Silan

Semiconductors

SC9256

HANGZHOU SILAN MICROELECTRONICS JOINT-STOCK CO.,LTD

REV: 1.0

2002.01.30.

6

FUNCTION DESCRIPTION

Serial I/O ports

As the block diagram shows, the functions are controlled by setting data in the 48 bits contained in each of the 2

sets

of 24 bit registers. Each bit of data in these register is transferred through the serial ports between the

controller and the DATA, CLOCK and PERIOD pins. Each serial transfer consists of a total of 32 bits, with 8

address bits and 24 data bits.

Since all functions are controlled in units of registers, the explanation in this manual focuses on the 8 bit address

and functions of each register.

These registers consist of 24 bits and are selected by an 8 bit address.

A list of the address assignment for each register is given below under register assignments.

Register

Address

Contents of 24 bits

No. of bit

Input

register 1

D0H

PLL divisor setting

Reference frequency setting

PLL input and mode setting

Crystal oscillator selection

16

4

2

2

total 24

Input

register 2

D2H

General=purpose counter control (including lock detection bit

control)

I/O port and general-purpose counter switching bits

I/O-5/CLK pin switching bit

DO pin control

Test bit

I/O port control (also used as general-purpose counter input

selection bits)

Output data

4

3

1

1

1

5

9

total 24

Output

register 1

D1H

General-purpose counter numeric data

Not used

22

2

total 24

Output

register 2

D3H

Lock detection data

I/O port control data

Output data

Input data (undefined during output port selection)

Not used

5

5

4

5

5

total 24

When the PERIOD signal falls, the input data are latched in register 1 or register 2 and the function is performed.

When the CLOCK signal falls for 9 time, the output data are latched in parallel in the output registers. The data

are subsequently output serially from the data pin.