
DS1922L/DS1922T
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MEMORY
The memory map of the DS1922L/T is shown in Figure 5. The 512 bytes general-purpose SRAM are located in
pages 0 through 15. The various registers to set-up and control the device fill page 16 and 17, called register pages
1 and 2 (details in Figure 6). Pages 18 and 19 provide storage space for calibration data. They can alternatively be
used as extension of the general-purpose memory. The "datalog" 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 page. 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
preceeding 31 bytes. Page 19 is an exact copy of the data in page 18. While the calibration memory can be
overwritten by the user, this is not recommended. See section
Security by Password
for ways to protect the
memory. The access type for the register pages is register-specific and depends on whether the device is pro-
grammed for a mission. Figure 6 shows the details. The datalog 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 calibration memory. See the
Address Register and Transfer Status
section for details.
Figure 5. DS1922L/T Memory Map
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
Datalog Memory (Read-Only)
Pages 128
to 383