DS1921G Maxim, DS1921G Datasheet - Page 10

• Manufacturer Part Number: DS1921G
• Description: The DS1921G Thermochron® iButton® is a rugged, self-sufficient system that measures temperature and records the result in a protected memory section
• Manufacturer: Maxim

Thermochron iButton
Figure 5. Memory Map
Figure 6. Register Pages Map
10
* The left entry in the ACCESS column is valid between missions. The right entry shows the applicable access mode while a
mission is in progress.
** While a mission is in progress, these addresses can be read. The first attempt to write to these registers (even read-only
ones), however, ends the mission and overwrites selected writable registers.
ADDRESS
______________________________________________________________________________________
020Ah
020Bh
020Ch
020Dh
020Eh
0200h
0201h
0202h
0203h
0204h
0205h
0206h
0207h
0208h
0209h
020Fh
0000h to 01FFh
0200h to 021Fh
0220h to 027Fh
0280h to 07FFh
0800h to 087Fh
0880h to 0FFFh
1000h to 17FFh
1800h to 1FFFh
ADDRESS
CENT
EOSC
BIT 7
MM
MH
MD
MS
0
0
0
0
0
EMCLR
12/24
12/24
BIT 6
Number of Minutes Between Temperature Conversions
0
0
0
0
10 Years
10 Seconds Alarm
10 Minutes Alarm
10 Seconds
10 Minutes
20 Hour
20 Hour
AM/PM
AM/PM
Alarm
BIT 5
32-BYTE INTERMEDIATE STORAGE SCRATCHPAD
Temperature High Alarm Threshold
Temperature Low Alarm Threshold
0
0
0
0
10 Date
(No function, reads 00h)
GENERAL-PURPOSE SRAM (16 PAGES)
ALARM TIMESTAMPS AND DURATIONS
TEMPERATURE HISTOGRAM MEMORY
(RESERVED FOR FUTURE EXTENSIONS)
(RESERVED FOR FUTURE EXTENSIONS)
(RESERVED FOR FUTURE EXTENSIONS)
10 Hour
10 Hour
Months
DATA-LOG MEMORY (64 PAGES)
Alarm
BIT 4
EM
10
0
0
32-BYTE REGISTER PAGE
BIT 3
RO
0
0
Single Seconds Alarm
Single Minutes Alarm
Single Hours Alarm
BIT 2
Single Seconds
Single Minutes
Single Months
TLS
Single Hours
Single Years
Single Date
Day of Week Alarm
Day of Week
BIT 1
THS
BIT 0
TAS
Sample Rate
Temperature
PAGES 192 to 255
FUNCTION
RTC Alarm
PAGES128 to 191
Registers
Registers
PAGES 68 to 127
PAGES 17 to 19
PAGES 20 to 63
PAGES 64 to 67
PAGES 0 to 15
Alarms
Control
RTC
—
PAGE 16
R/W
R/W
R/W
R/W
R/W
ACCESS*
R
R/W**
R/W**
R/W**
R/W**
R**
R**