DS1337_09 Datasheet, PDF (8/16 Pages) Maxim Integrated Products – I2C Serial Real-Time Clock

DS1337 I²C Serial Real-Time Clock
ADDRESS MAP
Table 2 shows the address map for the DS1337 registers. During a multibyte access, when the address pointer
reaches the end of the register space (0Fh) it wraps around to location 00h. On an I²C START, STOP, or address
pointer incrementing to location 00h, the current time is transferred to a second set of registers. The time
information is read from these secondary registers, while the clock may continue to run. This eliminates the need
to re-read the registers in case of an update of the main registers during a read.
Table 2. Timekeeper Registers
ADDRESS
00H
BIT 7
0
BIT 6
BIT 5
BIT 4
10 Seconds
01H
0
10 Minutes
02H
0
12/24
AM/PM
10 Hour
10 Hour
03H
0
0
0
0
BIT 3
0
BIT 2
BIT 1
Seconds
Minutes
Hour
Day
BIT 0
FUNCTION
Seconds
Minutes
Hours
Day
RANGE
00–59
00–59
1–12
+AM/PM
00–23
1–7
04H
05H
06H
07H
08H
09H
0AH
0BH
0CH
0DH
0EH
0FH
0
Century
A1M1
A1M2
A1M3
A1M4
A2M2
A2M3
A2M4
EOSC
OSF
0
10 Date
0
0
10 Year
10 Month
10 Seconds
12/24
10 Minutes
AM/PM
10 Hour
10 Hour
DY/DT
10 Date
12/24
10 Minutes
AM/PM
10 Hour
10 Hour
DY/DT
10 Date
0
0
RS2
RS1
0
0
0
0
Date
Month
Year
Seconds
Minutes
Hour
Day
Date
Minutes
Hour
Day
Date
INTCN A2IE
0
A2F
A1IE
A1F
Date
Month/
Century
Year
Alarm 1
Seconds
Alarm 1
Minutes
Alarm 1
Hours
Alarm 1
Day
Alarm 1
Date
Alarm 2
Minutes
Alarm 2
Hours
Alarm 2
Day
Alarm 2
Date
Control
Status
01–31
01–12 +
Century
00–99
00–59
00–59
1–12 +
AM/PM
00–23
1–7
01–31
00–59
1–12 +
AM/PM
00–23
1–7
01–31
—
—
Note: Unless otherwise specified, the state of the registers is not defined when power is first applied or V_CC falls below the V_OSC.
I²C INTERFACE
The I²C interface is accessible whenever V_CC is at a valid level. If a microcontroller connected to the DS1337 resets
while reading from the DS1337 during an I²C read, the two could become unsynchronized. The microcontroller must
terminate the last byte read with a Not-Acknowledge (NACK) to properly terminate the read. When the microcontroller
resets, the DS1337 I²C interface may be placed into a known state by toggling SCL until SDA is observed to be at a
high level. At that point the microcontroller should pull SDA low while SCL is high, generating a START condition.
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