EM91420 SERIES
TONE/PULSE SWITCHABLE DIALER WITH LCD INTERFACE
AND DUAL-TONE MELODY GENERATOR
Operating flow chart
HKS=Lo
HF
HF
4
On-hook
Hand-free State
1
On-hook State
HKS=Hi
2
Off-hook State
HF
HF
HD
HF
HD
6
On-hook
Hold-line State
HD
HKS=Hi
HKS=Lo
5
Off-hook
Hold-line State
HD
HKS=Lo
HKS=Hi
HD
HF
3
Off-hook
Hand-free State
<Note> : HF = Handfree
HD = Hold
Truth table
Operating state
Input/Output pin level
HKS
PO
XMUTE
HFO
(0) On-hook, idle state
H
F
F
L
(1) Off-hook line
L
F
F
L
(2) Off-hook, HF line
L
F
F
H
(3) On-hook, HF line
H
F
F
H
(4) Off-hook, HD line
L
F
L
L
(5) On-hook, HD line
H
F
L
L
Note : F=floating (high impedance); H=logic “High”; L=logic “Low” level.
HDO
L
L
L
L
H
H
Music on Hold
EM91420 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.
1
bit 0
bit2
bit3
data bits
bit4
bit5
0
stop bits
1
ready
0
start bits
bit1
* This specification are subject to be changed without notice.
10.1.1997
8
EMC [ ELAN MICROELECTRONICS CORP ]
