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PT7C433833 Datasheet, PDF (8/17 Pages) Pericom Semiconductor Corporation – Real-time Clock Module (I2C Bus)
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PT7C433833
Real-time Clock Module (I2C Bus)
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Function Description
Overview of Functions
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 2100.
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 I2C 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 I2C bus's high-speed mode.
Oscillator enable/disable
Oscillator can be enabled or disabled by /EOSC bit.
Registers
Allocation of registers
Addr.
(hex)*1
Function
Register definition
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)
H20 or
0
12, /24
H10
H8
H4
H2
H1
P, /A
03 Days of the week (01-07)
0
0
0
0
0
W4
W2
W1
04 Dates (01-31)
0
0
D20
D10
D8
D4
D2
D1
05 Months (01-12)
0
0
0
MO10 MO8
MO4
MO2
MO1
06
07
08~3F
Years (00-99)
Control*3
RAM*7
Y80
Y40
OUT*4
0
-
-
Y20
Y10
Y8
OSF SQWE*5
0
-
-
-
Y4
Y2
Y1
0
RS1*6
RS0*6
-
-
-
Caution points:
*1. PT7C4338 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. PT7C4338 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.
12-07-0001
PT0321-6 07/04/12
8
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