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12-07-0001

PT0321-6

07/04/12

8

PT7C433833

Real-time Clock Module (I

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 I

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

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)

0

12, /24

H20 or

P, /A

H10

H8

H4

H2

H1

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

Years (00-99)

Y80

Y40

Y20

Y10

Y8

Y4

Y2

Y1

07

Control

*3

OUT

*4

0

OSF

SQWE

*5

0

0

RS1

*6

RS0

*6

08~3F

RAM

*7

-

-

-

-

-

-

-

-

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.