DS1318 Datasheet, PDF (12/15 Pages) Dallas Semiconductor – Parallel-Interface Elapsed Time Counter

Parallel-Interface Elapsed Time Counter
BIT 7
PRS3
BIT 6
PRS2
BIT 5
PRS1
BIT 4
PRS0
Bits 7 to 4: Periodic Rate Select (PRS3–PRS0). When
the oscillator is enabled (ENOSC = 1) the PF flag is set
at the rates determined by the following table:
Periodic Flag Frequency When ENOSC = 1
PRS3 PRS2 PRS1 PRS0
0
0
0
0
0
0
0
1
0
0
1
0
0
0
1
1
0
1
0
0
0
1
0
1
0
1
1
0
0
1
1
1
1
0
0
0
1
0
0
1
1
0
1
0
1
0
1
1
1
1
0
0
1
1
0
1
1
1
1
0
1
1
1
1
PERIODIC FLAG
FREQUENCY
Periodic Flag Not Set
4096Hz
2048Hz
1024Hz
512Hz
256Hz
128Hz
8Hz
4Hz
2Hz
1Hz
1/64Hz
(Once per 1.067 Minutes)
1/4096Hz
(Once per 1.138 Hours)
1/65536Hz
(Once per 1.318 Days)
1/524288Hz
(Once per 0.8669 Weeks)
1/2097152Hz
(Once per 24.27 Days)
Control Register B (0Bh)
BIT 3
SRS3
BIT 2
SRS2
BIT 1
SRS1
BIT 0
SRS0
Bits 3 to 0: Square-Wave Rate Select (SRS3–SRS0).
When the oscillator is enabled (ENOSC = 1) and run-
ning, and the square-wave pin is enabled (SQWE = 1),
the SQW pin outputs a square-wave signal determined
by the SRS bits according to the following table:
Square-Wave Output Frequency When SQWE = 1,
ENOSC = 1
SRS3 SRS2 SRS1 SRS0
0
0
0
0
0
0
0
1
0
0
1
0
0
0
1
1
0
1
0
0
0
1
0
1
0
1
1
0
0
1
1
1
1
0
0
0
1
0
0
1
1
0
1
0
1
0
1
1
1
1
0
0
1
1
0
1
1
1
1
0
1
1
1
1
SQUARE-WAVE OUTPUT
FREQUENCY (Hz)
32,768
8192
4096
2048
1024
512
256
128
64
32
16
8
4
2
1
0.5
12 ____________________________________________________________________