ETC SI2400-KS

Si2400
V. 2 2 B I S I S O M O D E M ™ W I T H I N T E G R A T E D G L O B A L DA A
Features
!
!
!
!
Integrated DAA
2400 bps: V.22bis
"
Capacitive Isolation
"
1200 bps: V.22, V.23, Bell 212A
"
Parallel Phone Detect
"
300 bps: V.21, Bell 103
"
Globally Compliant Line Interface
"
V.25 Fast Connect and V.23 Reversing
"
Overcurrent Protection
"
SIA and other security protocols
Caller ID Detection and Decode
DTMF Tone Gen./Detection
3.3 V or 5.0 V Power
UART with Flow Control
!
!
!
!
01
AT Command Set Support
Integrated Voice Codec
PCM Data Pass-Through Mode
HDLC Framing in Hardware
Call Progress Support
i3
!
5
"
S
!
i2
40
0
Data Modem Formats
S
!
Ordering Information
See page 71.
Applications
Pin Assignments
!
!
Set Top Boxes
Power Meters
!
!
Security Systems
ATM Terminals
!
!
Medical Monitoring
Point-of-Sale
Description
The Si2400 ISOmodem™ is a complete modem chipset with integrated
direct access arrangement (DAA) that provides a programmable line
interface to meet global telephone line requirements. Available in two 16pin small outline (SOIC) packages, it eliminates the need for a separate
DSP data pump, modem controller, analog front end (AFE), isolation
transformer, relays, opto-isolators, 2- to 4-wire hybrid, and voice codec.
The Si2400 is ideal for embedded modem applications due to its small
board space, low power consumption, and global compliance.
Functional Block Diagram
µ Controller
(AT Decoder
Call Progress)
DSP
(Data Pump)
Control
Interface
CTS
Audio
Codec
CLKOUT
XTALI
XTALO
Clock
Interface
RX
Isolation Interface
RESET
EOFR/GPIO1
AIN/GPIO2
ESC/GPIO3
ALERT/GPIO4
Si3015
Isolation Interface
UART
TXD
RXD
MUX
Si2400
Hybrid
and
DC
Termination
FILT
FILT2
REF
DCT
Si2400
XTALI
1
16
EOFR/GPIO1
XTALO
2
15
AIN/GPIO2
CLKOUT
3
14
ESC/GPIO3
VD
4
13
ISOB
TXD
5
12
GND
RXD
6
11
C1A
CTS
7
10
ALERT/GPIO4
RESET
8
9
AOUT
Si3015
QE2
1
16
FILT2
DCT
2
15
FILT
IGND
3
14
RX
C1B
4
13
REXT
RNG1
5
12
REXT2
RNG2
6
11
REF
QB
7
10
VREG2
QE
8
9
VREG
Patents pending
VREG2
REXT
REXT2
Ring Detect
Off-Hook
RNG1
RNG2
QB
QE
QE2
AOUT
Rev. 0.95 4/00
Copyright © 2000 by Silicon Laboratories
Si2400-DS095
S i2 40 0
2
Rev. 0.95
Si2400
TA B L E O F C O N T E N T S
Section
Page
Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Typical Application Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Typical Application Circuit Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Bill of Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Analog Input/Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Digital Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configurations and Data Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Low Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Global DAA Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Parallel Phone Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Carrier Detect/Loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Overcurrent Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Caller ID Decoding Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tone Generation and Tone Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PCM Data Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Analog Codec . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
V.23 Operation/V.23 Reversing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
V.42 HDLC Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fast Connect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Clock Generation Subsystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
AT Command Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Command Line Execution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
< CR > End Of Line Character . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
AT Command Set Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Extended AT Commands for the Alarm Industry . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Modem Result Codes and Call Progress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Low Level DSP Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
S Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Appendix A—DAA Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Appendix B—Typical Modem Applications Examples . . . . . . . . . . . . . . . . . . . . . . . . .
Appendix C—UL1950 3rd Edition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ordering Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Package Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Contact Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Rev. 0.95
4
9
9
10
11
12
13
13
14
15
15
18
18
18
19
19
21
21
22
23
23
25
25
25
25
27
30
32
35
62
67
68
71
72
76
3
S i2 40 0
Electrical Specifications
Table 1. Recommended Operating Conditions
Symbol
Test Condition
Min2
Typ
Max2
Unit
Ambient Temperature
TA
K-Grade
0
25
70
°C
Ambient Temperature
TA
B-Grade
–40
25
85
°C
Si2400 Supply Voltage, Digital3
VD
3.0
3.3/5.0
5.25
V
Parameter1
Notes:
1. The Si2400 specifications are guaranteed when the typical application circuit (including component tolerance) and any
Si2400 and any Si3015 are used. See Figure 3 on page 9 for typical application circuit.
2. All minimum and maximum specifications are guaranteed and apply across the recommended operating conditions.
Typical values apply at nominal supply voltages and an operating temperature of 25 °C unless otherwise stated.
3. The digital supply, VD, can operate from either 3.3 V or 5.0 V. The Si2400 interface supports 3.3 V logic when operating
from 3.3 V. The 3.3 V operation applies to both the serial port and the digital signals CTS, CLKOUT, GPIO1–4, and
RESET.
Table 2. DAA Loop Characteristics
(VD = 3.0 to 3.6 V or 4.75 to 5.25 V, TA = 0 to 70°C for K-Grade, TA = –40 to 85°C for B-Grade)
Parameter
Symbol
Test Condition
Min
Typ
Max
Unit
DC Termination Voltage
VTR
IL = 20 mA, ACT = 1
DCT = 11 (CTR21)
—
—
7.5
V
DC Termination Voltage
VTR
IL = 42 mA, ACT = 1
DCT = 11 (CTR21)
—
—
14.5
V
DC Termination Voltage
VTR
IL = 50 mA, ACT = 1
DCT = 11 (CTR21)
—
—
40
V
DC Termination Voltage
VTR
IL = 60 mA, ACT = 1
DCT = 11 (CTR21)
40
—
—
V
DC Termination Voltage
VTR
IL = 20 mA, ACT = 0
DCT = 01 (Japan)
—
—
6.0
V
DC Termination Voltage
VTR
IL = 100 mA, ACT = 0
DCT = 01 (Japan)
11
—
—
V
DC Termination Voltage
VTR
IL = 20 mA, ACT = 0
DCT = 10 (FCC)
—
—
7.5
V
DC Termination Voltage
VTR
IL = 100 mA, ACT = 0
DCT = 10 (FCC)
12
—
—
V
On Hook Leakage Current
ILK
VBAT = –48 V
—
—
1
µA
Operating Loop Current
ILP
FCC/Japan Modes
13
—
120
mA
Operating Loop Current
ILP
CTR21
13
—
60
mA
—
—
20
µA
Ring Detect Voltage
VRD
RT = 0
11
—
22
VRMS
Ring Detect Voltage
VRD
RT = 1
17
—
33
VRMS
FR
15
—
68
Hz
REN
—
—
0.2
DC Ring Current
Ring Frequency
Ringer Equivalence Number*
*Note: C15, R14, Z2, and Z3 not installed.
4
Rev. 0.95
Si2400
Table 3. DC Characteristics
(VD = 4.75 to 5.25 V, TA = 0 to 70°C for K-Grade, TA = –40 to 85°C for B-Grade)
Parameter
Symbol Test Condition
Min
Typ
Max
Unit
High Level Input Voltage
VIH
3.5
—
—
V
Low Level Input Voltage
VIL
—
—
0.8
V
High Level Output Voltage
VOH
IO = –2 mA
2.4
—
—
V
Low Level Output Voltage
VOL
IO = 2 mA
—
—
0.4
V
Low Level Output Voltage, GPIO1–4
VOL
IO = 40 mA
—
—
0.6
V
–10
—
10
µA
VD pin
—
28
32
mA
ID
VD pin
—
16
19
mA
Power Supply Current, Wake-On-Ring (ATZ)
ID
VD pin
—
10
11
mA
Power Supply Current, Total Power Down
ID
VD pin
—
60
105
µA
Input Leakage Current
IL
Power Supply Current, Digital*
ID
Power Supply Current, DSP Power Down*
*Note: Specifications assume MCKR = 0 (default). Typical value is 4 mA lower when MCKR = 1 and 6 mA lower when
MCKR = 2,3.
Measurements are taken with inputs at rails and no loads on outputs.
Table 4. DC Characteristics
(VD = 3.0 to 3.6 V, TA = 0 to 70°C for K-Grade, TA = –40 to 85°C for B-Grade)
Parameter
Symbol Test Condition
Min
Typ
Max
Unit
High Level Input Voltage
VIH
2.1
—
—
V
Low Level Input Voltage
VIL
—
—
0.8
V
High Level Output Voltage
VOH
IO = –2 mA
2.4
—
—
V
Low Level Output Voltage
VOL
IO = 2 mA
—
—
0.35
V
Low Level Output Voltage, GPIO1–4
VOL
IO = 20 mA
—
—
0.6
V
–10
—
10
µA
Input Leakage Current
IL
Power Supply Current, Digital
ID
VD pin
—
15
21
mA
Power Supply Current, DSP Power Down
ID
VD pin
—
9
14
mA
Power Supply Current, Wake-On-Ring
ID
VD pin
—
5
8
mA
Power Supply Current, Total Power Down
ID
VD pin
—
40
55
µA
*Note: Specifications assume MCKR = 0 (default). Typical value is 2 mA lower when MCKR = 1 and 3 mA lower when
MCKR = 2,3.
Measurements are taken with inputs at rails and no loads on outputs.
TIP
+
600 Ω
Si3015
IL
VTR
10 µF
–
RING
Figure 1. Test Circuit for Loop Characteristics
Rev. 0.95
5
S i2 40 0
Table 5. DAA AC Characteristics
(VD = 3.0 to 3.6 V or 4.75 to 5.25 V, TA = 0 to 70°C for K-Grade, TA = –40 to 85°C for B-Grade)
Parameter
Symbol
Test Condition
Min
Typ
Max
Unit
Transmit Frequency Response
Low –3 dB Corner
—
5
—
Hz
Receive Frequency Response
Low –3 dB Corner
—
5
—
Hz
VFS
—
0.6
—
dBm
Receive Full Scale Level
VFS
—
0.6
—
dBm
Dynamic Range3,4
DR
ACT = 0, DCT = 10 (FCC)
IL = 100 mA
—
82
—
dB
Dynamic Range3,5
DR
ACT = 0, DCT = 01 (Japan)
IL = 20 mA
—
82
—
dB
Dynamic Range3
DR
ACT = 1, DCT = 11(CTR21)
IL = 60 mA
—
82
—
dB
Transmit Total Harmonic Distortion4,6
THD
ACT = 0, DCT = 10 (FCC)
IL = 100 mA
—
–75
—
dB
Transmit Total Harmonic Distortion5,6
THD
ACT = 0, DCT = 01 (Japan)
IL = 20 mA
—
–75
—
dB
Receive Total Harmonic Distortion4,6
THD
ACT = 0, DCT = 01 (Japan)
IL = 20 mA
—
–75
—
dB
Receive Total Harmonic Distortion4,6
THD
ACT = 1, DCT = 11 (CTR21)
IL = 60 mA
—
–75
—
dB
DRCID
VIN = 1 kHz, –13 dB
—
60
—
dB
—
2.7
—
VPEAK
Transmit Full Scale Level1
1,2
Dynamic Range (Caller ID mode)
Caller ID Full Scale Level (0 dB gain)
1
VCID
Notes:
1. Measured at TIP and RING with 600 Ω termination.
2. Receive full scale level will produce –0.9 dBFS at TXD.
3. DR = VIN + 20*log (RMS signal/RMS noise). Measurement is 300 to 3400 Hz. Applies to both transmit and receive
paths. Vin = 1 kHz, –3dBFS, Fs = 10300 Hz
4. Vin = 1 KHz, –3 dB
5. Vin = 1 KHz, –9 dB
6. THD = 20*log (RMS distortion/RMS signal). Vin = 1 kHz, –3 dBFS, Fs = 10.3 kHz
6
Rev. 0.95
Si2400
Table 6. Voice Codec AC Characteristics
(VD = 3.0 to 3.6 V or 4.75 to 5.25 V, TA = 0 to 70°C for K-Grade, TA = –40 to 85°C for B-Grade)
Parameter
Symbol
Test Condition
Min
Typ
Max
Unit
AOUT Dynamic Range, APO = 0
VIN = 1 kHz
—
40
—
dB
AOUT THD, APO = 0
VIN = 1 kHz
—
–40
—
dB
AOUT Full Scale Level, APO = 0
—
0.7*VDD
—
VPP
AOUT Mute Level, APO = 0
—
60
—
dB
AOUT Dynamic Range, APO = 1,
VD = 4.75 to 5.25 V
VIN = 1 kHz, –3 dB
60
65
—
dB
AOUT Dynamic Range, APO = 1,
VD = 3 to 3.6 V
VIN = 1 kHz, –3 dB
55
65
—
dB
AOUT THD, APO = 1, VD = 4.75 to
5.25 V
VIN = 1 kHz, –3 dB
–55
–60
—
dB
AOUT THD, APO = 1, VD = 3 to 3.6 V
VIN = 1 kHz, –3 dB
–40
–60
—
dB
AOUT Full Scale Level, APO = 1
—
1.5
—
VPP
AOUT Mute Level, APO = 1
—
–65
—
dB
AOUT Resistive Loading, APO = 1
10
—
—
kΩ
AOUT Capacitive Loading, APO = 1
—
—
20
pF
AIN Dynamic Range, VD = 4.75 to
5.25 V
VIN = 1 kHz, –3 dB
60
65
—
dB
AIN Dynamic Range, VD = 3 to 3.6 V
VIN = 1 kHz, –3 dB
55
65
—
dB
AIN THD, VD = 4.75 to 5.25 V
VIN = 1 kHz, –3 dB
–55
–60
—
dB
AIN THD, VD = 3 to 3.6 V
VIN = 1 kHz, –3 dB
–40
–60
—
dB
—
2.8
—
VPP
AIN Full Scale
Level*
*Note: Receive full scale level will produce –0.9 dBFS at TXD.
Table 7. Absolute Maximum Ratings
Parameter
DC Supply Voltage
Input Current, Si2400 Digital Input Pins
Digital Input Voltage
Operating Temperature Range
Storage Temperature Range
Symbol
Value
Unit
VD
–0.5 to 6.0
V
IIN
±10
µA
VIND
–0.3 to (VD + 0.3)
V
TA
–10 to 100
°C
TSTG
–40 to 150
°C
Note: Permanent device damage may occur if the above Absolute Maximum Ratings are exceeded. Functional operation
should be restricted to the conditions as specified in the operational sections of this data sheet. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.
Rev. 0.95
7
S i2 40 0
Table 8. Switching Characteristics
(VD = 3.0 to 3.6 V or 4.75 to 5.25 V, TA = 0 to 70°C for K-Grade, TA = –40 to 85°C for B-Grade)
Parameter
Symbol
CLKOUT Output Clock Frequency
Min
Typ
Max
Unit
2.4576
—
39.3216
MHz
Baud Rate Accuracy
tbd
–1
—
1
%
Start Bit ↓ to CTS ↑
tsbc
—
1/(2*Baud Rate)
—
ns
CTS ↓ Active to Start Bit↓
tcsb
10
—
—
ns
RESET ↓ to RESET ↑
trs
5.0
—
—
msec
RESET ↑ Rise Time
trs2
—
—
100
ns
Note: All timing is referenced to the 50% level of the waveform. Input test levels are VIH = VD – 0.4 V, VIL = 0.4 V
Transmit Timing
TXD
Start
8-Bit Data
Mode (Default)
D0
D1
D2
D3
D4
D5
D6
D7
Stop
D0
D1
D2
D3
D4
D5
D6
D7
D8
TXD
9-Bit Data
Mode
Start
Stop
Receive Timing
RXD
8-Bit Data
Start
Mode(Default)
RXD
9-Bit Data
Mode
Start
D0
D1
D2
D3
D4
D5
D6
D7
Stop
D0
D1
D2
D3
D4
D5
D6
D7
D8
tcsb
tsbc
CTS
Note: Baud rates (programmed through register SE0) are as follows: 300, 1200, 2400, 9600, 19200,
230400, 245760, and 307200 Hz.
Figure 2. Asynchronous UART Serial Interface Timing Diagram
8
Rev. 0.95
Stop
Typical Application Circuit
VCC
C10
C27
No Ground Plane In DAA Section
C26
Q4
X1
1
R7
R15
C13
GPIO3/AIN/ESC
GPIO2/AIN/RXD2
GPIO1/AIN/TXD2/EOFR
R24
16
15
14
13
12
11
10
9
U2
AOUT
GPIO4/AIN/ALERT
C30
TSTA/QE2 TX/FILT2
TSTB/DCT NC/FILT
IGND
RX
C1B
REXT
RNG1
DCT/REXT2
RNG2
NC/REF
QB
NC/VREG2
QE
VREG
Si3015
C3
16
15
14
13
12
11
10
9
Q2
C5
R6
R11
C6
R18
R12
R2
Z1
C16
C14
+
R16
C1
Si2400
1
2
3
4
5
6
7
8
R17
GPIO1
GPIO2
GPIO3
ISOB
GND
C1A
GPIO4
AOUT
+
+
TXD
RXD
CTS
RESET
U1
XTALI
XTALO
CLKOUT
VD
TXD
RXD
CTS
RESET
C12
R19
CLKOUT
1
2
3
4
5
6
7
8
Q1
R5
R8
2
C20
R13
C2
Q3
Rev. 0.95
C8
FB2
R10
RING
D2
C19
C9
R26
C25
C32
RV1
RV2
R25
C18
D1
C7
C24
FB1
C4
Note 1: R12 R13 and C14 are onl required if complex AC termination is used ACT bit
C31
R9
TIP
1.
Note 2: See "Ringer Impedance" section for optional Czech Republic support.
Note 3: See "Billing Tone Immunit " section for optional billing tone filter German
S itzerland South Africa .
Note 4: See Appendix for applications requiring UL 1950 3rd edition compliance.
9
Si2400
Figure 3. Typical Application Circuit Schematic
S i2 40 0
Bill of Materials
Table 9. Global Component Values—Si2400 Chipset
Component
Value
Suppliers
C1,C4
150 pF, 3 kV, X7R,±20%
Novacap, Venkel, Johanson, Murata, Panasonic
C21
150 pF, 3 kV, X7R,±20%
Not Installed
C3
0.22 µF, 16 V, X7R, ±20%
C52
0.1 µF, 50 V, Elec/Tant/X7R, ±20%
C6,C10,C13,C16
0.1 µF, 16 V, X7R, ±20%
C7,C8
1800 pF, 250 V, X7R, ±20%
Novacap, Venkel, Johanson, Murata, Panasonic
C9
22 nF, 250 V, X7R, ±20%
Novacap, Venkel, Johanson, Murata, Panasonic
C12
1.0 µF, 16 V, Tant/X7R, ±20%
C142
0.68 µF, 16 V, X7R/Elec/Tant, ±20%
C18,C19
12 nF, 16 V, X7R, ±20%
C20
0.01 µF, 16 V, X7R, ±20%
C24,C25
1000 pF, 3 kV, X7R, ±10%
C26,C27
33 pF, 16 V, NPO, ±5%
C303
10 pF, 16 V, NPO, ±10%
Novacap, Venkel, Johanson, Murata, Panasonic
Not Installed
C31,C323
1000 pF, 3 kV, X7R, ±10%
Not Installed
D1,D24
Dual Diode, 300 V, 225 mA
Central Semiconductor
FB1,FB2
Ferrite Bead, BLM31A601S
Murata
Q1,Q3
A42, NPN, 300 V
OnSemiconductor, Fairchild, Zetex
OnSemiconductor, Fairchild, Zetex
Q2
A92, PNP, 300 V
Q45
BCP56, NPN, 60 V, 1/2 W
OnSemiconductor, Fairchild
RV1
Sidactor, 275 V, 100 A
Teccor, ST Microelectronics, Microsemi, TI
RV26
240 V, MOV
Not Installed
R22
402 Ω, 1/16 W, ±1%
R5
100 kΩ, 1/16 W, ±1%
R6
120 kΩ, 1/16 W, ±5%
R7,R8,R15,R16,R17,R198
4.87 kΩ, 1/4 W, ±1%
R9,R10
15 kΩ, 1/10 W, ±5%
R11
10 kΩ, 1/16 W, ±1%
R122
78.7 Ω, 1/16 W, ±1%
R132
215 Ω, 1/16 W, ±1%
R18
2.2 kΩ, 1/10 W, ±5%
R24
150 Ω, 1/16 W, ±5%
R25,R26
10 MΩ, 1/16 W, ±5%
U1
Si2400
Silicon Labs
U2
Si3015
Silicon Labs
Y1
4.9152 MHz, 20 pF, 50 ppm, 150 ESR
Not Installed
Z12
Zener Diode, 43 V, 1/2 W
Vishay, Motorola, Rohm
Notes:
1.
2.
3.
4.
5.
6.
7.
10
C2 was included in previous revisions of the data sheet. Replacing C2 with C4 improves longitudinal balance.
For FCC-only designs: C14, R12, and R13 are not required; R2 may be ±5%; with Z1 rated at 18 V, C5 may be rated at 16 V; also see note 7.
C30, C31, C32 may provide an additional improvement in emissions/immunity and/or voice performance, depending on design and layout. Population
option recommended. See "Emissions/Immunity‚" on page 62.
Several diode bridge configurations are acceptable (suppliers include General Semi., Diodes Inc.).
Q4 may require copper on board to meet 1/2 W power requirement. (Contact manufacturer for details.)
RV2 can be installed to improve performance from 2500 V to 3500 V for multiple longitudinal surges (240 V, MOV).
The R7, R8, R15, and R16, R17, R19 resistors may each be replaced with a single resistor of 1.62 kΩ, 3/4 W, ±1%. For FCC-only designs, 1.62 kΩ, 1/16
W, ±5% resistors may be used.
Rev. 0.95
Si2400
Analog Input/Output
Figure 4 illustrates an optional application circuit to support the analog output capability of the Si2400 for voice
monitoring purposes.
+5V
C2
R3
3
AOUT
6
2
4
C6
C4
5
U1
R1
C5
C3
R2
Speaker
Figure 4. Optional Connection to AOUT for a Monitoring Speaker
‘
Table 10. Component Values—Optional Connection to AOUT
Symbol
Value
C2, C3, C5
0.1 µF, 16 V, ±20%
C4
100 µF, 16 V, Elec. ±20%
C6
820 pF, 16 V, ±20%
R1
10 kΩ, 1/10 W, ±5%
R2
10 Ω, 1/10 W, ±5%
R3
47 kΩ, 1/10 W, ±5%
U1
LM386
Si2400
Analog Input
AIN/GPIO
1 Vrms
0.1 µF
Figure 5. Analog Input Circuit
Rev. 0.95
11
S i2 40 0
Functional Description
The Si2400 ISOmodem is a complete modem chipset
with integrated direct access arrangement (DAA) that
provides a programmable line interface to meet global
telephone line requirements. Available in two 16-pin
small outline packages, this solution includes a DSP data
pump, a modem controller, an analog front end (AFE), a
DAA, and an audio codec.
The modem, which accepts simple modem AT
commands, provides connect rates of up to 2400 bps,
full-duplex over the Public Switched Telephone Network
(PSTN) with V.42 hardware support through HDLC
framing. To minimize handshake times, the Si2400 can
implement a V.25-based fast connect feature. The
modem also supports the V.23 reversing protocol as well
as SIA and other alarm standard formats.
As well as supporting the modem signalling protocols, the
ISOmodem provides numerous additional features for
embedded modem applications. The Si2400 includes full
caller ID detection and decoding for the US, UK, and
Japanese caller ID formats. Both DTMF decoding and
generation are provided on chip as well. Call progress is
supported both at a high level through echoing result
codes and at a low level through user-programmable
biquad filters and parameters such as ring period, ring
on/off time, and dialing interdigit time.
This device is ideal for embedded modem applications
due to its small board space, low power consumption,
and global compliance. The Si2400 solution integrates a
silicon DAA using Silicon Laboratories’ proprietary
ISOcap™ technology. This highly integrated DAA can be
programmed to meet worldwide PTT specifications for
AC termination, DC termination, ringer impedance, and
ringer threshold. The DAA also can monitor line status for
parallel handset detection and for overcurrent conditions.
The Si2400 is designed so that it may be rapidly
assimilated into existing modem applications. The device
interfaces directly through a UART to either a
microcontroller or a standard RS-232 connection. This
simple interface allows for PC evaluation of the modem
immediately upon powerup via the AT commands across
a standard hyperterminal.
The chipset can be fully programmed to meet
international telephone line interface requirements with
full compliance to FCC, CTR21, JATE, and other countryspecific PTT specifications. In addition, the Si2400 has
been designed to meet the most stringent worldwide
requirements for out-of-band energy, billing-tone
immunity, lightning surges, and safety requirements.
The Si2400 solution needs only a few low-cost discrete
components to achieve global compliance. See Figure 3
on page 9 for a typical application circuit.
Table 11. Selectable Configurations
Modulation
Carrier
Frequency (Hz)
Data Rate
(bps)
Standard
Compliance
V.21
FSK
1080/1750
300
Full
V.22
DPSK
1200/2400
1200
Full
V.22bis (1200 fallback)
DPSK
1200/2400
1200
Full
V.22bis
QAM
1200/2400
2400
No retrain*
1300/2100
1200/75
1300/1700
600/75
Full; plus reversing
(Europe)
FSK
1170/2125
300
Full
Bell 212A
DPSK
1200/2400
1200
Full
Security
DTMF
—
40
Full
SIA—Pulse
Pulse
—
Low
Full
SIA Format
FSK
1170/2125
300 half-duplex
300 bps only
Configuration
V.23
FSK
V.23
Bell 103
*Note: The Si2400 only adjusts its baud rate for line conditions during the initialization of the call. Retraining to accommodate
changes in line conditions which occur during a call must be implemented by terminating the call and redialing.
12
Rev. 0.95
Si2400
Digital Interface
The Si2400 has an asynchronous serial port (UART)
that supports standard microcontroller interfaces. After
reset, the baud rate defaults to 2400 bps with the 8-bit
data format described below. Immediately after powerup, the device must be programmed using the primary
serial port because the secondary serial port is disabled
by default. The CLKOUT clock will be running with a
frequency of 9.8304 MHz.
The baud rate of the serial link is established by writing
S register SD (SE0.2:0). It may be set for 300, 1200,
2400, 9600, 19200, 228613, 245760, or 307200 bps.
Immediately after the ATSE0=xx string is sent, the user
must reprogram the host UART to match the selected
new baud rate. The higher baud rate settings (>230400)
can be used for transferring PCM data from the host to
the Si2400 for transmission of voice data over the
phone line or through the voice codec.
Table 12. Register S07 Examples: DTMF = 0,
HDEN = 0, BD = 0
data bits, and the line data format is 8 data bits (8N1),
then the MSB from the link will be dropped as the 9-bit
word is passed from the link side to the line side. In this
case, the dropped ninth bit can then be used as an
escape mechanism. However, if the link data format is 8
data bits and the line data format is 9 data bits, an MSB
equal to 0 will be added to the 8-bit word as it is passed
from the link side to the line side.
The Si2400 UART does not continuously check for stop
bits on the incoming digital data. Therefore, if the RXD
pin is not high, the TXD pin may transmit meaningless
characters to the host UART. This requires the host
UART to flush its receiver FIFO upon initialization.
Si2400
RXD
Si3015
UART
RJ11
TXD
Link
Line
Data Rate: SD (SE0.2:0)
Data Rate: S07
Data Format: ND (SE0.3)
Data Format: S15
Figure 6. Link and Line Data Formats
Modem Protocol
Register S07 Values
V.21
0x03
Command/Data Mode
Bell 103
0x01
V.22
0x02
Bell 212A
0x00
V.22bis
0x06
V.23 (75 tx, 1200 rx)
0x24
V.23 (1200 tx, 75 rx)
0x14
V.23 (75 tx, 600 rx)
0x20
Upon reset, the modem will be in command mode and
will accept AT-style commands. An outgoing modem
call can be made using the “ATDT#” (tone dial) or
“ATDP#” (pulse dial) command after the device is
configured. If the handshake is successful, the modem
will respond with the “c”, “d”, or “v” string and enter data
mode. (The byte following the “c”, “d”, or “v” will be the
first data byte.) At this point, AT-style commands are not
accepted. There are three methods which may be used
to return the Si2400 to command mode:
V.23 (600 tx, 75 rx)
0x10
!
Configurations and Data Rates
The Si2400 can be configured to any of the Bell and
CCITT operation modes. This device also supports SIA
and other security modes for the security industry.
Table 11 provides the modulation method, the carrier
frequencies, the data rate, the baud rate and the notes
on standard compliance for each modem configuration
of the Si2400. Table 12 shows example register settings
(SO7) for some of the modem configurations.
As shown in Figure 6, 8-bit and 9-bit data modes refer
to the link data format over the UART. Line data formats
are configured through registers S07 and S15. If the
number of bits specified by the link data format differs
from the number of bits specified by the line data
format, the MSBs will either be dropped or bit-stuffed,
as appropriate. For example, if the link data format is 9
!
!
Rev. 0.95
Use the ESC pin—To program the GPIO3 pin to
function as an ESCAPE input, set GPIO3
(SE2.5:4) = 3. In this setting, a positive edge
detected on this pin will return the modem to
command mode. The “ATO” string can be used to reenter data mode.
Use 9-bit data mode—If 9-bit data format with
escape is programmed, a 1 detected on bit 9 will
return the modem to command mode. (See Figure 2
on page 8.) This is enabled by setting ND (SE0.3) =
1 and NBE (S15.0) = 1. The “ATO” string can be
used to reenter data mode.
Use TIES—The time independent escape sequence
is a sequence of three escape characters ("+"
characters by default). Once these characters have
been recognized, the modem enters the Command
state without sending a confirming result code to the
terminal. The modem then starts an internal prompt
13
S i2 40 0
delay timer. From that point on if an AT<CR>
(attention) command is received before the timer
expires, the timer is stopped and the “O” response
code is sent to the terminal. This indicates that the
Si2400 is in command mode.
If any other data is received while the timer is
running, the timer is stopped, the device returns to
the online state, and the data received through the
UART RXD is sent to the other modem.
If the timer expires, a confirming “O” response code
is sent to the terminal indicating that the modem is in
command mode.
TIES can be enabled by writing register TED
(S14.5)=1. Both the escape character “+” and the
escape time-out period are programmable via
registers TEC (S0F) and TDT (S10), respectively.
Note: TIES is not the recommended escape solution for the
most robust designs. Any data strings that actually
contain the escape character three times in a row will
interrupt a data sequence erroneously.
Whether using an escape method or not, when the
carrier is lost, the modem will automatically return to
command mode and report “N”.
8-Bit Data Mode
This mode is asynchronous, full-duplex, and uses a
total of 10 bits (shown in Figure 2 on page 8). To
program 8-Bit Data mode, set ND (SE0.3) = 0. (Note
that 8-Bit Data mode is the default.) The 10 bits consist
of a start bit (logic 0), 8 data bits, and 1 stop bit (logic 1).
Data transmission from the Si2400 to the host takes
place on the TXD pin. It begins when the Si2400 lowers
TXD, placing the start bit on the pin. Data is then shifted
out onto the pin, LSB first. After 8 data bits, the stop bit
follows. All bits are shifted out at the rate determined by
the baud rate register.
Once the baud rate register SD (SE0.2:0) is written,
reception by the Si2400 may begin at any time. The
falling edge of a start bit will signal to the Si2400 that the
reception process has begun. Data should be shifted
onto RXD at the selected baud rate.
After the middle of the stop-bit time, the receiver will go
back to looking for a 1 to 0 transition on the RXD pin.
out onto the pin, LSB first. After 9 data bits, the stop bit
follows. All bits are shifted out at the rate determined by
the baud rate register.
Once the baud rate register SD (SE0.2:0) is written,
reception may begin at any time. The falling edge of a
start bit on the RXD pin will begin the reception process.
Data must be shifted in at the selected baud rate.
The ninth data bit may be used to indicate an escape by
setting NBE (S15.0) = 1. If so, this bit will normally be
set to 0 when the modem is online. To go offline into
command mode, set this bit to 1. The next frame will be
interpreted as a command. Data mode can be
reentered using the ATO command.
After the middle of the stop-bit time, the receiver will go
back to looking for a 1 to 0 transition on the RXD pin.
Flow Control
If a higher serial link line (UART) data rate is
programmed than the baud rate of the modem, flow
control is required to prevent loss of data to the
transmitter. No flow control is needed if the same baud
rate as modem rate is programmed. Note that in
compliance with the V.22bis algorithm, the V.22bis
(2400 baud) modem will connect at 1200 baud if it
cannot make a 2400 baud connection.
To control flow, the CTS pin is used. As shown in
Figure 2 on page 8, the CTS pin will normally be high,
and will be low whenever the modem is able to accept
new data. The CTS pin will go high again as soon as a
start bit is detected on the RXD pin and will remain high
until the modem is ready to accept another character.
Low Power Modes
The Si2400 has three low power modes. These are
described below:
!
!
9-Bit Data Mode
This mode uses a total of 11 bits in UART
communication. To program 9-Bit Data mode, set ND
(SE0.3) = 1. The 11 bits consist of one start bit (logic 0),
9 data bits, and 1 stop bit (logic 1, see Figure 2 on page
8). As in 8-Bit Data mode, the transmissions occur on
the TXD signal pin and receptions on the RXD pin.
!
Data transmission from the Si2400 to the host takes
place on the TXD pin. It begins when the Si2400 lowers
TXD, placing the start bit on the pin. Data is then shifted
14
Rev. 0.95
DSP Powerdown. The DSP processor can be
powered down by setting register PDDE (SEB.3) =1.
In this mode the serial interface still functions as
normal, and the modem will be able to detect ringing
and intrusion. No modem modes or tone detection
features will function.
Wake Up On Ring. By issuing the “z” command, the
Si2400 goes into a low power mode where both the
microcontroller and DSP are powered down. Only
incoming ringing or a total reset will power up the
chip again.
Total Powerdown. By writing registers PDN (SF1.6)
and PDL (SF1.5), the Si2400 will be put into a total
powerdown mode. In this mode, all logic is powered
down, including the crystal oscillator and clock-out
pin. Only a hardware reset can restart the Si2400.
Si2400
Global DAA Operation
The Si2400 chipset contains an integrated silicon direct
access arrangement (silicon DAA) that provides a
programmable line interface to meet international
telephone line interface requirements. Table 13 gives
the DAA register settings required to meet international
PTT standards. A detailed description of the registers in
Table 13 can be found in "Appendix A—DAA
Operation‚" on page 62.
Table 13. Country-Specific Register Settings
Register
Country
SF5
OHS
ACT
SF7
DCT
RZ
RT
LIM
SF6
VOL
FNM
Australia
1
1
2
0
0
0
0
0
Bulgaria
0
1
2
0
0
0
0
0
CTR211
0
1
3
0
0
1
0
0
Czech Republic
0
1
2
0
0
0
0
0
FCC
0
0
2
0
0
0
0
0
Hungary
0
0
2
0
0
0
0
0
Japan
0
0
1
0
0
0
0
0
Malaysia2
0
0
1
0
0
0
0
0
New Zealand
0
1
2
0
0
0
0
0
Philippines
0
0
1
0
0
0
0
1
Poland3
0
0
2
1
1
0
0
0
Singapore2
0
0
1
0
0
0
0
0
Slovakia
0
1
2
0
0
0
0
0
Slovenia
0
1
2
0
0
0
0
0
South Africa3
1
1
2
1
0
0
0
0
Korea3
0
0
1
1
0
0
0
0
South
Note:
1. CTR21 includes the following countries: Austria, Belgium, Cyprus, Denmark, Finland, France,
Germany, Greece, Iceland, Ireland, Israel, Italy, Liechtenstein, Luxembourg, Netherlands, Norway,
Portugal, Spain, Sweden, Switzerland, and the United Kingdom.
2. Supported for loop current ≥ 20mA.
3. The RZ register (SF5.1) should only be set for Poland, South Africa and South Korea if the ringer
impedance network (C15, R14, Z2, Z3) is not populated.
Parallel Phone Detection
The Si2400 has the ability to detect another phone that
is off hook on a shared line. This allows the ISOmodem
both the ability to avoid interrupting another call on a
shared line and to intelligently handle an interruption
when the Si2400 is using the line. An automatic
algorithm to detect parallel phone intrusion (defined as
an off-hook parallel handset) is provided by default.
On-Hook Intrusion Detection
The on-hook intrusion detection allows the user to avoid
interrupting another call on a shared line. To implement
the intrusion detection, the Si2400 uses a loop voltage
sense (register LVCS (SDB)). When on hook, LVCS
monitors the line voltage. (When off hook, it measures
current.) LVCS has a full scale of 70 V with an LSB of
2.25 V. The first code (0 → 1) is skewed such that a 0
indicates that the line voltage is < 3.0 V. The voltage
accuracy of LVCS is ±20%. The user can read these
bits directly when on hook through register LVCS.
The automatic on-hook detector algorithm can be
tripped by either an absolute level or by a voltage
differential by selecting ONHD (S13.3). If the absolute
detector is chosen, the Si2400 algorithm will detect an
intrusion if LVCS is less than the on-hook intrusion
Rev. 0.95
15
S i2 40 0
threshold, register AVL (S11.4:0). In other words, it is
determined that an intrusion has occurred if LVCS <
AVL.
lines with current-limiting specifications such as France.
For these lines, a differential detector is more
appropriate.
AVL defaults to 0x0D, or 30 V on powerup. The
absolute detector is the correct method to use for FCC
and most other countries. The absolute detector should
also be used to detect the presence (or absence) of a
line connection.
The differential detector method checks the status of the
line every 26.66 ms. The detector compares (LVCS (t –
0.02666) – LVCS (t)) to the differential threshold level
set in register DVL (S11.7:5). The default for DVL is
0x02 (5.25 V). If the threshold is exceeded (LVCS (t –
0.02666) – LVCS (t) > DVL), an intrusion is detected. If
(LVCS (t) – LVCS (t – 0.02666) > DVL), then the
intrusion is said to have terminated.
Under the condition of a very short line and a currentlimiting telephone off hook, the off-hook line voltage can
be as high as 40 V. The minimum on-hook voltage may
not be much greater. This condition can occur on phone
30
25
20
LVCS
BIT
15
10
5
0
0 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 48 51 54 57 60 63 66 69 72
Loop Voltage
Figure 7. Loop Voltage—LVCS Transfer Function
Off-Hook Intrusion Detection
When the Si2400 is off hook, it can detect another
phone going off hook by monitoring the DC loop current.
The loop current sense transfer function is shown in
Figure 8 with the upper curve representing CTR21
(current limiting) operation and the lower curve
representing all other modes. The overload points
indicate excessive current draw. The user can read
these bits directly through register LVCS (SDB). Note
that as in the line voltage sense, there is hysteresis
between codes (0.375 mA for CTR21 mode and
0.75 mA for ROW).
16
Rev. 0.95
100
Si2400
Overload
30
25
20
CTR21
LCS
BIT
15
10
5
0
0 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 48 51 54 57 60 63 66 69 72 75 78 81 84 87 90 93
140
Loop Current (mA)
Figure 8. Loop Current—LVCS Transfer Function
The off-hook algorithm can be chosen to use either a
differential current detector or an absolute current
detector via setting OFHD (S13.4).
Because of the extra code and host processing required
by the absolute current method, the differential current
method is chosen to be the default. This method uses
two techniques to detect an intrusion. The first
technique is described as follows:
If (LVCS (t – 400 ms) – LVCS (t)) > DCL, then an
intrusion is deemed to have taken place. If (LVCS (t) –
LVCS (t – 400 ms)) > DCL, then the intrusion is deemed
to have completed. Default DCL is 2.
The second technique takes advantage of the DC
holding circuit. If a parallel phone suddenly goes off
hook, the DC holding circuit will not react immediately,
therefore the loop current through the Si2400 will drop
briefly to zero. Thus, an intrusion is also reported when
LVCS = 0.
If the absolute detector is chosen, the Si2400 will detect
an intrusion under the condition that LVCS is less than
the off-hook intrusion threshold, register ACL (S12.4:0).
In other words, it is determined that an intrusion has
occurred if LVCS < ACL. ACL defaults to 3 (15.5 mA) on
powerup. Because the loop current can vary from
20 mA to 100 mA, depending on the line, a factory
preset threshold is not useful.
If the host wishes to use this absolute mode, the host
must measure the line current and then set the
threshold accordingly. A measurement of the loop
current is accomplished by going off-hook (issuing the
“ATDT;” command), reading LVCS after 50 ms, and
going back on hook using the “ATH” command. This
measured value of LVCS should be used to determine
the threshold register ACL. If this method is used, the
loop current should be measured on a periodic basis to
account for drift in line resistance.
The absolute current method is the most accurate, and
it is necessary to use this method in order to determine
if another phone goes off hook simultaneous with or
immediately (< 400 ms) after the Si2400 phone goes off
hook. It does, however, require processing by the host,
including periodic off-hook events to measure the loop
current.
If an intrusion event is detected while in command
mode, an “i” is echoed to the host; When it is terminated
an “I” is echoed. The host may also be notified of an
intrusion when in data mode through the ALERT pin by
setting GPIO4 (SE2.7:6) = 3. Upon intrusion, the
ALERT pin will go high, and the host may then read
register IND (S14.1) to confirm an intrusion.
The host may use the automatic intrusion detection
algorithm (the default) by monitoring the ALERT pin or
waiting for the character echoes. The host may also use
the LVCS, AVL, and DVL registers as a basis for a
custom algorithm. Note that LVCS only acts as a line
voltage sense when on hook. When off hook, it
becomes the line current sense register.
Rev. 0.95
17
S i2 40 0
Carrier Detect/Loss
The Si2400 can provide the functionality of a loss-ofcarrier pin similar to the CD pin functionality in an RS232 connection. If programmed as an ALERT, GPIO4
will go high in online mode when either parallel phone
intrusion or a loss-of-carrier is detected. When used in
this manner, the host detects a low-to-high transition on
GPIO4 (ALERT), escapes into command mode, and
reads register IND (S14.1). If high, IND indicates
intrusion. If low, IND indicates loss-of-carrier.
Overcurrent Protection
The Si2400 has built in protection to avoid damage to
the device due to overcurrent situations. An example
situation occurs when plugging the modem into a digital
PBX outlet and attempting to go off-hook. Digital PBX
systems vary, but many can provide a DC feed voltage
of up to 70 V and therefore have the ability to deliver
hundreds of milliamps of current into the DAA.
The Si2400 will always go off hook with the currentlimiting mode enabled. This allows no possibility of
damage for voltages up to about 48 V. However, at
higher voltages the 43 V Zener protection device will
begin to conduct and could be damaged if the power is
applied for too long.
The Si2400 will detect the value of the loop current at a
programmable time after going off-hook (default =
20 ms) via register OHT (S32). If the loop current is too
high, an “x” will be echoed back to the host to indicate a
fault condition. The host may then check register OD
(S14.3) to confirm an overcurrent condition and go back
on hook if necessary.
The user can optionally enable another protection
feature, the overcurrent protection, via register AOC
(S14.4). This protection feature can automatically detect
an overcurrent condition and put the Si2400 into a lower
drive mode, which is similar to the current-limiting mode
but has reduced hookswitch drive. This feature allows
the Si2400 to remain off-hook on a digital line for a
longer period of time without damage. If the Si2400
does not detect overcurrent after the time set by OCDT
(S32), then the correct line termination is applied. This
method of going off hook in current-limiting mode can
be disabled by clearing OFHE (S13.5).
Caller ID Decoding Operation
The Si2400 supports full caller ID detection and decode
for US Bellcore, UK, and Japanese standards. To use
the caller ID decoding feature, the following set-up is
necessary:
ID) or CIDB (S13.2) = 1 (Set modem to UK type caller ID)
or JID (S13.7) = 1 (Set modem to Japanese type caller ID)
3. Set baud rate either to 1200 bps without flow control or
greater than 1200 bps with flow control.
Bellcore Caller ID Operation
The Si2400 will detect the first ring burst signal and will
echo an “R” to the host. The device will then start
searching for the caller ID preamble sequence after the
appropriate time-out. When 50 continuous mark bits
have been detected, the “m” response will be echoed to
indicate that the mark has been detected and that caller
ID data will follow.
At this point the algorithm will look for the first start bit,
assemble the characters, and then transmit them out of
the UART as they are detected. When the caller ID
burst finishes, the carrier will be lost and the modem will
echo an “N” to indicate that the carrier is lost.
At this point the Si2400 will continue detecting ring
bursts and echoing “R” for each burst, and will
automatically answer after the correct number of rings.
UK Caller ID Operation
When the Si2400 detects a line reversal, it will echo an
“f” to the host. It will then start searching for the Idle
State Tone Alert Signal. When this signal has been
detected, the Si2400 will transmit an “a” to the host.
After the Idle State Tone Alert Signal is completed, the
Si2400 will apply the wetting pulse for the required
15 ms by quickly going off hook and on hook. From this
point on, the algorithm is identical to that of Bellcore in
that it will search for the channel seizure signal and the
marks before echoing an “m” and will then report the
decoded caller ID data.
Japan Caller ID Operation
After a polarity reversal and the first ring burst are
detected, the Si2400 is taken off hook. After 40 1s
(marks) have been detected, the Si2400 will search for
a start bit, echo an “m” for mark, and begin assembling
characters and transmitting them out through the serial
port. When the carrier is lost, the Si2400 immediately
hangs up and echoes “N”. Also, if no carrier is detected
for three seconds, the line hangs up and echoes “N”.
Force Caller ID Monitor
The Si2400 may be used to continuously monitor the
phone line for the caller ID mark signals. This can be
useful in systems that require detection of caller ID data
before the ring signal, voice mail indicator signals, and
Type II caller ID support. To force the Si2400 into caller
ID monitor mode, set CIDM (S0C.5).
1. Set ND (SEO.3) = 0 (Set modem to 8N1 configuration)
2. Set CIDU (S13.1) = 1(Set modem to Bellcore type caller
18
Rev. 0.95
Si2400
Tone Generation and Tone Detection
The Si2400 provides comprehensive and flexible tone
generation and detection. This includes all tones
needed to establish a circuit connection and to set up
and control a communication session. The tone
generation furnishes the DTMF tones for PSTN auto
dialing and the supervisory tones for call establishment.
The tone detection provides support for call progress
monitoring. The detector can also be user-programmed
to recognize up to 16 DTMF tones and two tone
detection bandpass filters.
DTMF tones may be detected and generated by using
the “ATA0” and “AT!0” commands described in the AT
command section. A description of the userprogrammable tones can be found in "Modem Result
Codes and Call Progress‚" on page 30.
PCM Data Mode
The Si2400 has the ability to bypass the modem
algorithm and send 14-bit PCM data, sampled at
9600 Hz, across the DAA. To use this mode, it is
necessary to set the serial link baud rate to at least
228613 bps (SE0), set PCM (S13.0) = 1, and set MCKR
(E1.7:6) = 0. The data format (Figure 9) requires that
the high byte be sent first containing bits D13–D7. The
LSB (B0) must equal zero. The low byte must be sent
next containing bits D6–D0; the LSB (B0) must equal
one. The receive data format is the same.
In PCM data mode, the line can be answered using the
“ATA;” command or a call can be originated using the
“ATDT#;” command. (The “;” is used to keep the modem
from leaving the command mode.) When PCM data
mode is enabled (set PCM (S13.0) = 1 and DRT
(SE4.5:4) = 0 (default)), data will immediately begin
streaming into and out of the serial port at a 9600 Hz*2
word rate. In this mode, the controller will not detect dial
tones or other call progress tones. If desired, the user
can monitor these tones using manual call progress
detection prior to entering the PCM data mode.
To exit the PCM data mode, an escape must be
performed either by pulsing the ESC pin or by using 9bit data mode and setting the ninth bit. (TIES cannot be
used in PCM data mode.) The escape command will
disable PCM streaming, and the controller will again
accept AT style commands.
Note: PCM data mode is the format that must also be used
when the Si2400 is configured to run as a voice codec
(DRT = 3).
PCM Receive Timing
8-Bit Data
High-Byte
TXD
B0
Start
Low-Byte
D7
D8
D9
D10
D11
D12
D13
B1
B2
B3
B4
B5
B6
B7
Stop
Start
B0
D0
D1
D2
D3
D4
D5
D6
B1
B2
B3
B4
B5
B6
B7
Stop
PCM Transmit Timing
8-Bit Data
High-Byte
RXD
D7
Start
B0
B1
Low-Byte
D8
D9
D10
D11
D12
D13
B2
B3
B4
B5
B6
B7
Stop
Start
B0
D0
D1
D2
D3
D4
D5
D6
B1
B2
B3
B4
B5
B6
B7
Stop
Note: Baud rates (programmed through register SE0) can be set to the following: 228613, 245760, and 307200.
Figure 9. PCM Timing
Rev. 0.95
19
S i2 40 0
Data Mode (DRT = 0)
Si2400
DSP
TX
A.
RX
RXD
TXD
Si3015
DSPOUT
RJ11
DSPIN
RJ11
AIN
AOUT
(Call Progress)
Voice Mode (DRT = 1)
Si2400
DSP
TX
B.
RX
RXD
TXD
Si3015
DSPOUT
RJ11
DSPIN
RJ11
AIN
AOUT
AIN
(Voice Out)
(Voice In)
Loopback Mode (DRT = 2)
Si2400
DSP
TX
C.
RX
RXD
TXD
DSPOUT
DSPIN
AOUT
AIN
Codec Mode (DRT = 3)
Si2400
DSP
TX
D.
RX
RXD
TXD
Si3015
RJ11
DSPOUT
DSPIN
AIN
AOUT
AIN
(Voice Out)
(Voice In)
Figure 10. Signal Routing
20
Rev. 0.95
Si2400
Analog Codec
V.23 Operation/V.23 Reversing
The Si2400 features an on-chip, voice quality codec.
The codec consists of a digital to analog converter
(DAC) and an analog to digital converter (ADC). The
sample rate for the codec is set to 9.6 kHz. When the
codec is powered on (set register APO (SE4.1)=1), the
output of the DAC is always present on the Si2400
AOUT pin. When the codec is powered off (APO = 0), a
PWM output is present on the AOUT pin instead. In
order to use the ADC, one of the four GPIO pins must
be selected as an analog input (AIN) by programming
the GPIO register (SE2).
The Si2400 supports full V.23 operation including the
V.23 reversing procedure. V.23 operation is enabled by
setting MF8 (S07) = xx10xx00 or xx01xx00. If V23R
(S07.5) = 1, then the Si2400 will transmit data at 75 bps
and receive data at either 600 or 1200 bps. If V23T
(S07.4) = 1, then the Si2400 will receive data at 75 bps
and transmit data at either 600 or 1200 bps. BAUD
(S07.2) is the 1200 or 600 bps indicator. BAUD = 1 will
enable the 1200/600 V.23 channel to run at 1200 bps
while BAUD = 0 will enable 600 bps operation.
Figure 10 shows the various signal routing modes for
the Si2400 voice codec, which are programmed through
register DRT (SE4.5:4). Figure 10A shows the data
routing for data mode. This is the default mode, which is
used for the modem data formats. In this configuration,
AOUT produces a mixed sum of the DSPOUT and
DSPIN signals and is typically used for call progress
monitoring through an external speaker. The relative
levels of the DSPOUT and DSPIN signals that are
output on the AOUT pin can be set through registers
ATL (SF4.1:0) and ARL (SF4.3:2).
Figure 10B shows the format for sending analog voice
across the DAA to the PSTN. AIN is routed directly
across the DAA to the telephone line. In this
configuration, AOUT produces a mixed sum of the
DSPOUT and DSPIN signals. The relative levels of the
DSPOUT and DSPIN signals that are output on the
AOUT pin can be set through registers ATL (SF4.1:0)
and ARL (SF4.3:2). Note that the DSP may process
these signals if it is not in PCM data mode. Thus, the
DSP may be used in this configuration, for example, to
decode DTMF tones. This is the mode used with the “!0”
and “A0” commands.
Figure 10C shows the loopback format, which can be
used for in-circuit testing. A detailed description of the
in-circuit test modes is described in the "Appendix A—
DAA Operation‚" on page 62.
Figure 10D shows the codec mode. This format is
useful, for example, in voice prompting, speaker
phones, or any systems involving digital signal
processing. In this mode, DSPOUT is routed to both the
AOUT pin and to the telephone line, and AIN is routed
directly to DSPIN.
Note that in all the DRT formats, the DSP must be in
PCM mode in order to pass DSPIN and DSPOUT
directly to and from TXD and RXD.
When a V.23 connection is successfully established, the
modem will respond with a “c” character if the
connection is made with the modem transmitting at
1200/600 bps and receiving at 75 bps. The modem will
respond with a “v” character if a V.23 connection is
established with the modem transmitting at 75 bps and
receiving at 1200/600 bps.
The Si2400 supports a V.23 turnaround procedure. This
allows a modem that is transmitting at 75 bps to initiate
a “turnaround” procedure so that it can begin
transmitting data at 1200/600 bps and receiving data at
75 bps. The modem is defined as being in V.23 master
mode if it is transmitting at 75 bps and it is defined as
being in slave mode if the modem is transmitting at
1200/600 bps. The following paragraphs give a detailed
description of the V.23 turnaround procedure.
Modem in master mode
To perform a direct turnaround once a modem
connection is established, the host goes into onlinecommand-mode by sending an escape command
(Escape pin activation, TIES, or ninth bit escape) to the
master modem. (Note that the host can initiate a
turnaround only if the Si2400 is the master.) The host
then sends the ATRO command to the Si2400 to initiate
a V.23 turnaround and to go back to the online (data)
mode.
The Si2400 will then change its carrier frequency (from
390 Hz to 1300 Hz), and wait for detecting a 390 Hz
carrier for 440 ms. If the modem detects more than
40 ms of a 390 Hz carrier into a time window of 440 ms,
it will echo the “c” response character. If the modem
does not detect more than 40 ms of a 390 Hz carrier
into a time window of 440 ms, it will hang up and echo
the “N” (no carrier) character as a response
Modem in slave mode
The Si2400 performs a reverse turnaround when it
detects a carrier drop longer than 20 ms. The Si2400
then reverses (it changes its carrier from 1300 Hz to
390 Hz) and waits to detect a 1300 Hz carrier for
220 ms. If the Si2400 detects more than 40 ms of a
Rev. 0.95
21
S i2 40 0
1300 Hz carrier in a time window of 220 ms, then it will
set the ALERT pin (GPIO4 must be configured as
ALERT) and the next character echoed by the Si2400
will be a “v”.
If the Si2400 does not detect more than 40 ms of the
1300 Hz carrier in a time window of 220 ms, then it
reverses again and waits to detect a 390 Hz carrier for
220 ms. Then, if the Si2400 detects more than 40 ms of
a 390 Hz carrier in a time window of 220 ms, it will set
the ALERT pin and the next character echoed by the
Si2400 will be a “c”.
At this point, if the Si2400 does not detect more than
40 ms of the 390 Hz carrier in a time window of 220 ms,
then it will hang up, set the ALERT pin, and the next
character echoed by the Si2400 will be an “N” (no
carrier).
Successful completion of a turnaround procedure in
either master or slave will automatically update V23T
(S07.4) and V23R (S07.5) to indicate the new status of
the V.23 connection.
In order to avoid using the ALERT pin, the host may
also be notified of the ALERT condition by using 9-bit
data mode. Setting NBE (S15.0) = 1 and 9BF (C.3) = 0
will configure the ninth bit on the Si2400 TXD path to
function exactly as the ALERT pin has been described.
V.42 HDLC Mode
The Si2400 supports V.42 through HDLC framing in
hardware in all modem data modes. Frame packing and
unpacking, including opening and closing flag
generation and detection, CRC computation and
checking, zero insertion and deletion, and modem data
transmission and reception are all performed by the
Si2400. V.42 error correction and data compression
must be performed by the host.
The digital link interface in this mode uses the same
UART interface (8-Bit Data and 9-Bit Data formats) as in
the asynchronous modes and the ninth data bit may be
used as an escape by setting NBE (S15.0) = 1. When
using HDLC in 9-Bit Data mode, if the ninth bit is not
used as an escape, it is ignored.
To use the HDLC feature on the Si2400, the host must
first enable HDLC operation by setting HDEN
(S07.7) = 1. Next, the host may initiate the call or
answer the call using either the “ATDT#”, the “ATA”
command, or the auto-answer mode. (The auto-answer
mode is implemented by setting register NR (S0) to a
non-zero value.) When the call is connected, a “c”, “d”,
or a “v” is echoed to the host controller. The host may
now send/receive data across the UART using either
the 8-Bit Data or 9-Bit Data formats with flow control.
At this point, the Si2400 will begin framing data into the
22
HDLC format. On the transmit side, if no data is
available from the host, the HDLC flag pattern is sent
repeatedly. When data is available, the Si2400
computes the CRC code throughout the frame and the
data is sent with the HDLC zero-bit insertion algorithm.
HDLC flow control operates in a similar manner to
normal asynchronous flow control across the UART and
is shown in Figure 11. In order to operate flow control
(using the CTS pin to indicate when the Si2400 is ready
to accept a character), a higher serial link baud rate
than the transmission line rate should be selected. The
method of transmitting HDLC frames is as follows:
1. After the call is connected, the host should begin sending
the frame data to the Si2400, using the CTS flow control to
ensure data synchronicity. A 1-deep character FIFO is
implemented in the Si2400 to ensure that data is always
available to transmit.
2. When the frame is complete, the host should simply stop
sending data to the Si2400. As shown in Figure 11B, since
the Si2400 does not yet recognize the end-of-frame, it will
expect an extra byte and assert CTS. If CTS is used to
cause a host interrupt, then this final interrupt should be
ignored by the host.
3. When the Si2400 is ready to send the next byte, if it has
not yet received any data from the host, it will recognize
this as an end-of-frame, raise CTS, calculate the final CRC
code, transmit the code, and begin transmitting stop flags.
4. After transmitting the first stop flag, the Si2400 will lower
CTS indicating that it is ready to receive the next frame
from the host. At this point the process repeats as in
step 1.
The method of receiving HDLC frames is as follows:
1. After the call is connected, the Si2400 searches for flag
data. Then, once the first non-flag word is detected, the
CRC is continuously computed, and the data is sent
across the UART (8-Bit Data or 9-Bit Data mode) to the
host after removing the HDLC zero-bit insertion. The baud
rate of the host must be at least as high as that of data
transmission. HDLC mode only works with 8-bit data
words; the ninth bit is used only for escape on RXD and
EOFR on TXD.
2. When the Si2400 detects the stop flag, it will send the last
data word in the frame as well as the two CRC bytes and
determine if the CRC checksum matches or not. Thus, the
last two bytes are not frame data, but are the CRC bytes,
which can be discarded by the host. If the checksum
matches, then the Si2400 echoes “G” (good). If the
checksum does not match, the Si2400 echoes “e” (error).
Additionally, if the Si2400 detects an abort (seven or more
contiguous ones), then it will echo an “A”.
When the “G”, “e”, or “A” (referred to as a frame result
word) is sent, the Si2400 raises the EOFR (end of frame
receive) pin (see Figure 10B). The GPIO1 pin must be
configured as EOFR by setting GPE (SE4.3) = 1. In
addition to using the EOFR pin to indicate that the byte is a
Rev. 0.95
Si2400
frame result word, if in 9-bit data mode (set NBE (S15.0) =
1), the ninth bit will be raised if the byte is a frame result
word. To program this mode, set 9BF (S0C.3) = 1 and ND
(SEO.3) = 1.
3. When the next frame of data is detected, EOFR is lowered
and the process repeats at step 1.
To summarize, the host will begin receiving data
asynchronously from the Si2400. When each byte is
received, the host should check the EOFR pin (or the
ninth bit). If the pin (or the ninth bit) is low, then the data
is valid frame data. If the pin (or the ninth bit) is high,
then the data is a frame result word.
Fast Connect
Clock Generation Subsystem
The Si2400 contains an on-chip clock generator. Using
a single master clock input, the Si2400 can generate all
modem sample rates necessary to support V.22bis,
V.22/Bell212A, and V.21/Bell103 standards as well as a
9.6 kHz rate for audio playback. Either a 4.9152 MHz
clock on XTALI or a 4.9152 MHz crystal across XTALI
and XTALO form the master clock for the Si2400. This
clock source is sent to an internal phase-locked loop
(PLL) which generates all necessary internal system
clocks. The PLL has a settling time of ~1 ms. Data on
RXD should not be sent to the device prior to settling of
the PLL.
In modem applications that require fast connection
times, it is possible to expedite the handshaking by
bypassing the answer tone. The No Answer Tone (NAT)
bit (S33.1) is intended to provide a method to decrease
the time needed to complete modem handshaking. If
the NAT bit is set, the Si2400 will bypass transmitting a
2100 Hz or 2225 Hz answer tone when receiving a call.
Instead, the modem will immediately begin the
handshaking sequence that normally follows answer
tone transmission. For example, when the modem is
configured as a V.22 answering modem, activating the
NAT bit will cause the modem to immediately transmit
unscrambled ones at 1200 bps after the modem
connects to the line. In addition, register UNL (S20) may
be used to set the length of time that the modem
transmits unscrambled ones. Setting UNL to a value
lower than the default may also shorten the answer
sequence.
A CLKOUT pin exists whereby a 78.6432 MHz/(N + 1)
clock is produced which may be used to clock a
microcontroller or other devices in the system. N may
be programmed via CLKD (SE1.4:0) to any value from 1
to 31, and N defaults to 7 on power-up. The clock may
be stopped by setting N = 0.
When the modem is set up to originate a call, setting the
NAT bit causes the modem to bypass the normal
answer tone search. Instead, the modem will send the
transmit sequence that normally occurs after receiving
the answer tone within 20 ms of the start of the answer
tone. For example, when the modem is configured as a
V.22 originating modem, activating the NAT bit will
cause the modem to start transmitting scrambled ones
at 1200 bps within 20 ms of the start of an answer tone.
Table 14. MCKR Configurations
The MCKR (microcontroller clock rate register SEI.7:6)
allows the user to control the microcontroller clock rate.
On powerup, the Si2400 UART baud rate is set to
2400 bps, given that the clock input is 4.9152 MHz. The
MCKR register conserves power via slower clocking of
the microcontroller for specific applications where
power conservation is required. Table 14 shows the
configurations for different values of MCKR.
Note that if MCKR = 0, then all of the serial interface link
rates will run at either half (MCKR = 1) or quarter
(MCKR = 2,3) speed.
When NAT=0, additional modem handshaking control
can be adjusted through registers TATL (S1E), ATTD
(S1F), UNL (S20), TSOD (S21), TSOL (S22), VDDL
(S23), VDDH (S24), SPTL (S25), VTSO (S26), VTSOL
(S27), VTSOH (S28), RSO (S2A), FCD (S2F), FCDH
(S30), RATL (S31), TASL (S34), and RSOL (S35).
These registers can be especially useful if the user has
control of both the originating and answer modems.
Rev. 0.95
MCKR
Modes Working
All modes
0
(9.8304 MHz)
1
All modes except
(4.9152 MHz) PCM streaming
and V22bis
2,3
Command modes
(2.4576 MHz) only
23
S i2 40 0
Host begins frame N
RXD
Host finished sending frame N
Start
Si2400 ready for byte 1 of frame N
Frame N
Host begins frame N + 1
Stop
Start
Frame N + 1
Si2400 detects
end of frame N
(CTS used as normal flow control)
Si2400 ready for byte 1
of frame N + 1
CTS
Note: Figure not to scale
A. Frame Transmit
TXD
Start
Receive Data
Stop
Start
CRC Byte 1
Stop
Start
CRC Byte 2
EOFR
(or bit 9)
B. Frame Receive
Figure 11. HDLC Timing
24
Rev. 0.95
Stop
Start
Frame Result Word
Stop
Si2400
AT Command Set
Table 15. AT Command Set Summary
The Si2400 supports a subset of the AT command set
as it is intended to be used with a dedicated
microcontroller instead of the complete set required for
general terminal entry applications.
Command
Command lines are typed to the modem when the
modem is in the Idle or Command state. Syntax for the
AT commands is case-sensitive.
DT#
Tone Dial Number
DP#
Pulse Dial Number
E
Local Echo On/Off
H
Hangup/Go On Line
I
Return Product Code + Chip Revision
M
Speaker Control Options
O
Return Online
RO
V.23 Reverse
A
A command line is defined as a string of characters
starting with the “A” and “T” characters and ending with
a special end-of-line character, <CR> (13 decimal).
Command lines may contain several commands, one
after another. If there are no characters between “AT”
and <CR>, the modem responds with “OK” after the
carriage return.
Command Line Execution
The characters in a command line are executed one at
a time. Unexpected command characters will be
ignored, but unexpected data characters may be
interpreted incorrectly.
S
After the modem has executed a command line, the
result code corresponding to the last command
executed is returned to the terminal or host. The
commands which warrant a response (e.g., “ATSR?”) or
“ATI” must be the last in the string and followed by a
<CR>. All other commands may be concatenated on a
single line. To echo command line characters, set the
Si2400 to echo mode using the E1 command.
All numeric arguments, including S-register numbers,
are in hexidecimal format and two digits must always be
entered.
< CR > End Of Line Character
This character is typed to end a command line. The
value of the <CR> character is 13, the ASCII carriage
return character. When the <CR> character is entered,
the modem executes the commands in the command
line. Commands which do not require a response are
executed immediately and do not need a <CR>.
Function
Answer Line Immediately with Modem
Read/Write S Registers
w##
Write S-Register in Binary
r#
Read S-Register in Binary
m#
Monitor S-Register in Binary
Z
Software Reset
z
Wakeup on Ring
AT Command Set Description
A
Answer
The “A” command makes the modem go off hook and
respond to an incoming call. This command is to be
executed after the Si2400 has indicated that a ring has
occurred. (The Si2400 will indicate an incoming ring by
echoing an “R”.)
This command is aborted if any other character is
transmitted to the Si2400 before the answer process is
completed.
Auto answer mode is entered by setting NR (S0) to a
nozero value. NR indicates the number of rings before
answering the line.
Upon answering, the modem communicates by
whatever protocol has been determined via the modem
control registers in S07.
If no transmit carrier signal is received from the calling
modem within the time specified in CDT (S39), the
modem hangs up and enters the idle state.
Rev. 0.95
25
S i2 40 0
D
Dial
M3
DT#
Tone Dial Number.
Speaker on after last digit dialed, off at carrier detect.
DP#
Pulse Dial Number.
O
The D commands make the modem dial a telephone
call according to the digits and dial modifiers in the dial
string following the commands. A maximum of 64 digits
is allowed. A DT command performs tone dialing, and a
DP command performs pulse dialing.
The “ATS07=40DT;” command can be used to go off
hook without dialing.
The dial string must contain only the digits “0–9”, “*”, “#”,
“A”, “B”, “C”, “D”, or the modifiers “;”, “/”, or “,”. Other
characters will be interpreted incorrectly. The modifier
“,” causes a two second delay in dialing. The modifier “/”
causes a 125 ms delay in dialing. The modifier “;”
returns the device to command mode after dialing and it
must be the last character.
Return to Online Mode
This command returns the modem to the online mode. It
is frequently used after an escape sequence to resume
communication with the remote modem.
RO
Turn-Around
This command initiates a V.23 “direct turnaround”
sequence and returns online.
S
S Register Control
SR=N
Write an S register. This command writes the value “N”
to the S-register specified by “R”. “R” is a hexidecimal
number, and “N” must also be a hexadecimal number
from 00–FF. This command does not wait for a carriage
return <CR> before taking effect.
If any character is received by the Si2400 between the
ATDT#<CR> (or ATDP#<CR>) command and when the
connection is made (“c” is echoed), the extra character
is interpreted as an abort, and the Si2400 returns to
command mode, ready to accept AT commands.
Note: Two digits must always be entered for both “R” and “N”.
If the modem does not have to dial (i.e., “ATDT<CR>” or
“ATDP<CR>” with no dial string), the Si2400 assumes
the call was manually established and attempts to make
a connection.
Note: Two digits must always be entered for R.
SR?
Read an S register. This command causes the Si2400
to echo the value of the S-register specified by R in hex
format. R must be a hexidecimal number.
w##
Write S Register in Binary
Tells the Si2400 whether or not to echo characters sent
from the terminal when the modem is accepting AT
commands.
This command writes a register in binary format. The
first byte following the “w” is the address in binary
format and the second byte is the data in binary format.
This is a more rapid method to write registers than the
“SR=N” command and is recommended for use by a
host microcontroller.
EO
r#
Does not echo characters sent from the terminal.
This command reads a register in binary format. The
byte following the “r” is the address in binary format.
The modem will echo the contents of this register in
binary format. This is a more rapid method to read
registers than the “SR?” command and is
recommended for use by a host microcontroller.
E
Command Mode Echo
E1
Echo characters sent from the terminal.
H
Hangup
Hang up and go into command mode (go offline).
I
Chip Identification
This command causes the modem to echo the chip
revision for the Si2400 device.
M
Speaker On/Off Options
These options are used to control AOUT for use with a
call progress monitor speaker.
M0
Speaker always off.
M1
Notes: When using this command, the modem result
codes should be disabled by setting MRCD (S14.7) = 1.
This ensures that the host will not confuse a result code
with data being read.
w## and r# are not required to be on separate lines (i.e.,
no <CR> between them). Also, the result of an r# is
returned immediately without waiting for a <CR> at the
end of the AT command line.
Once a <CR> is encountered, “AT” is again required to
begin the next “AT” command.
Speaker on until carrier established.
M2
Speaker always on.
26
Read S Register in Binary
Rev. 0.95
Si2400
m#
Monitor S Register in Binary
This command monitors a register in binary format. The
byte following the “m” is the address in binary format.
The Si2400 constantly transmits the contents of the
register at the set baud rate until a new byte is
transmitted to the device. The new byte is ignored and
viewed as a stop command. The modem result codes
should be disabled (as described above in r#) before
using this command.
Z
Software Reset
The “Z” command causes a software reset to occur in
the device whereby all registers will return to their
default power up value. If other commands follow on the
same line, another AT is needed after the “Z” (e.g.,
ATZATS07=06<CR>).
z
Wakeup on Ring
The Si2400 enters a low-power mode wherein the DSP
and microcontroller are powered down. The serial
interface also stops functioning. In this mode, only the
line-side chip (Si3015) and the ISOcap communication
link function. An incoming ring signal causes the Si2400
to power up and echo a “w”. Without a ring signal, the
host must perform a hardware reset to power up the
Si2400.
Table 16. AT Command Set Extensions
for Alarm Industry
Extended AT Commands for the Alarm
Industry
In addition to the AT command set used to make a data
modem connection, the Si2400 also supports a
complete set of commands required for making calls
and connections in security industry systems. These
commands are summarized in Table 16.
A0
After answering, connect AIN analog signal to phone
line transmit signal and output the phone line receive
signal to the AOUT pin (See Figure 10B). Also, this
mode monitors for DTMF received digits and the user
defined frequencies. A digit is reported by echoing the
character received. Transmission of any data to the
Si2400 UART will cause the modem to go into
command mode.
Once in command mode, the modem may be
disconnected with the “ATH” command, or DTMF tones
may be generated by using the “ATDT#” command. (In
this case, “ATDT#” does not initiate a new call because
the Si2400 has not been hung up and is still online.)
Online mode can be resumed by issuing the “ATO”
command. (User-defined frequencies are reported as X
and Y for user defined frequencies 1 and 2,
respectively. To enable user-defined frequencies, set
UDF (S14.6) = 1.) Setting the user-defined frequencies
requires DSP low-level control.
A1
Function
Answer line and follow the "SIA Format" protocol for
Alarm System Communications at 300 bps (see !2).
A0
Answer and switch to DTMF monitor mode
!0
A1
Answer and switch to “SIA Format”
!0
Dial and switch to DTMF monitor mode
!1
Dial and switch to DTMF security mode
After dialing the number, go into DTMF monitor mode
(no modem connection). After dialing is complete, the
connection is exactly the same as for the “AO”
command.
!2
Dial and switch to “SIA Format”
Note: When using “!” commands, the first instance of “!” must
be on the same line as the “ATDT#” or “ATDP#”.
!3
Dial and switch to GDC—P1
!1
!4
Dial and switch to GDC—P2
Dial number and follow the DTMF security protocol. “#”
is the DTMF message to transmit.
!5
Dial and switch to GDC—P3
!6
Dial and switch to GDC—P4
X1
SIA half-duplex mode search
X2
SIA half-duplex return online as
transmitter
X3
SIA half-duplex return online as receiver
Command
The modem dials the phone number and then echoes
“r”, “b”, and “c” as appropriate. “c” echoes only after the
Si2400 detects the Handshake Tone. After a 250 ms
wait, the modem sends the DTMF tones. Next, the
modem searches for a Kissoff tone. If the Kissoff tone is
detected, the Si2400 echoes a “K” and the controller
may begin sending the next message. The message
should end with a <CR>.
Rev. 0.95
27
S i2 40 0
In order to send another message, the Si2400 must
begin to receive the next message from the host within
250 ms of echoing the “K”. The next message must be
proceeded by the “!” character. To resend the same
message, the host can transmit a “~”. After the Si2400
echoes the “K”, any character other than “!” or “~”
indicates an abort to the Si2400, and it will exit into
command mode, echoing an “O”. Note that this aborts
the sending process, but the modem remains off-hook.
Multiple messages may be sent in this manner. If the
Kissoff tone is not detected by the Si2400 within 1.25
seconds, it will echo with a “^”. In this case, the host
may transmit a “~” after the “^” and the message will be
resent.
Notes:
1. While the DTMF message is being sent, the Si2400 is not
in command mode. No characters should be transmitted to
the Si2400 during this time. The only exceptions are the “!”
and “~” characters, which have special meanings as
described above. If any other character is transmitted it is
ignored, the message is aborted, and the Si2400 returns to
command mode expecting AT commands.
2. The escape pin or ninth bit has no effect in security modes.
3. A second kissoff tone detector has been added that will
return the character “k” if a kissoff tone longer than the
value stored in KTL (S36) is detected (default = 1 second).
4. Setting (S0C.0) will cause a “.” character to be echoed
when the DTMF tone is turned on and the "/" character to
be echoed when the tone is turned off. This can help give
the controller an indication of the progress of the message
transmission.
5. This command may also be used without being proceeded
by the ATDT command. Thus, transmitting an “AT!1#” will
immediately send the “#” message without dialing.
!2
After dialing the number, follow the "SIA Format"
protocol for Alarm System Communications. The
signaling speed is set to 300 bps. The modem dials the
phone number and then echoes “r” and “b” as
appropriate. Once the handshake tone is detected, the
speed synchronization signal is sent, and an
acknowledge “c” is echoed. The modem is then put
online in half-duplex FSK. After the “c” is received by
the host, the host can then send the first SIA block.
Once the host has transmitted the SIA block, it can
monitor for the acknowledge tone by completing the
following sequence:
1. The Si2400 should be put in command mode by
issuing an escape (pulsing the escape pin).
2. At this point the “ATX1” command may be issued.
This causes the modem to turn off the transmitter and
begin monitoring for the acknowledgment tones.
28
3. If a positive (negative) acknowledgment is detected a
“P” (“N”) is displayed once the tone has been detected
for 400 ms.
4. The modem is still in command mode at this point. It
can be put back online as a transmitter by issuing the
“ATX2” command, or put online as a receiver by issuing
the “ATX3” command.
This sequence can be repeated to send long messages.
Notes:
1. If tonal acknowledgment is not used, and the host wants to
reverse the line, it can issue an escape and immediately
program “ATX2” or “ATX3” to reverse the data direction.
2. Ninth bit escape does not operate in security modes.
This command may also be used without being
proceeded by the “ATDT” command. Thus, transmitting
an “AT!2#” will immediately send the “#” message
without dialing.
!3
Dial the phone number and transmit the message
according to the Generic SIA pulse format P1 protocol.
After the handshake tone, the Si2400 responds with “c”
and then transmits the message with the correct timing.
When the message is sent, the device waits for the
kissoff tone. If a kissoff tone is detected, the modem
echoes a “K” and enters command mode. If no kissoff
tone is detected and the Inter-Round time (S36) timeout
has expired, then the Si2400 echoes a “^”.
To resend the message, the host can respond with “~”
after receiving the “^”. If not, the host can respond with
“O” to enter command mode. In these modes, setting
(SC.0) causes a “.” to be echoed when the tone is
turned on and a “/” to be echoed when the tone is turned
off. This can help give the controller an indication of how
the message is progressing.
Note: Max number digits = 64 including phone number and !3
command
!4
This command is identical to S3 except pulse format P2
is used.
!5
This command is identical to S3 except pulse format P3
is used.
!6
This command is identical to S3 except pulse format P4
is used.
Note: Commands “AT!3#”, “AT!4#”, “AT!5#”, and “AT!6#”
may also be used without being preceded by the
“ATDT” command. For example, transmitting an “AT!6#”
will immediately send the # message without dialing.
Rev. 0.95
Si2400
X1
X3
Search for positive and negative acknowledge tones in
SIA half-duplex 300 bps mode. The Si2400 will respond
with “P” when a positive acknowledge is detected and
“N” when a negative acknowledge is detected.
Return to online mode in SIA half-duplex mode as
receiver.
X2
Return to online mode in SIA half-duplex mode as
transmitter.
Table 17. Si2400 Global Ringer and Busy Tone Cadence Settings
Country
RTON
RTOF
RTOD
BTON
BTOF
BTOD
Australia
7
3
1
37
37
4
Austria
18
93
10
30
30
3
Belgium
18
56
6
50
50
5
Brazil
18
75
8
25
25
3
China
18
75
8
35
35
4
Denmark
14
140
15
25
25
3
Finland
14
93
10
30
30
3
France
28
65
7
50
50
5
Germany
18
75
8
50
50
5
Great Britain
6
3
2
37
37
4
Greece
18
75
8
30
30
3
Hong Kong, New Zealand
7
4
1
50
50
5
India
7
3
1
75
75
8
Ireland
7
4
1
50
50
5
Italy, Netherlands, Norway, Thailand,
Switzerland, Israel
18
75
8
50
50
5
Japan, Korea
18
37
4
50
50
5
Malaysia
8
4
1
35
65
7
Mexico
18
75
8
25
25
3
Portugal
18
93
10
50
50
5
Singapore
7
4
1
75
75
8
Spain
28
56
6
20
20
2
Sweden
18
93
10
25
25
3
Taiwan
18
37
4
50
50
5
U.S., Canada (default)
38
75
7
50
50
15
Rev. 0.95
29
S i2 40 0
Modem Result Codes and Call Progress
Table 18. Modem Result Codes (Continued)
Table 18 shows the modem result codes which can be
used in call progress monitoring. All result codes are
only a single character in order to speed up the
communication and ease processing by the host.
x
Overcurrent State Detected After an
Off-Hook Event
^
Kissoff tone detection required
,
Dialing Complete
Table 18. Modem Result Codes
Automatic Call Progress Detection
Command
30
Function
The Si2400 has the ability to detect dial, busy and
ringback tones automatically. The following is a
description of the algorithms that have been
implemented for these three tones.
a
British Telecom Caller ID Idle Tone
Alert Detected
b
Busy Tone Detected
c
Connect
d
Connect 1200 bps (when programmed as V.22bis modem)
f
Hookswitch Flash or Battery Reversal Detected
H
Modem Automatically Hanging Up in
Japan Caller ID Mode
I
On-Hook Intrusion Completed
(phone back on hook)
i
On-Hook Intrusion Detected (phone
off-hook on the line)
K
SIA Contact ID Kissoff Tone
Detected
L
Phone Line Detected
l
No Phone Line Detected
1. Dial Tone. The dial tone detector looks for a dial tone after
going off hook and before dialing is initiated. This can be
bypassed by enabling blind dialing (set BD (S07.6) =1).
After going off hook, the Si2400 waits the number of
seconds in DW (S01) before searching for the dial tone.
In order for a dial tone to be detected, it must be present
for the length of time programmed in DTT (SIC). Once the
dial tone is detected, dialing will commence. If a dial tone
is not detected for the time programmed in CW (S02), the
Si2400 will hangup and echo an “N” to the user.
2. Busy / Ringback Tone. After dialing has completed, the
Si2400 monitors for Busy/Ringback and modem answer
tones. The busy and ringback tone detectors both use the
call progress energy detector.
Si2400 register settings for global cadences for busy and
ringback tones are listed in Table 17, including the default
settings for registers BTON (S16), BTOF (S17), BTOD
(S18), RTON (S19), RTOF (S1A), and RTOD (S1B).
Manual Call Progress Detection
Because other call progress tones beyond those
described above may exist, the Si2400 supports manual
call progress. This requires the host to read and write
the low-level DSP registers and may require realtime
control by the host. Manual call progress may be
required for detection of application-specific ringback,
dial tone, and busy signals.
m
Caller ID Mark Signal Detected
N
No Carrier Detected
n
No Dial tone (time-out set by CW
(S02))
Note: Manual call progress requires DSP low-level control.
The section on DSP low level control should be read
before attempting manual call progress detection.
O
Modem OK Response
R
Incoming Ring Signal Detected
r
Ringback Tone Detected
S
Resending SIA Contact ID Data
To use this mode, the automatic modem responses
should be disabled by setting MRCD (S14.7) = 1. The
call progress biquad filters can be programmed to have
a custom desired frequency response and detection
level (as described in “Modem Result Codes and Call
Progress” ).
t
Dial Tone
v
Connect 75 bps (V.23 only)
Four dedicated user-defined frequency detectors can
be programmed to search for individual tones. The four
detectors have center frequencies which can be set
through registers UDFD1–4 (see Table 20). TDET (SE5
(SE8 = 0x02) Read Only Definition) can be monitored,
Rev. 0.95
Si2400
along with TONE, to detect energy at these userdefined frequencies. The trip-threshold for UDFD1–4 is
–30 dBm.
By issuing the “ATDT;” command, the modem will go off
hook and return to command mode. The user can then
put the DSP into call progress monitoring by first setting
SE8 = 0x02. Next, set SE5 = 0x00 so no tones are
transmitted, and set SE6 to the appropriate code,
depending on which types of tones are to be detected.
Table 19. DTMF
DTMF
Code
Keyboard
Equivalent
0
At this point, users may program their own algorithm to
monitor the detected tones. If the host wishes to dial, it
should do so by blind dialing, setting the dial timeout
PW (SO1) to 0 seconds, and issuing an “ATDT#;”
command. This will immediately dial and return to
command mode.
Once the host has detected an answer tone using
manual call progress, the host should immediately
execute the “ATA” command in order to make a
connection. This will cause the Si2400 to search for the
modem answer tone and begin the correct connect
sequence.
In manual call progress, the DSP can be programmed
to detect specific tones. The result of the detection is
reported into SE5 (SE8 = 0x2) as explained above. The
output is priority encoded such that if multiple tones are
detected, the one with the highest priority whose
detection is also enabled is reported (see SE5
(SE8=02) Read Only).
Tones
Low
High
0
941
1336
1
1
697
1209
2
2
697
1336
3
3
697
1477
4
4
770
1209
5
5
770
1336
6
6
770
1477
7
7
852
1209
8
8
852
1336
9
9
852
1477
10
D
941
1633
In manual call progress, the DSP can be programmed
to generate specific tones (see TONC register SE5
(SE8 = 02) Write Only). For example, setting TONC = 6
will generate the user-defined tone as indicated by
UFRQ in Table 20 with an amplitude of TGNL.
11
*
941
1209
12
#
941
1477
13
A
697
1633
Table 19 shows the mappings of Si2400 DTMF values,
keyboard equivalents, and the related dual tones.
14
B
770
1633
15
C
852
1633
Rev. 0.95
31
S i2 40 0
Low Level DSP Control
Although not necessary for most applications, the DSP
low-level control functions have been made available for
users with very specific requirements who must control
the DSP more directly.
DSP word requires two writes from the host. When
SE8 = 1, SE5 represents the 8 LSBs of the word, and
SE6.5:0 represents the 6 MSBs. Tables 20 and 21
define the DSP registers.
DSP Registers
Note: SE8=0 and SE8=1 must be used only when the
modem is not already “online.”
The DSP registers may be accessed through the
Si2400 microcontroller. S-registers SE5, SE6, SE7, and
SE8 are used to read and write the DSP registers. The
definition of SE5 and SE6 both depend on the value of
SE8 and whether they are being read or written. Both of
these conditions are given in the register definitions for
SE5 and SE6 (see "S Registers‚" on page 35).
Example1: The user would like to program call
progress filter coefficient A2_k0 (0x15) to be 309
(0x135).
When SE8 = 0 or 1, SE5 and SE6 are defined directly
as the address (SE8 = 0) and data (SE8 = 1) of the
internal DSP registers. The address field is 8 bits wide.
As shown in Tables 20 and 21, DSP address values
range from 0x02 to 0x0B and from 0x10 to 0x23. To
write an address, set SE8 = 0 and then write the DSP
address to register SE5 and SE6. Writing any other
DSP addresses than those shown in Tables 20 and 21
may cause unpredictable behavior by the DSP. The
DSP data field is 14 bits wide. Thus, writing a single
Host Command:
ATSE8=00SE6=00SE5=15SE8=01SE6=01SE5=35SE8=00
In the command above, ATSE8=00 sets up registers
SE5 and SE6 as DSP address registers. SE6=00 sets
the high bits of the address, and SE5=15 sets the low
bits. SE8=01 sets up registers SE5 and SE6 as DSP
data registers for the previously written DSP address
(0x15). SE6=01 sets the high 6 bits of the 14-bit data
word, and SE5=35 sets the low 8 bits of the 14-bit data
word.
When SE8=2, depending on whether the host is reading
or writing, SE5 and SE6 are as defined in the S-register
tables.
Table 20. Low-Level DSP Parameters
DSP Register
Address
32
Name
Description
Function
Default
0x02
XMTL
DAA modem full scale transmit level,
default = –10 dBm
Level = 20log10 (XTML/4096)
–10 dBm
4096
0x03
DTML
DTMF high tone transmit level,
default = –5 dBm
Level = 20log10 (DTML/5157)
–5 dBm
5157
0x04
DTMT
DTMF twist ratio (low/high), default =
–2 dBm
Level = 20log10 (DTMT/3277)
–2 dB
3277
0x05
UFRQ
User-defined transmit tone frequency.
See register SE5 (SE8=0x02 (Write
Only))
f = (9600/512) UFRQ (Hz)
0x06
CPDL
Call progress detect level (see
Figure 12), default = –34 dBm
Level = 20log10 (4096/CPDL)
–34 dBm
4096
0x07
UDFD1
User-defined frequency detector 1.
Center frequency for detector 1.
UDFD1 = 8192 cos (2π f/9600)
4987
0x08
UDFD2
User-defined frequency detector 2.
Center frequency for detector 2.
UDFD2 = 8192 cos (2π f/9600)
536
0x09
UDFD3
User-defined frequency detector 3.
Center frequency for detector 3.
UDFD3 = 8192 cos (2π f/9600)
4987
Rev. 0.95
91
Si2400
Table 20. Low-Level DSP Parameters (Continued)
DSP Register
Address
Name
0x0A
UDFD4
0x0B
TGNL
Description
Function
Default
User-defined frequency detector 4.
Center frequency for detector 4.
UDFD4 = 8192 cos (2π f/9600)
536
Tone generation level associated with
TONC (SE5 (SE8 = 0x02) Write Only
Definition), default = –10 dBm
Level = 20log10 (TGNL/2896)
– 10 dBm
2896
Call Progress Filters
The programmable call progress filters coefficients are
located in DSP address locations 10H through 23H.
There are two independent 4th order filters A and B,
each consisting of two biquads, for a total of 20
coefficients. Coefficients are 14 bits (–8192 to 8191)
and are interpreted as, for example, b0 = value/4096,
thus giving a floating point value of approximately –2.0
to 2.0. Output of each biquad is calculated as
Table 21. Call Progress Filters
DSP Register
Address
Coefficient
Default
0x10
A1_k0
1024
0x11
A1_b1
–2046
0x12
A1_b2
1024
0x13
A1_a1
7737
0x14
A1_a2
–3801
The output of the filters is input to an energy detector
and then compared to a fixed threshold with hysteresis
(DSP register CPDL). Defaults shown are a bandpass
filter from 80–650 Hz (–3 dB). These registers are
located in the DSP and thus must be written in the same
manner described in "Modem Result Codes and Call
Progress‚" on page 30.
0x15
A2_k0
309
0x16
A2_b1
10
0x17
A2_b2
309
0x18
A2_a1
7109
The filters may be arranged in either parallel or cascade
through register CPCD (SE6.6 (SE8=0x02)), and the
output of filter B may be squared by selecting CPSQ
(SE6.7 (SE8=0x02)). Figure 12 shows a block diagram
of the call progress filter structure.
0x19
A2_a2
–3565
0x1A
B1_k0
1024
0x1B
B1_b1
–2046
0x1C
B1_b2
1024
0x1D
B1_a1
7737
0x1E
B1_a2
–3801
0x1F
B2_k0
309
0x20
B2_b1
10
0x21
B2_b2
309
0x22
B2_a1
7109
0x23
B2_a2
–3565
w[n] = k0 * x[n] + a1 * w[n – 1] + a2 * w[n – 2]
y[n] = w[n] + b1 * w[n – 1] + b2 * w[n – 2].
Rev. 0.95
33
S i2 40 0
0
CPCD
1
Filter Input
Filter B
1
Energy
Detect
0
y = x2
B
0
CPCD 1
A
0 CPSQ
Filter A
Max
(A,B)
A
Hysteresis
B A > B? TDET
Energy
Detect
20log10(4096/CPDL) –34 dBm
Figure 12. Programmable Call Progress Filter Architecture
34
Rev. 0.95
Si2400
S Registers
Note: Any register not documented here is reserved and should not be written.
Table 22. S-Register Summary
Register
Name
0
NR
Number of rings before answer; 0 suppresses auto answer.
0x00
1
DW
Number of seconds modem waits before dialing (maximum of 109 seconds).
0x03
2
CW
Number of seconds modem waits for a dial tone before hang-up added to
time specified by DW (maximum of 109 seconds).
0x14
3
CLW
Duration that the modem waits (53.33 ms units) after loss of carrier before
hanging up.
0x0E
4
TD
Both duration and spacing (5/3 ms units) of DTMF dialed tones.
0x30
5
OFFPD
Duration of off-hook time (5/3 ms units) for pulse dialing.
0x18
6
ONPD
Duration of on-hook time (5/3 ms units) for pulse dialing.
0x24
7
MF1
8
MNRP
9
MXRP
A
ROT
B
C
MNRO
MF2
Function
Reset
This is a bit mapped register.1
0000_0001
2
Minimum ring period (5/3 ms units).
Maximum ring period (5/3 ms units).
0x0A
2
0x28
Ringer off time (53.333 ms units).2
0x4B
2
Minimum ringer off time (10 ms units).
0x28
1
0000_0000
This is a bit mapped register.
2
0x16
D
RPE
Ringer off time allowed error (53.333 ms units).
E
DIT
Pulse dialing Interdigit time (10 ms units added to a minimum time of 64 ms).
0x46
F
TEC
TIES escape character. Default = +.
0x2B
10
TDT
TIES delay time (256 * 5/3 ms units).
0x07
1
11
ONHI
This is a bit mapped register.
0100_1101
12
OFHI
This is a bit mapped register.1
0100_0011
13
MF14
This is a bit mapped register.1
0001_0000
MF15
1
0000_0000
1
1000_0100
14
This is a bit mapped register.
15
MLC
This is a bit mapped register.
16
BTON
Busy tone on. Time that the busy tone must be on (10 ms units) for busy tone
detector.
0x32
17
BTOF
Busy tone off. Time that the busy tone must be off (10 ms units) for busy tone
detector.
0x32
18
BTOD
Busy tone delta. Detector Time Delta (10 ms). A busy tone is detected to be
valid if (BTON – BTOD < on time < BTON + BTOD) and (BTOF – BTOD < off
time < BTOF + BTOD).
0x0F
19
RTON
Ringback tone on. Time that the ringback tone must be on (53.333 ms units)
for ringback tone detector.
0x26
1A
RTOF
Ringback tone off. Time that the ringback tone must be off (53.333 ms units)
for ringback tone detector.
0x4B
Rev. 0.95
35
S i2 40 0
Table 22. S-Register Summary (Continued)
1B
RTOD
Detector time delta (53.333 ms units). A ringback tone is determined to be
valid if (RTON – RTOD < on time < RTON + RTOD) and (RTOF – RTOD < off
time < RTOF + RTOD).
0x07
1C
DTT
Dial tone time. The time that the dial tone must be valid before being detected
(10 ms units).
0x0A
1D
36
DTMFD DTMF detect time. The time that a DTMF tone must be valid before being
detected (10 ms units).
0x03
1E
TATL
Transmit answer tone length. Answer tone length in seconds when answering
a call (3 seconds units).
0x03
1F
ATTD
Answer tone to transmit delay. Delay between answer tone end and transmit
data start (5/3 ms units).
0x2D
20
UNL
Unscrambled ones length. Minimum length of time required for detection of
unscrambled binary ones during V.22 handshaking by a calling modem
(5/3 ms units).
0x5D
21
TSOD
Transmit scrambled ones delay. Time between unscrambled binary one
detection and scrambled binary one transmission by a call mode V.22 modem
(5/3 ms units added to a minimum time of 426.66 ms).
0x09
22
TSOL
Transmit scrambled ones length. Length of time scrambled ones are sent by
a call mode V.22 modem (5/3 ms units).
0xA2
23
VDDL
V.22X data delay low. Delay between handshake complete and data connection for a V.22X call mode modem (5/3 ms units added to the time specified
by VDDH).
0xCB
24
VDDH
V.22X data delay high. Delay between handshake complete and data connection for a V.22X call mode modem (256 * 5/3 ms units added to the time
specified by VDDL).
0x08
25
SPTL
S1 pattern time length. Amount of time the unscrambled S1 pattern is sent by
a call mode V.22bis modem (5/3 ms units).
0x3C
26
VTSO
V.22bis 1200 bps scrambled ones length. Minimum length of time for transmission of 1200 bps scrambled binary ones by a call mode V.22bis modem
after the end of pattern S1 detection (5/3 ms units added to a minimum time
of 426.66 ms).
0x0C
27
VTSOL
V.22bis 2400 bps scrambled ones length low. Minimum length of time for
transmission of 2400 bps scrambled binary ones by a call mode V.22bis
modem (5/3 ms units added to the time specified by VTSOH).
0x78
28
VTSOH
V.22bis 2400 bps scrambled ones length high. Minimum length of time for
transmission of 2400 bps scrambled binary ones by a call mode V.22bis
modem (256 * 5/3 ms units added to the time specified by VTSOL).
0x08
2A
RSO
Receive scrambled ones V.22bis (2400 bps) length.
Minimum length of time required for detection of scrambled binary ones during V.22bis handshaking by the answering modem after S1 pattern conclusion (5/3 ms units).
0xD2
2B
DTL
V.23 direct turnaround carrier length. Minimum length of time that a master
mode V.23 modem must detect carrier when searching for a direct turnaround
sequence (5/3 ms units).
0x18
Rev. 0.95
Si2400
Table 22. S-Register Summary (Continued)
2C
DTTO
V.23 direct turnaround timeout. Length of time that the modem searches for a
direct turnaround carrier (5/3 ms units added to a minimum time of
426.66 ms).
0x08
2D
SDL
V.23 slave carrier detect loss. Minimum length of time that a slave mode
V.23 modem must lose carrier before searching for a reverse turnaround
sequence (5/3 ms units).
0x0C
2E
RTCT
V.23 reverse turnaround carrier timeout. Amount of time a slave mode V.23
modem will search for carriers during potential reverse turnaround sequences
(5/3 ms units).
0x84
2F
FCD
FSK connection delay low. Amount of time delay added between end of
answer tone handshake and actual modem connection for FSK modem
connections (5/3 ms units).
0x3C
30
FCDH
FSK connection delay high. Amount of time delay added between end of
answer tone handshake and actual modem connection for FSK modem connections (256*5/3 ms units).
0x00
31
RATL
Receive answer tone length. Minimum length of time required for detection
of a CCITT answer tone (5/3 ms units).
0x3C
32
OCDT
The time after going off hook when the loop current sense bits are checked
for overcurrent status (5/3 ms units).
0x0C
33
MDMO
This is a bit mapped register.1
34
TASL
Answer tone length when answering a call (5/3 ms units). This register is only
used if TATL (1E) has a value of zero.
0x5A
35
RSOL
Receive scrambled ones V.22 length (5/3 ms units). Minimum length of time
that an originating V.22 (1200 bps) modem must detect 1200 bps scrambled
ones during a V.22 handshake.
0xA2
36
SKDTL
Second kissoff tone detector length. The security modes A1 and !1 will echo a
“k” if a kissoff tone longer than the value stored in SKDTL is detected
(10 ms units).
0x64
37
CDR
Carrier detect return. Minimum length of time that a carrier must return and be
detected in order to be recognized after a carrier loss is detected
(5/3 ms units).
0x20
38
IRT
Interround time. Time between messages in security pulse modes
(53 ms units).
0x38
39
CDT
Carrier detect timeout. Amount of time modem will wait for carrier detect
before aborting call (1 second units).
0x3C
3A
ATD
Delay between going off-hook and answer tone generation when in answer
mode (53.33 ms units).
0x29
3B
RP
Minimum number of consecutive ring pulses per ring burst.
0x03
DB
LVCS
Loop voltage (on-hook)/loop current (off-hook) register
0x00
E0
E1
CF1
CLK1
0000_0000
1
0000_0010
1
0100_0111
1
This is a bit mapped register.
This is a bit mapped register.
E2
GPIO
This is a bit mapped register.
0000_0000
E3
GPD
This is a bit mapped register.1
0000_0000
Rev. 0.95
37
S i2 40 0
Table 22. S-Register Summary (Continued)
E4
CF5
E5
DADL
E5
DDL
This is a bit mapped register.1
0000_0000
(SE8 = 0x00) Write only definition. DSP register address lower bits [7:0].1
(SE8 = 0x01) Write only definition. DSP data word lower bits [7:0].
1
1
0x00
0x00
E5
DSP1
(SE8 = 0x02) Read only definition. This is a bit mapped register.
0x00
E5
DSP2
(SE8 = 0x02) Write only definition. This is a bit mapped register.1
0x00
E6
DADH
(SE8 = 0x00) Write only definition. DSP register address upper bits [15:8]
0x00
E6
DDH
(SE8 = 0x01) Write only definition. DSP data word upper bits [13:8]
0x00
1
E6
DSP3
E7
DSPR3
This is a bit mapped register.1
E8
DSPR4
Set the mode to define E5 and E6.
E9
RTH
Timer high. High bits of the realtime timer (see register EA).
EA
RTL
Timer low. Low bits of the realtime timer. The timer has an LSB of 5/3 ms, with
maximum time count at 109 seconds. RTL should always be read first, with
RTH read second.
EB
TPD
This is a bit mapped register.1
0000_0000
F0
DAA0
This is a bit mapped register.1
0000_0000
DAA1
1
0001_1100
1
F1
(SE8 = 0x02) Write only definition. This is a bit mapped register.
This is a bit mapped register.
0x00
0000_0000
0x00
F2
DAA2
This is a bit mapped register.
0000_0000
F4
DAA4
This is a bit mapped register.1
0000_1111
DAA5
1
0000_1000
1
0000_0000
1
F5
F6
DAA6
This is a bit mapped register.
This is a bit mapped register.
F7
DAA7
This is a bit mapped register.
0001_0000
F8
DAA8
This is a bit mapped register.1
xxxx_1100
DAA9
1
0000_0000
F9
This is a bit mapped register.
Notes:
1. These registers are explained in detail in the following section.
2. The ring detector will only detect ringing if the ring burst on/off times meet the settings in MNRP, MXRP, MNRU, ROT,
and REP.
38
Rev. 0.95
Si2400
Register 7. Modem Functions 1
Bit
D7
D6
D5
Name HDEN
BD
V23
Type
R/W
R/W
R/W
D4
D3
MODM DTMF
R/W
R/W
D2
D1
BAUD CCITT
R/W
R/W
D0
FSK
R/W
Reset settings = 0000_0001
Bit
Name
7
HDEN
Function
HDLC Framing.
0 = Disable
1 = Enable
6
BD
Blind Dialing.
0 = Disable
1 = Enable (Blind dialing occurs immediately after “ATDT#” command.)
5
V23R
V.23 Receive.
V.23 75 bps send/600 (BAUD = 0) or 1200 (BAUD = 1) bps receive
0 = Disable
1 = Enable
4
V23T
V.23 Transmit.
V.23 600 (BAUD = 0) or 1200 (BAUD = 1) bps send/75 bps receive
0 = Disable
1 = Enable
3
DTMF
DTMF Tone Detector.
0 = Disable
1 = Enable
2
BAUD
2400/1200 Baud Select.
2400/1200 baud select (V23R = 0 and V23T = 0)
0 = 1200
1 = 2400
600/1200 baud select (V23R = 1 and V23T = 1)
0 = 600
1 = 1200
1
CCITT
CCITT/Bell Mode.
0 = Bell
1 = CCITT
0
FSK
300 bps FSK.
0 = Disable
1 = Enable
Rev. 0.95
39
S i2 40 0
Register C. Modem Functions 2
Bit
D7
D6
D5
D4
D3
D2
D1
D0
Name
CIDM
9BF
BDL
MLB
MCH
Type
R/W
R/W
R/W
R/W
R/W
Reset settings = 0000_0000
Bit
Name
Function
7:6
Reserved
Read returns zero.
5
CIDM
Caller ID Monitor.
Causes the Si2400 to search for the caller ID Channel Seizure Signal (alternating 1/0
pattern) continuously.
0 = Disable (default)
1 = Enable
4
Reserved
3
9BF
Read returns zero.
Ninth Bit Function.
Only valid if the ninth bit escape is set (S15.0).
0 = Ninth bit equivalent to ALERT.
1 = Ninth bit equivalent to HDLC EOFR.
2
BDL
Blind Dialing.
Enables blind dialing after register CW dial timeout (S02) expires.
1
MLB
Modem Loopback.
Swaps frequency bands in modem algorithm to do a loopback in a test mode.
0
MCH
Miscellaneous Characters.
Enables “.” and “/” character echoing to indicate tone on and tone off for security mode
and the SIA pulse modes.
Register 11. On-Hook Intrusion
Bit
D7
D6
D5
D4
D3
D2
Name
DVL
AVL
Type
R/W
R/W
D1
D0
Reset settings = 0100_1101
Bit
Name
7:5
DVL
Function
Differential Voltage Level.
Differential voltage level to detect intrusion event.
4:0
AVL
Absolute Voltage Level.
Absolute voltage level to detect intrusion event.
40
Rev. 0.95
Si2400
Register 12. Off-Hook Intrusion
Bit
D7
D6
D5
D4
D3
D2
Name
DCL
ACL
Type
R/W
R/W
D1
D0
Reset settings = 0100_0011
Bit
Name
7:5
DCL
Function
Differential Current Level.
Differential current level to detect intrusion event.
4:0
ACL
Absolute Current Level.
Absolute current level to detect intrusion event.
Rev. 0.95
41
S i2 40 0
Register 13. Modem Functions 3
Bit
D7
D6
D5
D4
Name
JID
BTID
OFHE
OFHD
Type
R/W
R/W
R/W
R/W
D3
D2
D1
ONHD CIDB CIDU
R/W
R/W
R/W
D0
PCM
R/W
Reset settings = 0001_0000
Bit
Name
7
JID
Function
Japan Caller ID.
0 = Disable
1 = Enable
6
BTID
BT Caller ID Wetting Pulse D.
0 = Enable
1 = Disable
5
OFHE
Enable Off Hook.
Enable off hook in current limit mode for overcurrent protection.
0 = Disable
1 = Enable
4
OFHD
Off Hook Intrusion Detect Method.
0 = Absolute
1 = Differential
3
ONHD
On Hook Intrusion Detect Method.
0 = Absolute
1 = Differential
2
CIDB
British Telecom Caller ID Decode.
0 = Disable
1 = Enable
1
CIDU
BellCore Caller ID Decode.
0 = Disable
1 = Enable
0
PCM
PCM Data Mode.
Baud rate must be ≥ 228613, and flow control must be used.
0 = Disable
1 = Enable
42
Rev. 0.95
Si2400
Register 14. Modem Functions 4
Bit
D7
D6
D5
D4
D3
D2
D1
D0
Name MRCD
UDF
TEO
AOC
OD
NLD
IND
RD
Type
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset settings = 0000_0000
Bit
Name
7
MRCD
6
UDF
Function
Disable Modem Result Codes.
User Defined Frequency.
Enables user defined frequency detectors in A0 and !0 modes.
5
TEO
TIES Escape Operation.
Enables TIES escape operation.
4
AOC
AutoOverCurrent Protection.
Enables AutoOverCurrent protection.
3
OD
Overcurrent Detected.
Sticky.
2
NLD
No Phone Line Detected.
1
IND
Intrusion Detected.
0
RD
Ring Detected.
Rev. 0.95
43
S i2 40 0
Register 15. Modem Link Control
Bit
D7
D6
D5
Name ATPRE VCTE FHGE
Type
R/W
R/W
D4
D3
EGHE
STB
BDA
NBE
R/W
R/W
R/W
R/W
R/W
D2
D1
D0
Reset settings = 1000_0100
Bit
Name
Function
7
ATPRE
6
VCTE
V.25 Calling Tone Enable.
5
FHGE
550 Hz Guardtone Enable.
4
EHGE
1800 Hz Guardtone Enable.
3
STB
Answer Tone Phase Reversal Enable.
Stop Bits.
0 = 1 stop bit
1 = 2 stop bits
2:1
BDA
Bit Data.
00 = 6 bit data
01 = 7 bit data
10 = 8 bit data
11 = 9 bit data
0
NBE
Ninth Bit Enable.
Enable ninth bit as Escape and ninth bit function (register C).
44
Rev. 0.95
Si2400
Register 33. Modem Override
Bit
D7
D6
D5
Name
DON
Type
R/W
D4
D3
D2
D1
D0
DOF
NAT
TSAC
R/W
R/W
R/W
Reset settings = 1000_0000
Bit
Name
7
Reserved
6
DON
Function
Read returns one.
On-Hook Intrusion Detect.
0 = Enable (default)
1 = Disable
5
DOF
Off-Hook Intrusion Detect.
0 = Enable (default)
1 = Disable
4:2
Reserved
Read returns zero.
1
NAT
No Answer Tone.
Enable no answer tone fast handshake.
0
TSAC
Transmit Scrambler Active.
Force transmit scrambler active once connected.
Rev. 0.95
45
S i2 40 0
Register E0. Chip Functions 1
Bit
D7
D6
Name
D5
D4
ICTS
D3
D2
ND
D1
D0
SD
Type
Reset settings = 0010_0010
Bit
Name
7:6
Reserved
5
ICTS
Function
Read returns zero.
Invert CTS pin.
0 = Inverted (CTS)
1 = Normal (CTS)
4
Reserved
Read returns zero.
3
ND
0 = 8N1
1 = 9N1 (hardware UART only)
2:0
SD
Serial Dividers.
0 = 300 bps serial link
1 = 1200 bps serial link
2 = 2400 bps serial link
3 = 9600 bps serial link
4 = 19200 bps serial link
5 = 228613 bps serial link (0.8% error to 230400 bps)
6 = 245760 bps serial link
7 = 307200 bps serial link
46
Rev. 0.95
Si2400
Register E1. Chip Functions 2
Bit
Name
D7
D6
D5
D4
MCKR
D3
D2
D1
D0
CLKD
Type
Reset settings = 0100_0111
Bit
Name
7:6
MCKR
Function
Microcontroller Clock Rate.
0 = Fastest 9.8304 MHz (default)
1 = 4.9152 MHz
2 = 2.4576 MHz
3 = Reserved
Note: MCKR must be set to 0 when the UART baud rate is set to 228613 or greater
(SD = 5, 6, or 7).
5
Reserved
Read returns zero.
4:0
CLKD
CLK_OUT Divider.
0 = Disable CLK_OUT pin
CLK_OUT = 78.6432/(CLKD + 1) MHz
Rev. 0.95
47
S i2 40 0
Register E2. Chip Functions 3
Bit
D7
D6
D5
D4
D3
D2
D1
D0
Name
GPIO4
GPIO3
GPIO2
GPIO1
Type
R/W
R/W
R/W
R/W
Reset settings = 0000_0000
Bit
Name
7:6
GPIO4
Function
GPIO4.
0 = Digital input
1 = Digital output (relay drive)
2 = Analog input
3 = ALERT function (digital output)
5:4
GPIO3
GPIO3.
0 = Digital input
1 = Digital output (relay drive)
2 = Analog input
3 = ESCAPE function (digital input)
3:2
GPIO2*
GPIO2.
0 = Digital input
1 = Digital output (relay drive)
2 = Analog input
3 = Reserved
1:0
GPIO1*
GPIO1.
0 = Digital input
1 = Digital output (relay drive)
2 = Analog input
3 = Reserved
*Note: To be used as analog input or GPIO pins; GPE (SE4.3) and TRSP (SE4.0) must both equal zero.
48
Rev. 0.95
Si2400
Register E3. Chip Functions 4
Bit
D7
D6
Name
AING
Type
R/W
D5
D4
D3
D2
D1
D0
GPD4 GPD3 GPD2 GPD1
R/W
R/W
R/W
R/W
Reset settings = 0000_0000
Bit
Name
7:6
AING
Function
AIN Gain Bits.
00 = 0 dB
01 = 6 dB
10 = 2.5 dB
11 = 12 dB
5:4
Reserved
Read returns zero.
3
GPD4
GPIO4 Data.
2
GPD3
GPIO3 Data.
1
GPD2
GPIO2 Data.
0
GPD1
GPIO1 Data.
Rev. 0.95
49
S i2 40 0
Register E4. Chip Functions 5
Bit
D7
D6
D5
D4
D3
D2
D1
D0
Name NBCK SBCK
DRT
GPE
APO
TRSP
Type
R/W
R/W
R/W
R/W
R
R
Reset settings = 0000_0000
Bit
Name
Function
7
NBCK
9600 Baud Clock (Read Only).
6
SBCK
600 Baud Clock (Read Only).
5:4
DRT
Data Routing
0 = Data mode, DSP output transmitted to line, line received to DSP input
1 = Voice mode, selected AIN transmitted to line, line received to AOUT
2 = Loopback mode, RXD through microcontroller (DSP) to TXD. AIN looped to AOUT.
3 = Codec mode, data from DSPOUT to AOUT, selected AIN to DSPIN
3
GPE*
GPIO1 Enable.
Enable GPIO1 to be HDLC end-of-frame flag.
2
Reserved
1
APO
Read returns zero.
Analog Power On.
Power on analog ADC and DAC.
0
TRSP*
TXD2/RXD2 Serial Port.
Enable TXD2/RXD2 serial port so that TXD2 is GPIO1 and RXD2 is GPIO2.
*Note: GPE and TRSP are mutually exclusive. Only one can be set at any one time, and they override the settings in registers
GPIO2 and GPIO1. Once TXD2 and RXD2 are enabled through TRSP = 1, the primary serial port TXD and RXD no
longer function and pins TXD2 and RXD2 control the Si2400. This feature allows a second microcontroller to control
the Si2400.
50
Rev. 0.95
Si2400
Register E5. (SE8 = 0x02) Read Only Definition
Bit
D7
D6
D5
D4
D3
Name DDAV TDET
Type
R
R
D2
D1
D0
TONE
R
Reset settings = 0000_0000
Bit
Name
Function
7
DDAV
DSP Data Available.
6
TDET
Tone Detected.
Indicates a TONE (any of type 0–25 below) has been detected.
0 = Not detected
1 = Detected
5
Reserved
4:0
TONE
Read returns zero.
Tone Type Detected.
When TDET goes high, TONE indicates which tone has been detected from the following:
TONE
Tone Type
Priority
0–15
DTMF 0–15 (DTMFE = 1) See Table 19 on page 31
1
16
Answer tone detected 2100 Hz (ANSE = 1)
2
17
Bell 103 answer tone detected 2225 Hz (ANSE = 1)
2
18
V.23 forward channel mark 1300 Hz (V23E = 1)
3
19
V.23 backward channel mark 390 Hz (V23E = 1)
3
20
User defined frequency 1 (USEN1 = 1)
4
21
User defined frequency 2 (USEN1 = 1)
4
22
Call progress filter A detected
6
23
User defined frequency 3 (USEN2 = 1)
5
24
User defined frequency 4 (USEN2 = 1)
5
25
Call progress filter B detected
6
Rev. 0.95
51
S i2 40 0
Register E5. (SE8 = 0x02) Write Only Definition
Bit
D7
D6
D5
D4
D3
D2
D1
D0
Name
DTM
TONC
Type
W
W
Reset settings = 0000_0000
Bit
Name
7
6:3
Reserved
DTM
2:0
TONC
Function
Read returns zero.
DTMF tone (0–15) to transmit when selected by TONC (TONC = 1). See Table 19 on
page 31
Tone
Tone Type
0
1
2
3
4
5
6
Mute
DTMF
2225 Hz Bell mode answer tone with phase reversal
2100 Hz CCITT mode answer tone with phase reversal
2225 Hz Bell mode answer tone without phase reversal
2100 Hz CCITT mode answer tone without phase reversal
User-defined programmable frequency tone (UFRQ)
(see Table 20 on page 32, default = 1700 Hz)
1300 Hz V.25 calling tone
7
Register E6. (SE8 = 0x02) Write Only Definition
Bit
D7
D6
Name
CPSQ
Type
W
D5
D4
D3
D2
D1
D0
CPCA
USEN2
USEN1
V23E
ANSE
DTMFE
W
W
W
W
W
W
Reset settings = 0000_0000
Bit
Name
7
CPSQ
6
CPCD
5
4
3
2
1
0
Reserved
USEN2
USEN1
V23E
ANSE
DTMFE
52
Function
1 = Enables a squaring function on the output of filter B before the input is input to A
(cascade mode only).
0 = Call progress filter B output is input into call progress filter A. Output from filter A is
used in the detector.
1 = Cascade disabled. Two independent fourth order filters available (A and B). The
largest output of the two is used in the detector.
Enables the reporting of user defined frequency tones 3 and 4 through TONE.
Enables the reporting of user defined frequency tones 1 and 2.
Enables the reporting of V.23 tones, 390 Hz and 1300 Hz.
Enables the reporting of answer tones.
Enables the reporting of DTMF tones.
Rev. 0.95
Si2400
Register E7. DSPR3 Write Only
Bit
D7
D6
D5
D4
D3
D2
D1
D0
Name
MLO
REIN
REEN
Type
W
W
W
Reset settings = 0000_0000
Bit
Name
Function
7:3
Reserved
Read returns zero.
2
MLO
Modem Loopback.
1
REIN
Receiver Equalizer Inhibit.
0
REEN
Receiver Equalizer Enable.
Register EB. Timer and Power Down
Bit
D7
D6
D5
D4
D3
D2
Name
CWTI
DWRC
PDDE
Type
R/W
R/W
R/W
D1
D0
Reset settings = 0000_0000
Bit
Name
Function
7:6
Reserved
5
CWTI
Clear Watchdog Timer.
4
DWRC
Disable Watchdog Reset Circuit.
3
PDDE
Power Down DSP Engine.
Read returns zero.
0 = Power on
1 = Power down
2:0
Reserved
Read returns zero.
Rev. 0.95
53
S i2 40 0
Register F0. DAA Low Level Functions 0
Bit
D7
D6
D5
D4
D3
D2
Name
D1
D0
LM
OFHK
Type
Reset settings = 0000_0000
Bit
Name
7:2
Reserved
1
LM
0
OFHK
Function
Read returns zero.
Hook Control/Status.1,2,3
OFHK
0
0
0
0
1
1
1
1
LM
0
0
1
1
0
0
1
1
LM0
0
1
0
1
0
1
0
1
Line Status Mode
On hook
On hook with LVCS as voltage monitor
On hook line monitor mode (Si3014 compatible)
On hook line monitor mode (Si3015 compatible)
Off hook with LVCS as loop current monitor
Reserved
Reserved
Reserved
Notes:
1. See Register F7 on page 60 for LM0.
2. Under normal operation, the Si2400 internal microcontroller will automatically set these bits appropriately.
3. Force on hook supports caller ID type 2.
54
Rev. 0.95
Si2400
Register F1. DAA Low Level Functions 1
Bit
D7
D6
D5
D4
D3
D2
D1
D0
Name
BTE
PDN
PDL
CPE
RXE
HBE
AL
DL
Type
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset settings = 0001_1100
Bit
Name
7
BTE
Function
Billing Tone Enable.
When the Si3015 detects a billing tone, BTD is set.
0 = Disable
1 = Enable
6
PDN
Power Down.
0 = Normal operation.
1 = Powers down the Si2400.
5
PDL
Power Down Line-Side Chip.
0 = Normal operation. Program the clock generator before clearing this bit.
1 = Places the Si3015 in lower power mode.
4
CPE
Charge Pump Enable.
0 = Charge pump off.
1 = Charge pump on.
3
RXE
Receive Path Enable.
0 = Disable
1 = Enable
2
HBE
Hybrid Transmit Path Connect.
1 = Connects transmit path in hybrid
1
AL
Analog Loopback.
1 = Enables external analog loopback mode.
0 = Analog loopback mode disabled.
0
DL
Isolation Digital Loopback.
1 = Enables digital loopback mode across isolation barrier. The line side must be
enabled prior to setting this mode.
0 = Digital loopback across isolation barrier disabled.
Rev. 0.95
55
S i2 40 0
Register F2. DAA Low Level Functions 2
Bit
D7
D6
D5
D4
D3
D2
D1
D0
Name
LCS
FDT
RDT
RDTN
RDTP
Type
R
R
R/W
R
R
Reset settings = 0000_0000
Bit
Name
7:4
LCS
Function
Loop Current Sense.
Four-bit value returning the loop current in 6-mA increments.
0 = Loop current < 0.4 mA.
1111 = Loop current > 155 mA. See “Loop Current Monitor” section.
3
FDT
Frame Detect.
1 = Indicates ISOcap frame lock has been established.
0 = Indicates ISOcap frame lock has not been established.
2
RDT
Ring Detect.
1 = Indicates a ring is occurring.
0 = Reset either 4.5–9 seconds after last positive ring is detected or when the system
executes an off-hook.
1
RDTN
Ring Detect Signal Negative.
When set, a negative ring signal is occurring.
0
RDTP
Ring Detect Signal Positive.
When set, a positive ring signal is occurring.
56
Rev. 0.95
Si2400
Register F4. DAA Low Level Functions 4
Bit
D7
D6
D5
D4
D3
D2
D1
D0
Name
SQLH
ARG
ARL
ATL
Type
R/W
R/W
R/W
R/W
Reset settings = 0000_1111
Bit
Name
7
SQLH
Function
Ring Squelch.
If the host implements a manual ring detect (bypassing the Si2400 micro), this bit must
be set, then cleared following a polarity reversal detection. Used to quickly recover offset
on RNG1/2 pins after polarity reversal.
0 = Normal
1 = Squelch
6:4
3:2
ARG
ARL
Analog Receive Gain.
Off-Hook
On-Hook
000 = 0 dB gain
001 = 3 dB gain
010 = 6 dB gain
011 = 9 dB gain
1xx = 12 dB gain
000 = 7 dB
001 = 6 dB
010 = 4.8 dB
011 = 3.5 dB
1xx = 2.0 dB
AOUT Receive—Path Level
DAA receive path signal AOUT gain.
0 = 0 dB
1 = –6 dB
2 = –12 dB*
3 = Mute
1:0
ATL
AOUT Transmit—Path Level
DAA transmit path signal AOUT gain.
0 = –18 dB
1 = –24 dB
2 = –30 dB*
3 = Mute
*Note: If ARL = 2 and ATL = 2, AOUT is muted.
Rev. 0.95
57
S i2 40 0
Register F5. DAA Low Level Functions 5
Bit
D7
D6
D5
D4
Name
FULLS
DCTO
OHS
ACT
D3
D2
DCT
D1
D0
RZ
RT
Type
Reset settings = 0000_1000
Bit
Name
7
FULLS
Function
Full Scale.
0 = Default
1 = Modem codec fullscale > 3.2 dBm
6
DCTO
DC Termination Off.
Presents an 800 Ω impedance to the line.
0 = Enable DC termination
1 = Disable
5
OHS
On-Hook Speed.
0 = The Si2400 will execute a fast on-hook.
1 = The Si2400 will execute a slow, controlled on-hook.
4
ACT
AC Termination.
0 = Real impedance
1 = Complex impedance
3:2
DCT
DC Termination Voltage.
00 = Norway mode (maximum transmit level = –5 dBm)
01 = Japan mode (maximum transmit level = –3 dBm)
10 = USA mode (maximum transmit level = –1 dBm) (default)
11 = TBR21/France current limit mode (maximum transmit level = –1 dBm)
1
RZ
Ringer Impedance Decrease.
Decreases ringer impedance.
0 = Disable (Rest of World)
1 = Enable (Korea, Poland, South Africa)
0
RT
Ringer Threshold.
0 = 11–21 Vrms threshold
1 = 21–31 Vrms threshold
58
Rev. 0.95
Si2400
Register F6. DAA Low Level Functions 6
Bit
D7
D6
D5
Name
MCAL
Type
R/W
D4
D3
D2
D1
D0
ACAL
FJM
VDD3_TWK
VOL
FNM
R/W
R/W
R/W
R/W
R/W
Reset settings = 0000_0000
Bit
Name
7
Reserved
6
MCAL
Function
Read returns zero.
Manual Calibration Request.
0 = Normal
1 = Immediately calibrate
Note: Must disable autocalibration (ACAL) before using manual calibration.
5
ACAL
Automatic Calibration Disable.
0 = Enable (default)
1 = Disable
4
Reserved
3
FJM
Read returns zero.
Force Japan DC Termination.
0 = Normal mode
1 = Force Japan DC termination
2
VDD3_TWK
VDD3 Voltage Tweak.
0 = Nominal
1 = Forces VDD3 = 2.1 V when in USA or CTR21 DCT. This bit does not modify the DCT
bias voltage.
1
VOL
Line Voltage Tweak.
0 = Nominal
1 = Decreases DC termination voltage
0
FNM
Force Norway Mode.
0 = Default
1 = Norway DCT mode, same as DCT = 00 but without TX attenuation.
Rev. 0.95
59
S i2 40 0
Register F7. DAA Low Level Functions 7
Bit
D7
D6
D5
D4
D3
D2
D1
Name
LM0
LIM
OVL_PROT
Type
R/W
R/W
R/W
D0
Reset settings = 0001_0000
Bit
Name
Function
7:5
Reserved
4
LM0
See LM0 in Register F0 page 54.
3
LIM
Current-Limiting Tweak Value.
Read returns zero.
0 = Disable
1 = Enable (CTR21 mode)
2
OVL_PROT
Overload Protect.
0 = Disable
1 = Enable
1:0
Reserved
Read returns zero.
Register F8. DAA Low Level Functions 8
Bit
D7
D6
D5
Name
LRV
Type
R
Bit
Name
7:4
LRV
D4
D3
D2
Function
Line-Side Chip Revision Number.
0001 = Si3014 Rev A
0010 = Si3014 Rev B
0011 = Si3014 Rev C
1001 = Si3015 Rev A
1010 = Si3015 Rev B
1011 = Si3015 Rev C
3:0
60
Reserved
D1
Read returns indeterministic.
Rev. 0.95
D0
Si2400
Register F9. DAA Low Level Functions 9 Read Only
Bit
D7
D6
D5
D4
D3
D2
D1
Name
OVL
VDD3_DROP
BTD
ROV
Type
R
R
R
R
D0
Reset settings = 0000_0000
Bit
Name
Function
7
Reserved
Read returns zero.
6
OVL
Receive Overload.
Same as ROV, except non-sticky.
5
Reserved
4
VDD3_DROP
Read returns zero.
VDD3 Drop.
0 = Normal
1 = VDD3 drop detected
3
BTD
Billing Tone Detect (sticky).
0 = No billing tone detected
1 = Billing tone detected
2
Reserved
Read returns zero.
1
ROV
Receive Overload.
0 = No excessive level detected
1 = Excessive input level detected (sticky)
0
Reserved
Read returns zero.
Rev. 0.95
61
S i2 40 0
A P P E N D I X A—D AA O P E R A T I O N
Introduction
DAA Isolation Barrier
The Si2400 chipset consists of the Si3015 line-side
device and the Si2400 modem device. The Si2400
achieves an isolation barrier through a low-cost, highvoltage capacitor in conjunction with Silicon
Laboratories’ proprietary ISOcap signal processing
techniques. These techniques eliminate any signal
degradation due to capacitor mismatches, common
mode interference, or noise coupling. As shown in
Figure 3 on page 9, the C1, C2, C24, and C25
capacitors isolate the Si2400 (DSP side) from the
Si3015 (line side). All transmit, receive, and control data
are communicated through this barrier.
Emissions/Immunity
The Si2400 chipset and recommended DAA schematic
is fully compliant with and passes all international
electromagnetic emissions and conducted immunity
tests (includes FCC part 15,68; EN55022; EN50082-1).
Careful attention to the Si2400 bill of materials
(Table 9), schematic (Figure 3), and layout guidelines
(included in the Si2400URT-EVB data sheet) will ensure
compliance with these international standards. In
designs with difficult layout constraints, the addition of
the C31 and C32 capacitors to the C24 and C25
recommended capacitors may improve modem
performance on emissions and conducted immunity. For
such designs, a population option for C31 and C32 may
allow additional flexibility for optimization after the
printed circuit board has been completed.
DC Termination
The Si2400 has three programmable DC termination
modes, selected with the DCT (SF5.3:2).
Japan Mode (DCT = 1), shown in Figure 13, is a lower
voltage mode and supports a transmit full-scale level of
–2.71 dBm. Higher transmit levels for DTMF dialing are
also supported. The low voltage requirement is dictated
by countries such as Japan and Singapore.
USA Mode (DCT = 2), shown in Figure 14, is the default
DC termination mode and supports a transmit full scale
level of –1 dBm at TIP and RING. This mode meets
FCC requirements in addition to the requirements of
many other countries.
CTR21 Mode (DCT = 3), shown in Figure 15, provides
current limiting, while maintaining a transmit full scale
level of –1 dBm at TIP and RING. In this mode, the DC
termination will current limit before reaching 60 mA.
Also, under some layout conditions, C31 and C32 may
improve the immunity to telephone line transients. This
is most important for applications that use the voice
codec feature of the Si2400. Because line transients are
infrequent and high voltage in nature, they tend to be
more problematic in voice applications than in data
applications. An occasional pop in a voice application is
quite noticeable, whereas occasional bit errors are
easily corrected in a modem connection with an errorcorrection protocol.
62
10.5
10
9.5
9
8.5
8
Voltage Across DAA ( V )
This section describes the detailed functionality of the
integrated DAA included in the Si2400 chipset. This
specific functionality is generally transparent to the user
when using the on-chip controller in the Si2400 modem.
When bypassing the on-chip controller, the low-level
DAA functions of the Si3015 described in this section
can be controlled through S registers.
Rev. 0.95
Japan DCT Mode
7.5
7
6.5
6
5.5
.01 .02 .03 .04 .05 .06 .07 .08 .09 .1 .11
Loop Current (A)
Figure 13. Japan Mode I/V Characteristics
Si2400
Voltage Across DAA ( V )
Manual Ring Detection
USA DCT Mode
12
The procedure for manual ring detection is as follows:
The ring signal is capacitively coupled from TIP and
RING to the RNG1 and RNG2 pins. The Si2400
supports either full- or half-wave ring detection. The ring
detection threshold is programmable with RT (SF5.0).
With full-wave ring detection, the designer can detect a
polarity reversal as well as a ring signal.
11
10
9
8
7
A manual ring requires using the register bits RDTP,
RDTN, and RDT in register F2.
6
.01 .02 .03 .04 .05 .06 .07 .08 .09 .1 .11
Loop Current (A)
The host must detect the frequency of the ring signal in
order to distinguish a ring from pulse dialing by
telephone equipment connected in parallel.
The ring detector mode is controlled by RFWE (SF6.4).
When the RFWE is 0 (default mode), the ring detector
operates in half-wave rectifier mode. In this mode, only
positive ringing signals are detected. A positive ringing
signal is defined as a positive voltage greater than the
ring threshold across RNG1-RNG2. RNG1 and RNG2
are pins 5 and 6 of the Si3015. Conversely, a negative
ringing signal is defined as a negative voltage less than
the negative ring threshold across RNG1-RNG2.
Figure 14. USA Mode Characteristics
CTR21 DCT Mode
Voltage Across DAA ( V )
45
40
35
30
25
When the RFWE is 1, the ring detector operates in fullwave rectifier mode. In this mode, both positive and
negative ring signals are detected.
20
15
The RDTP and RDTN behavior is based on the RNG1RNG2 voltage. Whenever the signal RNG1-RNG2 is
above the positive ring threshold, the RDTP bit is set.
Whenever the signal RNG1-RNG2 is below the
negative ring threshold, the RDTN bit is set. When the
signal RNG1-RNG2 is between these thresholds,
neither bit is set.
10
5
.015
.02 .025
.03
.035
.04
.045
.05
.055
.06
Loop Current (A)
Figure 15. CTR21 Mode Characteristics
AC Termination
The Si2400 has two AC termination impedances,
selected with the ACT bit (SF5.4).
ACT=0 is a real, nominal 600 Ω termination which
satisfies the impedance requirements of FCC part 68,
JATE, and other countries. This real impedance is set
by circuitry internal to the Si2400 chipset as well as the
resistor R2 connected to the Si3015 REXT pin.
ACT=1 is a complex impedance which satisfies the
impedance requirements of Australia, New Zealand,
South Africa, CTR21 and some European NET4
countries such as the UK and Germany. This complex
impedance is set by circuitry internal to the Si2400
chipset as well as the network connected to the Si3015
REXT2 pin.
The RD behavior is also based on the RNG1-RNG2
voltage. When RFWE is a 0 or a 1, a positive ringing
signal will set the RD bit for a period of time. The RD bit
will not be set for a negative ringing signal.
The RD bit acts as a one-shot. Whenever a new ring
signal is detected, the one-shot is reset. If no new ring
signals are detected prior to the one-shot counter
counting down to zero, then the RD bit will return to
zero. The length of this count (in seconds) is 65536
divided by the sample rate (9600 Hz). The RD will also
be reset to zero by an off-hook event.
Ringer Impedance
The ring detector in a typical DAA is AC coupled to the
line with a large, 1 uF, 250 V decoupling capacitor. The
ring detector on the Si2400 is also capacitively coupled
to the line, but it is designed to use smaller, less
expensive 1.8 nF capacitors. Inherently, this network
produces a very high ringer impedance to the line on
Rev. 0.95
63
S i2 40 0
the order of 800 to 900 kΩ. This value is acceptable for
most countries, including FCC and CTR21.
Several countries, including the Czech Republic,
Poland, South Africa and South Korea, require a
maximum ringer impedance. For Poland, South Africa
and South Korea, the maximum ringer impedance
specification can be met with an internally synthesized
impedance by setting the RZ bit (SF5.1).
For official Czech Republic designs, an additional
network comprising C15, R14, Z2, and Z3 is required.
See Figure 16. This network is not required for any
other countries. However, if this network is installed, the
RZ bit should not be set for any countries.
C15
From
Line
Z2
Pulse Dialing
Pulse dialing is accomplished by going off and on hook
to generate make and break pulses. The nominal rate is
10 pulses per second. Some countries have very tight
specifications for pulse fidelity, including make and
break times, make resistance, and rise and fall times. In
a traditional solid-state DC holding circuit, there are a
number of issues in meeting these requirements.
The Si2400 DC holding circuit has active control of the
on-hook and off-hook transients to maintain pulse
dialing fidelity.
TIP
R14
Increased distortion may be observed, which is
acceptable during DTMF dialing. After DTMF dialing is
complete, the attenuation should be enabled by setting
the Japan DC termination mode DCT. The FJM bit has
no effect in Japan DC termination mode.
Spark quenching requirements in countries such as
Italy, Netherlands, South Africa and Australia deal with
the on-hook transition during pulse dialing. These tests
provide an inductive DC feed, resulting in a large
voltage spike. This spike is caused by the line
inductance and the sudden decrease in current through
the loop when going on-hook. The traditional way of
dealing with this problem is to put a parallel RC shunt
across the hookswitch relay. The capacitor is large
(~1 uF, 250 V) and expensive. In the Si2400, OHS
(SF5.6:5) can be used to slowly ramp down the loop
current to pass these tests without requiring additional
components.
To
DAA
Z3
RING
Figure 16. Ring Z
Table 23. Ringer Impedance Component Values Billing Tone Detection
Component
Reference
Value
Suppliers
C15
1 µF, 250 V,
X7R, ±20%
Venkel, Johanson,
Panasonic
R14
7.5 kΩ, 1/4 W,
±5%
Z2,Z3
Zener Diode,
5.6 V
Vishay, Motorola,
Rohm
DTMF Dialing
In Japan DC termination mode (DCT[1:0]=01b), the
Si2400 device attenuates the transmit output by 1.7 dB
to meet headroom requirements. This attenuation must
be removed to meet the –6 dB/–8 dB DTMF dialing
levels specified in Singapore, which requires the Japan
DC termination mode. When in the US, DC termination
mode, the FJM bit (SF6.3) will enable the Japan DC
termination mode without the 1.7 dB attenuation.
64
“Billing tones” or “Metering Pulses” generated by the
central office can cause modem connection difficulties.
The billing tone is typically either a 12 KHz or 16 KHz
signal and is sometimes used in Germany, Switzerland,
and South Africa. Depending on line conditions, the
billing tone can be large enough to cause major errors
related to the modem data. The Si2400 chipset has a
feature which allows the device to remain off-hook
during billing tones and provide feedback to the host as
to whether a billing tone has occurred and when it ends.
See Figure 17.
Billing tone detection is enabled by setting the BTE bit
(SF1.7). When a billing tone of sufficient amplitude
occurs, the DC termination is released and the line is
presented with an 800 Ω DC impedance. This is
sufficient to maintain an off-hook condition.
Simultaneously, the following bits will be set:
!
!
!
Rev. 0.95
BTD—Billing Tone Detect (SF9.3)
ROV—Receive Overload (SF9.6)
OVL—Overload Detected (SF9.1)
Si2400
In applications that might be susceptible to billing tones,
the OVL bit should be monitored (polled). When it
returns to zero indicating that the billing tone has
passed, the BTD bit should be written to zero to return
the DC termination to its original state. BTD and ROV
are sticky bits which must be written to zero to reset
them. It will take approximately one second to return to
normal operating conditions. Although the DAA will
remain off-hook during a billing tone event, the received
data from the line will be corrupted when a billing tone
occurs.
If the user wishes to receive data through a billing tone,
an external LC filter must be added. A modem
manufacturer can provide this filter to users in the form
of a dongle that connects on the phone line before the
DAA. This keeps the manufacturer from having to
include a costly LC filter internal to the modem when it
may only be necessary to support only a few countries.
Alternatively, when a billing tone is detected, the host
software may notify the user that a billing tone has
occurred. This notification can be used to prompt the
user to contact the telephone company to have the
billing tones disabled.
In FCC and Japan DC termination modes, an offhook
LCVS value of 63 means the loop current is greater
than 120 mA indicating the DAA is drawing excessive
loop current.
In CTR21 mode, 120 mA of loop current is not possible
due to the current limit circuit. The LCVS bits can be
used to detect excessive line voltage in this mode. They
will report a value of 63 in an overvoltage condition.
Gain Control
The Si2400 supports multiple receive gain settings. The
receive path can support gains of 0, 3, 6, 9, and 12 dB,
as selected by ARG (SF4.6:4).
In-Circuit Testing
The Si2400’s advanced design provides the system
manufacturer with increased ability to determine system
functionality during production line tests, as well as
support for end-user diagnostics. In addition to the local
echo, three loopback modes exist allowing increased
coverage of system components. For two of the test
modes, a line-side power source is needed. While a
standard phone line can be used, the test circuit in
Figure 1 on page 5 is adequate. In addition, an off-hook
sequence must be performed to connect the power
source to the line-side chip.
To test communication with the Si2400 across the
UART, the local echo may by used immediately after
powerup. All other test modes except the analog
loopback mode require setting the UART to a high baud
rate and enabling PCM mode (set PCM (S13.0)=1), as
described in "PCM Data Mode‚" on page 19.
The DSP loopback test mode tests the functionality and
data transfer from the host across the UART RXD pin,
to the Si2400 microcontroller, to the Si2400 DSP filters,
back through the microcontroller, and back across the
UART TXD pin to the host. To enable this mode, set the
UART to PCM mode and set DRT (SE4.5:4) = 2. This
path will introduce approximately 0.9 dB of attenuation
from the RXD received to the TXD. In addition, as
shown in Figure 10C, the ADC from AIN connects
directly through the DAC to AOUT for testing of the
voice codec.
Overload Detection
The remaining test modes requires the Si2400 to be offhook in order to operate. To force the Si2400 off-hook,
set OFHK (SF0.0) = 1. Before running the test mode,
the user must wait 4806/Fs (500 ms) to allow the
Si2400 calibration to occur.
The Si2400 can detect if an overload condition is
present which may damage the DAA circuit. The DAA
may be damaged if excessive line voltage or loop
current is sustained.
The ISOcap digital loopback mode allows the host to
provide a digital test pattern on RXD and receive that
test pattern on TXD. To enable this mode, set DL
(SF1.0) = 1. In this mode, the isolation barrier is actually
Figure 17. Billing Tone Filter
Rev. 0.95
65
S i2 40 0
being tested. The digital stream is delivered across the
isolation capacitor, C1 of Figure 3 on page 9, to the line
side device and returned across the same barrier. Note
that in this mode, the 0.9 dB attenuation also exists.
The final testing mode, internal analog loopback, allows
the system to test the basic operation of the transmit
and receive paths on the line-side chip and the external
components in Figure 3 on page 9. In this test mode, the
host provides a digital test waveform on RXD. This data
is passed across the isolation barrier, transmitted to and
received from the line, passed back across the isolation
barrier, and presented to the host on TXD. To enable
this mode, clear HBE (SF1.2).
When the HBE bit is cleared, this will cause a DC offset
which affects the signal swing of the transmit signal. In
this test mode, it is recommended that the transmit
signal be 12 dB lower than normal transmit levels. This
lower level will eliminate clipping caused by the DC
offset which results from disabling the hybrid. It is
assumed in this test that the line AC impedance is
nominally 600 Ω.
Note: All test modes are mutually exclusive. If more than one
test mode is enabled concurrently, the results are
unpredictable.
66
Rev. 0.95
Si2400
A P P E N D I X B—T Y P I C A L M O D E M A P P L I C A T I O N S E X A M P L E S
Introduction
Appendix B outlines the steps required to configure the
Si2400 for modem operation under typical examples.
The ISOmodem has been designed to be both easy to
use and flexible. The Si2400 has many features and
modes, which add to the complexity of the device, but
are not required for a typical modem configuration. The
goal of this appendix is to help the user to quickly make
a modem connection and begin evaluation of the
Si2400 under various operational examples.
Example 1: V.22bis in FCC countries
1. Power on reset
2. Set Host UART to 2400 bps
3. ATS07=06 set for QAM 2400 bps
4. ATDT18005551212<CR>
Si2400 may echo the following:
R – Ringback
b – busy tone
N – No carrier
c – connect
d – connect at 1200bps
5. Next byte after “c” or “d” is modem data!
Example 2: V.22 in CTR21 countries
c – connect
6. Next byte after “c” is modem data!
Example 4: Bell 103 in Australia with
Parallel Phone Detect
1. Power on reset
2. Set Host UART to 2400 bps
3. ATS07=01 (set for FSK 300 bps)
4. ATSF5=78 (set DAA for Australia)
5. ATSE2=C0 (enable ALERT pin)
6. ATDT18005551212<CR>
Si2400 may echo the following:
R – Ringback
b – busy tone
N – No carrier
c – connect
7. Next byte after “c” is modem data!
Example 5: Bell 212A in South Korea with
Japanese caller ID
1. Power on reset
2. Set Host UART to 2400 bps
3. ATS07=00 (set for DPSK 1200 bps)
1. Power on reset
4. ATSF5=06(set DAA for South Korea)
2. Set Host UART to 2400 bps
5. ATS13=80 (set caller ID to Japanese format)
When caller ID data is detected, Si2400 will echo “f”
indicating the line reversal, “m” indicating the mark, and
then caller ID data will follow.
3. ATS07=02 (set for DPSK 1200 bps)
4. ATSF5=1C (set DAA for CTR21)
5. ATSF7=1C (set DAA for CTR21)
6. ATDT18005551212<CR>
Si2400 may echo the following:
R – Ringback
b – busy tone
N – No carrier
c – connect
7. Next byte after “c” is modem data!
Example 3: Bell 103 in Australia
1. Power on reset
2. Set Host UART to 2400 bps
3. ATS07=01 (set for FSK 300 bps)
4. ATSF5=78 (set DAA for Australia)
5. ATDT18005551212<CR>
Si2400 may echo the following:
R – Ringback
b – busy tone
N – No carrier|
6. ATDT18005551212<CR>
-Si2400 may echo:
R – Ringback
b – busy tone
N – No carrier
c – connect
7. Next byte after “c” is modem data!
Example 6: Security Application Example—
SIA P3 Pulse Format in CTR21 Countries
1. Power On Reset
2. ATSF5=1C<CR> (Si3015 DAA set ringer threshold, AC
termination, etc. for CTR21)
3. ATSF7=1C<CR>
4. ATDT149109933!322292229<CR>
Rev. 0.95
67
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A P P E N D I X C—U L1 950 3 R D E D I T I O N
Designs using the Si2400 pass all overcurrent and overvoltage tests for UL1950 3rd Edition compliance with a
couple of considerations.
Figure 18 shows the designs that can pass the UL1950
overvoltage tests, as well as electromagnetic
emissions. The top schematic of Figure 18 shows the
configuration in which the ferrite beads (FB1, FB2) are
on the unprotected side of the sidactor (RV1). For this
configuration, the current rating of the ferrite beads
must be 6 A.
The bottom schematic of Figure 18 shows the
configuration in which the ferrite beads (FB1, FB2) are
on the protected side of the sidactor (RV1). For this
design, the ferrite beads can be rated at 200 mA.
In a cost-optimized design, it is important to remember
that compliance to UL1950 does not always require
overvoltage tests. It is best to plan ahead and know
which overvoltage tests will apply to your system.
System-level elements in the construction, such as fire
enclosure and spacing requirements, need to be
considered during the design stages. Consult with your
Professional Testing Agency during the design of the
product to determine which tests apply to your system.
C24
75 Ω @ 100 MHz, 6 A
1.25 A
FB1
TIP
Fuse/PTC
75 Ω @ 100 MHz, 6 A
RV1
FB2
RING
C25
Note: In this configuration, C24 and C25 are
used for emissions testing.
1000 Ω @ 100 MHz, 200 mA
C24
1.25 A
FB1
TIP
Fuse/PTC
1000 Ω @ 100 MHz, 200 mA RV1
FB2
RING
C25
Figure 18. Circuits that Pass all UL1950 Overvoltage Tests
68
Rev. 0.95
Si2400
Pin Descriptions—Si2400
XTALI
1
16
GPIO1
XTALO
2
15
GPIO2
CLKOUT
3
14
GPIO3
VD
4
13
ISOB
TXD
5
12
GND
RXD
6
11
C1A
CTS
7
10
GPIO4
RESET
8
9
AOUT
GPIO3
General Purpose Input/Output 3—This
pin can be either a GPIO pin (analog in,
digital in, digital out) or the ESC pin.
Default is digital in. When programmed as
ESC, a positive edge on this pin will cause
the modem to go from online (connected)
mode to the offline (command) mode.
GPIO4
General Purpose Input/Output 4—This
pin can be either a GPIO pin (analog in,
digital in, digital out) or the ALERT pin.
Default is digital in. When programmed as
ALERT, this pin provides two functions.
While the modem is connected, it will
normally be low, but will go high if the
carrier is lost or if an intrusion event has
been detected. The ALERT pin is sticky,
and will stay high until the host clears it by
writing to the correct S register.
Serial Interface
XTALI/XTALO Crystal Oscillator Pins—These pins
provide support for parallel resonant,
AT cut crystals. XTALI also acts as an
input in the event that an external clock
source is used in place of a crystal.
XTALO serves as the output of the
crystal amplifier. A 4.9152 MHz crystal
is required or a 4.9152 MHz clock on
XTALI.
CLKOUT
Clock Output—This signal is typically
used to clock an output system
microcontroller. The frequency is
78.6432 MHz/(N+1), where N is
programmable from 0 to 31. N defaults
to 7 on power up. Setting N = 0 stops
the clock.
RXD
Receive Data—Serial
data input.
communication
TXD
Transmit Data—Serial
data output.
communication
GPIO1
General Purpose Input Output 1— This
pin can be either a GPIO pin (analog in,
digital in, digital out) or the TXD2 pin.
Default is digital. The user can program
this pin to function as TXD2 if the
secondary serial interface is enabled. This
pin can also be programmed to function as
the EOFR (end of frame receive) signal for
HDLC framing.
GPIO2
General Purpose Input Output 2—This
pin can be either a GPIO pin (analog in,
digital in, digital out) or the RXD2 pin.
Default is digital in. The user can program
this pin to function as RXD2 if the
secondary serial interface is enabled.
Control Interface
CTS
Clear to Send—Clear to send output used
by the Si2400 to signal that the device is
ready to receive more digital data on the
receive data pin.
RESET
Reset Input—An active low input that is
used to reset all control registers to a
defined, initialized state. Also used to bring
the Si2400 out of sleep mode.
Miscellaneous Signals
AOUT
Analog Speaker Output—Provides an
analog output signal for monitoring call
progress tones or to output voice data to a
speaker.
C1A
Isolation Capacitor 1A—Connects to one
side of the isolation capacitor C1.
ISOB
Isolink Bias Voltage—This pin should be
connected to a .1 µf cap to ground.
Power Signals
VD
Digital Supply Voltage—Provides the
digital supply voltage to the Si2400.
Nominally either 5 V or 3.3 V.
GND
Ground—Connects to the system digital
ground.
Rev. 0.95
69
S i2 40 0
Pin Descriptions—Si3015
QE2
DCT
IGND
C1B
RNG1
RNG2
QB
QE
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
Isolation
FILT2
FILT
Isolation Capacitor 1B—Connects to one
side of isolation capacitor C1.
IGND
Isolated Ground—Connects to ground on
the line-side interface. Also connects to
capacitor C2.
RX
REXT
Miscellaneous
REXT2
REF
VREG2
VREG
Voltage Regulator—Connects to an
external capacitor to provide bypassing for
an internal power supply.
VREG2
Voltage Regulator 2—Connects to an
external capacitor to provide bypassing for
an internal power supply.
VREG
Line Interface
FILT
Filter—Sets the time constant for the DC
termination circuit.
FILT2
Filter 2—Sets the time constant for the DC
termination circuit.
RX
Receive Input—Serves as the receive
side input from the telephone network.
DCT
DC
Termination—Provides
DC
termination to the telephone network and
input for line voltage monitors.
REXT
External Resistor—Sets the real AC
termination impedance.
REXT2
External Resistor 2—Sets the complex
AC termination impedance.
RNG1
Ring 1—Connects through a capacitor to
the TIP lead of the telephone line.
Provides the ring and caller ID signals to
the Si2400.
RNG2
Ring 2—Connects through a capacitor to
the RING lead of the telephone line.
Provides the ring and caller ID signals to
the Si2400.
QB
Transistor Base—Connects to the base
of transistor Q3.
QE
Transistor Emitter—Connects
emitter of transistor Q3.
QE2
Transistor Emitter 2—Connects to the
emitter of Q4.
REF
Reference—Connects to an external
resistor to provide a high accuracy
reference current.
70
C1B
to
the
Rev. 0.95
Si2400
Ordering Guide
Table 24. Ordering Guide
Chipset
Region
Power Supply
Digital
Line
Temperature
Si2400
Global
3.3/5 V Digital
Si2400-KS
Si3015-KS
0°C to 70°C
Si2400
Global
3.3/5 V Digital
Si2400-BS
Si3015-BS
–40°C to 85°C
Rev. 0.95
71
S i2 40 0
Package Outline
Figure 19 illustrates the package details for the Si2400 and Si3015. Table 25 lists the values for the dimensions
shown in the illustration.
Figure 19. 16-pin Small Outline Plastic Package (SOIC)
Table 25. Package Diagram Dimensions
Controlling Dimension: mm
Symbo
l
72
Inches
Millimeters
Min
Max
Min
Max
A
0.053
0.069
1.35
1.75
A1
0.004
0.010
0.10
0.25
A2
0.051
0.059
1.30
1.50
b
0.013
0.020
0.330
0.51
c
0.007
0.010
0.19
0.25
D
0.386
0.394
9.80
10.01
E
0.150
0.157
3.80
4.00
e
0.050 BSC
—
1.27 BSC
—
H
0.228
0.244
5.80
6.20
L
0.016
0.050
0.40
1.27
L1
0.042 BSC
—
1.07 BSC
—
γ
—
0.004
—
0.10
θ
0°
8°
0°
8°
Rev. 0.95
Si2400
Rev 0.9 to Rev 0.95 Change List
!
!
!
!
!
!
The Power Supply Current numbers in Table 3 have
been updated.
The Power Supply Current numbers in Table 4 have
been updated.
The TBDs in Table 5 have been updated.
Table 6 has been updated.
The Typical Application Schematic has been
updated.
The Bill of Materials has been updated.
Rev. 0.95
73
S i2 40 0
Si2400 Silicon Rev. B to Rev. C Change List
Note: The change from Si2400 rev. B to Si2400 rev. C is a
ROM change only.
!
!
!
!
!
!
!
!
74
In PCM data mode, when using the UART 9th-bit
escape feature or the GPIO3 escape pin, an escape
when off-hook causes the Si2400 rev. B to go back
on-hook. This errata has been eliminated in the
Si2400 rev. C.
The following command, 'SF5=0AS09=50', is
required by the Si2400 rev. B upon initialization to
improve ring detection. The Si2400 rev. C does not
require this command.
The S01 register defaults to 0x01 in rev. B and has
changed to a default of 0x03 in rev. C. This default
value of 0x03 seconds is needed for JATE
compliance during blind dialing.
The S08 register defaults to 0x0F in rev. B and has
changed to a default of 0x0A in rev. C. This default
value of 0x0A corresponds to a setting which allows
for CTR21 ring-frequency compliance.
FCC Part 68 requires that answering modems have
a two second delay from off hook to answer tone
generation. Implementations that use that autoanswer mode with the Si2400 rev. B must instead
issue the command 'ATDT,,;ATA' immediately after
ring detection to answer an incoming call. This
command is not required for the Si2400 rev. C.
In order to force the modem to stay off hook when
using the 'ATA0' command, the 'ATSB3=66SB2=00'
command is required before the 'ATA0' command for
the Si2400 rev. B. This command is not required for
the Si2400 rev. C.
For the Si2400 rev. B, after caller ID data has been
received by the Si2400, the Si2400 does not
respond to an ATA <CR> command until after a
second ring has been received. In order to answer
the call before the second ring, a hidden register, the
S84.7 bit, must be cleared prior to issuing the
ATA<CR> command. Clearing this bit is not required
on the Si2400 rev. C.
For the Si2400 rev. B, under certain loop conditions,
the Si2400 indicates a false off-hook intrusion event
and asserts ALERT (if enabled) when the Si2400
goes off-hook. The workaround for Rev B is to clear
the GPIO4 data bit after going off hook to force the
negation of the ALERT pin. Instead of using an
ATDT####<CR> sequence to originate a call, the
sequence ATDT,;ATSE3=00DT####<CR> is used.
Instead of using automatic answer (ATS00=01) to
answer a call, the ATDT,;ATSE3=00A<CR> is used
after a ring has been detected via the 'R' result code.
!
!
!
Rev. 0.95
Neither of these software workarounds are required
in the Si2400 rev. C.
For the Si2400 rev. B, register 0x3B must be set to
0x03 to improve caller ID in Australia. This is not
required for the Si2400 rev. C.
For the Si2400 rev. B, when using the Analog
Monitor Mode of operation (ATDT###!0 or ATA0), the
host must wait for a ',' result code and then send the
ATSE4=12A0 command, or the host must send the
command ATSF4=00SE4=12 after a connection is
made. Neither of these workarounds are required
with the Si2400 rev. C.
For the Si2400 rev. C, the definition of register 0x0B
has changed from Minimum Ring ON time to
Minimum Ring OFF time, and the default is set to
0x28.
Si2400
NOTES:
Rev. 0.95
75
S i2 40 0
Contact Information
Silicon Laboratories Inc.
4635 Boston Lane
Austin, TX 78735
Tel: 1+(512) 416-8500
Fax: 1+(512) 416-9669
Toll Free: 1+(877) 444-3032
Email: [email protected]
Internet: www.silabs.com
The information in this document is believed to be accurate in all respects at the time of publication but is subject to change without notice.
Silicon Laboratories assumes no responsibility for errors and omissions, and disclaims responsibility for any consequences resulting from
the use of information included herein. Additionally, Silicon Laboratories assumes no responsibility for the functioning of undescribed features
or parameters. Silicon Laboratories reserves the right to make changes without further notice. Silicon Laboratories makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does Silicon Laboratories assume any liability
arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation consequential or incidental damages. Silicon Laboratories products are not designed, intended, or authorized for use in applications intended to
support or sustain life, or for any other application in which the failure of the Silicon Laboratories product could create a situation where personal injury or death may occur. Should Buyer purchase or use Silicon Laboratories products for any such unintended or unauthorized application, Buyer shall indemnify and hold Silicon Laboratories harmless against all claims and damages.
Silicon Laboratories, Silicon Labs, ISOcap, and ISOmodem are trademarks of Silicon Laboratories Inc.
Other products or brandnames mentioned herein are trademarks or registered trademarks of their respective holders
76
Rev. 0.95