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PT0206(08/09)
Ver: 3
4
Data Sheet
PT7C4307
Real-time Clock Module (I
2C Bus)
Function Description
Clock function
CPU can read or write data including the year (last two digits),
month, date, day, hour, minute, and second. Any (two-digit)
year that is a multiple of 4 is treated as a leap year and
calculated automatically as such until the year 2099.
Programmable square wave output
A square wave output enable bit controls square wave output
at pin 7. 4 frequencies are selectable: 1, 4.096k, 8.192k,
32.768k Hz.
Interface with CPU
Data is read and written via the I
2C bus interface using two
signal lines: SCL (clock) and SDA (data).
Since the output of the I/O pin SDA is open drain, a pull-up
resistor should be used on the circuit board if the CPU output
I/O is also open drain.
The SCL's maximum clock frequency is 400 kHz, which
supports the I
2C bus's high-speed mode.
Oscillator enable/disable
Oscillator can be enabled or disabled by /EOSC bit. But time
count chain does not shut down when the bit is logic 1.
RAM
56
×8 nonvolatile RAM are available for customer use.
Registers
Allocation of registers
Register definition
Addr.
(hex)
*1
Function
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
00
Seconds (00-59)
/EOSC
*2
S40
S20
S10
S8
S4
S2
S1
01
Minutes (00-59)
0
M40
M20
M10
M8
M4
M2
M1
02
Hours (00-23 / 01-12)
0
12, /24
H20 or
P, /A
H10
H8
H4
H2
H1
03
Days of the week (01-07)
0
W4
W2
W1
04
Dates (01-31)
0
D20
D10
D8
D4
D2
D1
05
Months (01-12)
0
MO10
MO8
MO4
MO2
MO1
06
Years (00-99)
Y80
Y40
Y20
Y10
Y8
Y4
Y2
Y1
07
Control
*3
OUT
*4
0
SQWE
*5
0
RS1
*6
RS0
*6
08~3F
RAM
*7
-
Caution points:
*1. PT7C4307 uses 6 bits for address. That is if write data to 41H, the data will be written to 01H address register.
*2. Oscillator Enable bit. When this bit is set to 1, oscillator is stopped but time count chain is still active.
*3. Control register was used to select SQW/OUT pin output square wave with one of 4 kinds of frequency or DC level.
*4. Control SQW/OUT pin output DC level when square wave is disabled.
*5. Square wave outputs enable at SQW/OUT pin.
*6. Square wave output frequency select.
*7. PT7C4307 has 56
×8 static RAM for customer use. It is volatile RAM.
*8. All bits marked with "0" are read-only bits. Their value when read is always "0". All bits marked with "-" are customer using
space.