Rainbow Electronics DS1372 - Manual (Page 6)

DS1372
Alarm Operation
The alarm counter is a 24-bit counter in the address
range 04h–06h. When the alarm counter is written, a
seed register is written with the alarm counter value.
When the alarm counter enable (ACE) bit in the Control
Register is set to 1, the counter begins counting down
from the seed value. When the counter reaches zero, it
sets the AF bit in the Status Register, if the AF bit is not
already set. If the AIE and INTCN bits are both set to a
logic 1, the SQW/INT pin goes low and remains low
until AF is written to logic 0. The counter is then
reloaded with the seed value and the countdown
restarts. When the counter is read, the current counter
value is latched into a register, which is output on the
serial data line while the counter continues to decre-
ment. The counter is disabled if the seed value is zero
or if ACE = 0. Whenever the ACE is set from 0 to 1, the
counter is reloaded with the current seed value and the
counter begins to count down. Note: When initializing
or changing the alarm value, the ACE bit should be
enabled after writing the alarm counter bytes.
6 _______________________________________________________________________________________
ADDRESS REGISTER BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0
00h Clock — Seconds Counter Byte 0 LSB
01h Clock — Seconds Counter Byte 1 —
02h Clock — Seconds Counter Byte 2 —
03h Clock MSB Seconds Counter Byte 3 —
04h Alarm — Alarm Counter Byte 0 LSB
05h Alarm — Alarm Counter Byte 1 —
06h Alarm MSB Alarm Counter Byte 2 —
07h Control EOSC ACE 0 0 INTCN RS2 RS1 AIE
08h Status OSF 0 0 0 0 0 0 AF
09h ID Model Number
0Ah ID Serial Number Byte 0
0Bh ID Serial Number Byte 1
0Ch ID Serial Number Byte 2
0Dh ID Serial Number Byte 3
0Eh ID Serial Number Byte 4
0Fh ID Serial Number Byte 5
10h ID CRC
Table 1. DS1372 Address Map
Note: Unless otherwise specified, the states of the registers are undefined when power is first applied. Bits shown as 0 always read
back as 0.
I
2
C, 32-Bit, Binary Counter Clock with 64-Bit ID