EM91440 SERIES

TONE/PULSE SWITCHABLE DIALER WITH LCD INTERFACE

AND DUAL-TONE MELODY GENERATOR

8

* This specification are subject to be changed without notice.

10.1.1997

Operating flow chart

<Note> : HF = Handfree

HD = Hold

Truth table

Operating state

Input/Output pin level

HKS

PO

XMUTE

HFO

HDO

(0) On-hook, idle state

H

F

F

L

L

(1) Off-hook line

L

F

F

L

L

(2) Off-hook, HF line

L

F

F

H

L

(3) On-hook, HF line

H

F

F

H

L

(4) Off-hook, HD line

L

F

L

L

H

(5) On-hook, HD line

H

F

L

L

H

Note : F=floating (high impedance); H=logic “High”; L=logic “Low” level.

Music on Hold

EM91440 series built-in a melody generator to generate dual-tone music on DTMF output pin. The music is

designed for telephone line at line holding.

SDO (Serial Data Output) function

The SDO is serial data output which format is same as UART protocol. SDO function is designed to drive LCD

driver and voice synthesizer. So the dialing numbers can be display on LCD screen with EM32100 (or EM32116

). The SDO signal consists of two start bits, six data bits and two stop bits. Each bit time is about 3.9 ms (256 Hz)

and output sequences are following by start bits, data bits (LSB to MSB) and stop bits.

0

1

bit 0

bit1

bit2

bit3

bit4

bit5

ready

start bits

data bits

0

1

stop bits

1

On-hook State

2

Off-hook State

4

On-hook

Hand-free State

HKS=Lo

HKS=Lo

HKS=Hi

HF

HF

HD

HF

HD

6

On-hook

Hold-line State

3

Off-hook

Hand-free State

HF

HF

HF

HD

HKS=Hi

HKS=Lo

5

Off-hook

Hold-line State

HD

HD

HKS=Hi