BIT 3
FP11
FP51
FP59
RP3
FP3
RP10
RP50
RP58
BIT 2
BIT 2
FP10
FP50
FP58
RP2
FP2
BIT 1
RP49
RP57
BIT 1
FP49
FP57
RP1
RP9
FP1
FP9
BIT 0
RP48
RP56
BIT 0
FP48
FP56
RP0
RP8
FP0
FP8