Rainbow Electronics DS2422 - Manual (Page 12)

DS2422
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ADDR b7 b6 b5 b4 b3 b2 b1 b0 Function Access*
0228h First Byte Read
— — Access W; —
022Fh Eighth Byte Password
0230h First Byte Full
— — Access W; —
0237h Eighth Byte Password
0238h
— (no function; all of these bytes read 00h) (N/A) R; R
023Fh
Figure 8B. DS2422 Trim Register Page Map
ADDR b7 b6 b5 b4 b3 b2 b1 b0 Function Access*
0400h delay value t
SP
R/W; R
0401h
— (no function; undefined read) (N/A) R; R
0403h
0404h
Temperature Counter Reset Low Byte
0405h 0 0 0 Temperature Counter Reset High Byte
R/W; R/W
0406h Temperature Conversion Length Low Byte
0407h 0 0 0 Temperature Conversion Length High Byte
R/W; R/W
0408h
— (no function; undefined read) (N/A) R; R
041Fh
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/alarm 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 and RTC Alarm Register Bitmap
ADDR b7 b6 b5 b4 b3 b2 b1 b0
0200h 0 10s Single Seconds
0201h 0 10 min. Single Minutes
0202h 0 12/24 20hr
AM/PM
10hr
Single Hours
0203h 0 0 10 Date Single Date
0204h CENT 0 0 10m. Single Months
0205h 10yrs Single Years
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
th of February. This works correctly up to (but not including) the year 2100.