DS2422 Maxim, DS2422 Datasheet - Page 11

• Manufacturer Part Number: DS2422
• Description: The DS2422 temperature/data logger combines the core functions of a fully featured data logger in a single chip
• Manufacturer: Maxim

MEMORY
The memory map of the DS2422 is shown in Figure 7. 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 8). Pages 18 and 19 provide storage space for calibration data. They can alternatively be
used as extension of the general-purpose memory. The Trim Register Page holds registers that are used to tune
the timing of the serial data interface and to trim the on-chip temperature converter. The "datalog" logging memory
starts at address 1000h (page 128) and extends over 256 pages. The memory pages 20 to 31 and 33 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- and calibration memory can be written at any time. The access type for the
two register pages and the Trim Register Page is register-specific and depends on whether the device is pro-
grammed for a mission. Figures 8A and 8B show 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 all the
register pages and the calibration memory. See section Address Register and Transfer Status for details.
Figure 8A. DS2422 Register Pages Map
020Ch
020Dh
021Ch
021Dh
ADDR
020Ah
020Bh
020Eh
020Fh
021Ah
021Bh
021Eh
021Fh
0200h
0201h
0202h
0203h
0204h
0205h
0206h
0207h
0208h
0209h
0210h
0211h
0212h
0213h
0214h
0215h
0216h
0217h
0218h
0219h
0220h
0221h
0222h
0223h
0224h
0225h
0226h
0227h
CENT
CENT
BOR
b7
0
0
0
0
0
0
1
0
1
1
0
0
0
0
Low Byte
12/24
12/24
b6
0
0
0
0
1
0
1
1
1
0
0
10 Years
10 Years
10 Seconds
10 Seconds
10 Minutes
10 Minutes
AM/PM
AM/PM
SUTA
20h.
20h.
b5
0
0
1
0
1
0
0
10 Date
10 Date
(no function; reads 00h)
Configuration Code
WFTA
10m.
10m.
10h.
High Threshold
High Threshold
10h.
Low Threshold
Low Threshold
RO
b4
0
0
1
0
1
Center Byte
Center Byte
Center Byte
High Byte
High Byte
High Byte
High Byte
High Byte
Low Byte
Low Byte
Low Byte
Low Byte
Low Byte
EPW
MEMC
DLFS
DHF
11 of 49
LR
b3
0
0
1
0
High Byte
TLFS
Single Seconds
Single Seconds
Single Minutes
DLF
Single Minutes
Single Months
Single Months
b2
Single Hours
Single Hours
Single Years
Single Years
0
0
1
0
0
Single Date
Single Date
EDHA
ETHA
EHSS
EDL
THF
MIP
b1
0
EOSC
ETLA
EDLA
ETL
TLF
b0
0
0
Time Clock
PW. Cntrl.
D.Alm.En.
Mis. Cntrl.
Gen. Stat.
T.Alm.En.
Alm. Stat.
Function
Registers
RTC En.
Samples
Samples
Counter
Counter
Counter
Sample
Mission
Mission
Alarms
Alarms
Device
Temp.
Temp.
Stamp
Latest
Latest
Flavor
Delay
Real-
(N/A)
Time
Rate
Data
Data
Start
Access*
R/W; R
R/W; R
R/W; R
R/W; R
R/W; R
R/W; R
R/W; R
R/W; R
R/W; R
R/W; R
R; R
R; R
R; R
R; R
R; R
R; R
R; R
R; R
R; R