SM8230A_06 Datasheet, PDF (5/8 Pages) NEC – Tone Dialer with Built-in Piezo Driver

SM8230A
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.
CPU
Port
Serial Clock
Serial Data
(Clock)
OE
BZH
SCL
R
SD SM8230
CLK
BZL
Piezo Buzzer
Figure 1. Serial interface connection example
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.
OE
SCL
SD
BZL
BZH
12
345
Serial data transmission
6 7 8 9 10 11 12 13 14 15 16
Piezo buzzer
output
b15 b14 b13 b12 b11 b10 b9 b8 b7 b6 b5 b4 b3 b2 b1 b0
0 0 CK1 CK0 FH1 FH0 GH3 GH2 GH1 GH0 FL1 FL0 GL3 GL2 GL1 GL0
MSB
LSB
Low frequency
group output
High frequency
group output
Figure 2. Serial data transfer timing
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