HT1380A HOLTEK [Holtek Semiconductor Inc], HT1380A Datasheet - Page 5

• Manufacturer Part Number: HT1380A
• Description: Serial Timekeeper Chip
• Manufacturer: HOLTEK [Holtek Semiconductor Inc]

Functional Description
The HT1380A/HT1381A mainly contains the
following internal elements: a data shift register array
to store the clock/calendar data, command control
logic, oscillator circuit and read timer clock. The
clock is contained in eight read/write registers as
shown below. Data contained in the clock register is
in binary coded decimal format.
Two modes are available for transferring the data
between the microprocessor and the HT1380A/
HT1381A. One is in single-byte mode and the other is
in multiple-byte mode.
The HT1380A/HT1381A also contains two additional
bits, the clock halt bit (CH) and the write protect bit (WP).
These bits control the operation of the oscillator and so
Note: ″x″ stands for don′t care
The following table shows the register address and its data format:
CH=0 oscillator enabled
CH=1 oscillator disabled
WP=0 register data can be written in
WP=1 register data can not be written in
Rev. 1.00
Select Read or Write Cycle
Specify the Register to be Accessed
Clock Halt Flag
For IC Test Only
Select Single Byte or Burst Mode
Seconds
Minutes
Hours
Date
Month
Day
Year
Write Protect
CH: Clock Halt bit
WP: Write protect bit
Register
Name
Function Description
Range
00~59
00~59
01~12
00~23
01~31
01~12
01~07
00~99
00~80
Data
WP
CH
12\
D7
24
0
0
0
0
D6
10 YEAR
0
0
0
0
0
10 SEC
10 MIN
C7
—
—
C
1
1
D5
AP
10
10 DATE
0
0
Register Definition
10M
C6
—
—
—
HR
HR
D4
ALWAYS ZERO
0
0
0
D3
5
C5
—
—
—
0
1
data can be written to the register array. These two
bits should first be specified in order to read from and
write to the register array properly.
Command Byte
For each data transfer, a Command Byte is initiated
to specify which register is accessed. This is to
determine whether a read, write, or test cycle is
operated and whether a single byte or burst mode
transfer is to occur. Refer to the table shown below
and follow the steps to write the data to the chip. First
give a Command Byte of HT1380A/HT1381A, and
then write a data in the register.
This table illustrates the correlation between
Command Byte and their bits:
D2
MONTH
Bit 7 of Reg2: 12/24 mode flag
Bit 5 of Reg2: AM/PM mode defined
HOUR
YEAR
DATE
SEC
MIN
DAY
D1
C4
—
—
—
Command Byte
1
1
bit 7=1, 12-hour mode
bit 7=0, 24-hour mode
AP=1 PM mode
AP=0 AM mode
D0
C3
A2
—
—
1
x
Address
A2~A0
000
001
010
100
101
011
110
111
HT1380A/HT1381A
C2
A1
—
—
1
x
R/W
Bit
W
W
W
W
W
W
W
W
R
R
R
R
R
R
R
R
C1
A0
—
—
1
x
June 15, 2012
Command
10000000
10000001
10000010
10000100
10000101
10001000
10001001
10001010
10000011
10000110
10000111
10001011
10001100
10001101
10001110
10001111
Byte
R/W
C0
—
—
1
x