DS2422 Maxim, DS2422 Datasheet - Page 12

• 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

Figure 8B. DS2422 Trim Register Page Map
Note: The first entry in column ACCESS TYPE is valid between missions. The second entry shows the applicable
access type while a mission is in progress.
TIMEKEEPING AND CALENDAR
The RTC and calendar information is accessed by reading/writing the appropriate bytes in the register page,
address 200h to 205h. For readings to be valid, all RTC registers must be read sequentially starting at address
0200h. Some of the RTC bits are set to 0. These bits always read 0 regardless of how they are written. The
number representation of the RTC registers is BCD format (binary-coded decimal).
Real-Time Clock Register Bitmap
The RTC of the DS2422 can run in either 12-hour or 24-hour mode. Bit 6 of the Hours Register (address 202h) is
defined as the 12- or 24-hour mode select bit. When high, the 12-hour mode is selected. In the 12-hour mode, bit 5
is the AM/PM bit with logic 1 being PM. In the 24-hour mode, bit 5 is the 20-hour bit (20 to 23 hours). The CENT bit,
bit 7 of the Months Register, can be written by the user. This bit changes its state when the years counter
transitions from 99 to 00.
The calendar logic is designed to automatically compensate for leap years. For every year value that is either 00 or
a multiple of 4 the device adds a 29
023Fh
ADDR
0200h
0201h
0202h
0203h
0204h
0205h
ADDR
022Fh
ADDR
041Fh
0228h
0230h
0237h
0238h
0400h
0401h
0403h
0404h
0405h
0406h
0407h
0408h
—
—
—
—
—
CENT
b7
b7
b7
0
0
0
0
0
0
12/24
b6
b6
b6
0
0
0
0
10yrs
Temperature Conversion Length Low Byte
(no function; all of these bytes read 00h)
10 min.
AM/PM
Temperature Counter Reset Low Byte
20hr
10s
b5
b5
b5
0
0
0
th
10 Date
(no function; undefined read)
(no function; undefined read)
of February. This works correctly up to (but not including) the year 2100.
10m.
10hr
b4
b4
b4
Eighth Byte
Eighth Byte
delay value
Temperature Conversion Length High Byte
First Byte
First Byte
Temperature Counter Reset High Byte
—
—
12 of 49
b3
b3
b3
Single Seconds
Single Minutes
Single Months
Single Hours
Single Years
b2
b2
b2
Single Date
b1
b1
b1
b0
b0
b0
Password
Password
Function
Function
Access
Access
Read
(N/A)
(N/A)
(N/A)
Full
t
SP
R/W; R/W
R/W; R/W
Access*
Access*
R/W; R
W; —
W; —
R; R
R; R
R; R