Datasheet

DS1922L/DS1922T
Temperature Logger iButton with 8KB
Data-Log Memory
16 ______________________________________________________________________________________
Memory
Figure 5 shows the DS1922L/DS1922T memory map.
Pages 0 to 15 contain 512 bytes of general-purpose
SRAM. The various registers to set up and control the
device fill pages 16 and 17, called register pages 1
and 2 (see Figure 6 for details). Pages 18 and 19 pro-
vide storage space for calibration data. They can alter-
natively be used as an extension of the general-
purpose memory. The data-log logging memory starts
at address 1000h (page 128) and extends over 256
pages. The memory pages 20 to 127 are reserved for
future extensions. The scratchpad is an additional page
that acts as a buffer when writing to the SRAM memory
or the register pages. The data memory can be written
at any time. The calibration memory holds data from the
device calibration that can be used to further improve
the accuracy of 11-bit temperature readings. See the
Software Correction Algorithm for Temperature section
for details. The last byte of the calibration memory page
stores an 8-bit CRC of the preceding 31 bytes. Page 19
is an exact copy of the data in page 18. While calibra-
tion memory can be overwritten by the user, this is not
recommended. See the
Security by Password section
for ways to protect the memory. The access type for the
register pages is register-specific and depends on
whether the device is programmed for a mission. Figure
6 shows the details. The data-log memory is read only
for the user. It is written solely under supervision of the
on-chip control logic. Due to the special behavior of the
write access logic (write scratchpad, copy scratchpad),
it is recommended to only write full pages at a time.
This also applies to the register pages and the calibra-
tion memory. See the
Address Registers and Transfer
Status section for details.
32-BYTE INTERMEDIATE STORAGE
SCRATCHPAD
ADDRESS
0000h TO 001Fh
32-BYTE GENERAL-PURPOSE SRAM
(R/W)
PAGE 0
0020h TO 01FFh GENERAL-PURPOSE SRAM (R/W) PAGES 1 TO 15
0200h TO 021Fh 32-BYTE REGISTER PAGE 1 PAGE 16
0220h TO 023Fh 32-BYTE REGISTER PAGE 2 PAGE 17
0240h TO 025Fh CALIBRATION MEMORY PAGE 1 (R/W) PAGE 18
0260h TO 027Fh CALIBRATION MEMORY PAGE 2 (R/W) PAGE 19
0280h TO 0FFFh (RESERVED FOR FUTURE EXTENSIONS) PAGES 20 TO 127
1000h TO 2FFFh DATA-LOG MEMORY (READ ONLY) PAGES 128 TO 383
Figure 5. Memory Map