DS1921 datasheet(5/44 Pages) DALLAS

5 / 44 page

DS1921H/Z

5 of 44

1-Wire CRC GENERATOR Figure 4

Polynomial = X

8 + X5 + X4 + 1

STAGE

INPUT DATA

MEMORY

The memory map of the DS1921H/Z is shown in Figure 5. The 4096-bit general-purpose SRAM make up

pages 0 through 15. The timekeeping, control, and counter registers fill page 16, called Register Page (see

Figure 6). Pages 17 to 19 are assigned to storing the alarm time stamps and durations. The temperature

histogram bins begin at page 64 and use up to four pages. The temperature logging memory covers pages

128 to 191. Memory pages 20 to 63, 68 to 127, and 192 to 255 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 memory pages 17 and higher are read-only for the user. They are written to or erased solely

under supervision of the on-chip control logic.

DS1921H/Z MEMORY MAP Figure 5

32-Byte Intermediate Storage Scratchpad

ADDRESS

0000h to

01FFh

General-Purpose SRAM (16 Pages)

Pages 0 to 15

0200h to

021Fh

32-Byte Register Page

Page 16

0220h to

027Fh

Alarm Time Stamps and Durations

Pages 17 to 19

0280h to

07FFh

(Reserved for Future Extensions)

Pages 20 to 63

0800h to

087Fh

Temperature Histogram Memory

Pages 64 to 67

0880h to

0FFFh

(Reserved for Future Extensions)

Pages 68 to 127

1000h to

17FFh

Datalog Memory (64 Pages)

Pages 128 to 191

1800h to

1FFFh

(Reserved for Future Extensions)

Pages 192 to 255

DS1921 Datasheet(PDF) 5 Page - Dallas Semiconductor

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