SM8230A

SEIKO NPC CORPORATION —5

FUNCTIONAL DESCRIPTION

Serial Interface

Data is transferred in 16-bit units by writing commands over a 3-line serial interface comprising OE (output

enable), SCL (serial clock) and SD (serial data input). Note that data transfer is unidirectional; no data is output

from the SM8230A. The operating sequence is described below.

Command transfer

Data can be transferred when OE goes LOW. Data is transferred in 16-bit units in sync with the rising edge of

the SCL clock.

Note that when OE is LOW and both SD and SCL are tied LOW, the current consumption is less than 1µA

(standby mode).

The internal states are undefined when power is first applied.

DTMF analog signal output

Data transfer stops and DTMF analog signal output starts when OE goes HIGH, as shown in figure 2.

Figure 1. Serial interface connection example

Figure 2. Serial data transfer timing

(Clock)

Port

Serial Clock

Serial Data

CPU

CLK

OE

SCL

SD

BZH

BZL

R

Piezo Buzzer

SM8230

SCL

SD

BZL

12

345

678

9

10

11

12

13

14

15

16

MSB

LSB

BZH

OE

0

0

CK1 CK0 FH1 FH0 GH3 GH2 GH1 GH0 FL1 FL0 GL3 GL2 GL1 GL0

Piezo buzzer

output

Serial data transmission

Low frequency

group output

High frequency

group output

b15 b14 b13 b12 b11 b10 b9

b8

b7

b6

b5

b4

b3

b2

b1

b0