as2578 austriamicrosystems, as2578 Datasheet - Page 6

• Manufacturer Part Number: as2578
• Description: Telephone Controller With 13 Memories And 2-wire Bus
• Manufacturer: austriamicrosystems

Data Sheet
data transmission and await the stop condition to return
to the standby power mode.
Frequency Comparator
The frequency comparator monitors that the ring signal
is in the limits as shown in figure 4.
Rev. 3
When a continious valid ring signal is present for 80 ms,
the melody generator is activated and remains active
until two or more periods of the ring signal are missing.
SDA
SDA
SCL from
master
Data out
from Tx
Data out
from Rx
SCL
SCL
Figure 3 Acknowledge Response From Receiver
Figure 4 Detection Window of Ringing Signal
20
Figure 2 Definition of Start and Stop
start
start
bit
30
Figure 1 Data Validity
stable
DETECT
data
MUST
40
1
change
data
50
60
frequency
8
70
acknowledge
Ring
Tol.
(Hz)
stop
9
bit
6
Tone Generator
The tone generator incorporates the DTMF tones and 3
basic frequencies for the tone ringer.
DTMF
The DTMF generator provides 8 frequencies, namely:
Low group
High group
The MF tones are in accordance with CEPT
recommendations.
Tone Ringer (Melody)
The three basic frequencies of the melodies are:
F1 = 800 Hz, F2 = 1067 Hz, and F3 = 1333 Hz ( 5%).
The repetition rate can be set via key procedures or by
pin options as follows:
Repetition rate means that a sequence of 6 frequencies
is repeated 1 to 10 times within 1 sec. For LM code 1 a
pause of 50 ms is inserted between the frequencies to
allow a better recognition of the melodies.
The sequence of the frequencies is controlled by the
sequence register as follows:
The volume of the melodies (MO output) can be set as
follows:
Row 1
Row 2
Row 3
Row 4
Col. 1
Col. 2
Col. 3
Col. 6
LM code
LM code
1
2
3
4 (default)
1
2 (default)
3
4
Sequence
1209 Hz
1336 Hz
1477 Hz
1633 Hz
697 Hz
770 Hz
852 Hz
941 Hz
F1 F2 F3 F1 F2 F3 …
- 17.5 dB
- 11.5 dB
- 5.5 dB
Volume
Repetition rate
0 dB
10 times
4 times
7 times
1 time
(AS2578B only)
5.5 dB
Steps
6 dB
6 dB
(50 ms pause)
AS2578 /B
March 1997