Compact 1200 bps Modem
XE1276A
2/97
Description
The XE1276A is the successor to the XE1276.
Several improvements have been incorporated in
the XE1276A. Power consumption has been
reduced, an automatic Sleep mode has been
added and the XE1276A includes non-volatile
memory for storage of the "AT" Commands used
for modem control and configuration.
The XE1276A provides a replacement for the
CH1776. Most OEM's currently using the CH1776
can use the XE1276A without altering their existing
hardware or software. The XE2476 provides a
2400 bps upgrade in the same package design.
The XE1276A includes user transferable FCC Part
68 registration. This permits use of the XE1276A
without additional FCC Part 68 testing.
Features
Modem Protocols Supported:
V.22, V.21, Bell 212A and 103
Pin compatible with the XE1276, XE2476 and
CH1776
Command set: "AT" command set for modem
control and configuration.
Modem Configuration stored in NVRAM
Small Size: 2.00 inches long, 1.125 inches wide,
0.44 inches high.
Single +5V supply
Low power CMOS:
Operating: 200 mW (Typical)
Sleep: 50 mW (maximum)
xecom
Block Diagram
1
18
2
17
3
16
4
5
6
7
8
9
10
11
12
13
15
14
TST
N/C
N/C
/DCD
/DTR
D/V
OHO
RXD
TXD
N/C
SPK
VO
VI
RI
GND
VCC
RING
TIP
PIN CONFIGURATION
XE1276A
(Top View)
XECOM
(2)
XE1276A
A
1.990
2.010
50.55
51.05
B
1.115
1.135
28.32
28.83
C
0.420
0.430
10.67
10.92
D
0.100
0.120
2.54
3.05
E
0.890
0.910
22.61
23.11
F
0.090
0.110
2.29
2.79
G
0.090
0.110
2.29
2.79
H
0.190
0.210
4.83
5.33
I
0.020
0.025
0.51
0.64
J
0.125
0.200
3.18
5.08
XE1276A Mechanical Specifications
Pins = 0.025 square pin
recommended hole size 0.056"
INCHES
METRIC(MM)
PIN MIN
MAX
MIN
MAX
ABSOLUTE MAXIMUM RATINGS*
SUPPLY VOLTAGE - Vcc
+6.5 Volts
DC INPUT VOLTAGE
-0.6 Volts to +6.5 Volts
STORAGE TEMPERATURE RANGE
-25 C TO +100 C
LEAD TEMPERATURE (Soldering, 2 sec per wave)
260 C
OPERATING TEMPERATURE RANGE
0 TO 70 C
*Exceeding these values may result in permanent damage to the device.
Symbol
Parameter
Min
Typ
Max
Units
Comments
Vcc
Supply Voltage
4.75
5.0
5.25
V
Icc
Vcc Supply Current
40
50
mA
On-Line All outputs
Disconnected
Icc
Vcc Supply Current
7
10
mA
Sleep Mode
Power Supply Characteristics
(TA = 0 - 70C, Vcc = 5v 5%)
Sleep Mode:
The XE1276A has an integrated, advanced power management capability. If no activity is detected
on the RXD, DTR, or RI lines the modem will automatically go into a smart power down mode. In this mode power
consumption is less than 50 milliwatts.
XECOM
(3)
XE1276A
Pin Descriptions
PIN NAME
DESCRIPTION
1
TST
This output is for Xecom test purposes only;
2
N/C
No Connection
3
N/C
No Connection
4
\DCD
DCD, Data Carrier Detect, is an active low output from the modem. DCD goes low to
indicate receipt of a valid carrier signal.
5
\DTR
DTR, Data Terminal Ready, is an active low input to the modem. DTR must be present for
the XE1276A to remain on line. If DTR goes high while the modem is on line, the modem
disconnects immediately. The XE1276A will not automatically answer an icoming call if DTR
is not active.
6
D/V
The D/V, Data/Voice, output can be used to drive a relay to connect an auxiliary telephone
handset. D/V is high when the modem is off-hook And low when the modem is on-hook.
7
OH
OH, Off-Hook, is an active high output which indicates that the XE1276A is connected to the
telephone line.
8
RXD
RXD, Received Data, provides the serial data output path from the modem. A logic "high"
represents a "mark" and a logic "low" represents a "space".
9
TXD
TXD, Transmit Data, provides the serial data input path from the host. A logic "high"
represents a "mark" and a low represents a"space", TTL.
10
N/C
No Connection
11
SPK
SPK, Speaker, provides the Audio output to the modem speaker. Speaker operation is
determined by the ATL and ATMM commands . This output can drive a 300 ohm load.
12
VO
The Modem Line Interface permits placement of non-modem signals on the telephone line
through the modem's telephone interface. VO must be tied to VI for normal modem operation
and open to place non-modem signals on the line through VI.
13
VI
VI, Voice Interface, provides a path for non-modem signals to be placed on the telephone line
through the modem's telephone interface. VI must be tied to VO for modem operation.
14
TIP
Tip connection to the phone line(RJ11 pin3) from the internal DAA.
15
RING
Ring connection to the phone line(RJ11 pin4) from the internal DAA.
16
Vcc
+5 Volt power for the modem.
17
GND
Ground reference for the modem.
18
RI
RI, Ring Indicator, provides an active high output whenever a ring signal appears on the
telephone line.
XECOM
(4)
XE1276A
AT Commands
The XE1276A uses "AT" commands for modem config-
uration. This section describes the command format
and lists the commands, registers and result codes.
Modes of Operation
The "AT" commands have two operational modes;
Command Mode and Data Mode.
Data Mode: The XE1276A enters data mode upon
connecting with a remote modem and i ssues an
appropriate "CONNECT" result code. In Data Mode the
modem sends all data presented on Transmit Data
(TXD) to the remote modem and places demodulated
data from the remote modem onto Received Data
(RXD). When the modem exits data mode, it issues the
"NO CARRIER" result code.
Command Mode: The XE1276A enters command
mode on power-up, reset, a lost connection, or receipt
of the escape code. In command mode the modem
accepts commands from the host on transmit data.
Appropriate result codes are returned on received data.
Command Line Format
Command lines issued to the modem follow a strict
format. Each command begins with the prefix AT. The
command line is stored in the command buffer and
executed upon receipt of a carriage return. Until
executed, the command line can be edited with the
backspace key.
Command Prefix - Commands, except A/, begin with
the AT prefix. The "A" and "T" may be both upper case
or both lower case but cannot be of different cases. The
prefix identifies the speed and parity of the commands
sent by the host. Speed is determined by measuring the
width of the incoming bits. Parity is determined by
comparing the parity bits of the "A" and "T."
Command Line - Commands may be strung together
in a single command line of up to 40 characters.
Commands are executed in the sequence they appear.
A carriage return terminates the command line and
causes the commands to be executed. Register S3
allows the user to select a character other than a
carriage return to terminate the command line.
Command Buffer - The command buffer stores up to
40 characters, including the AT prefix, from one
command line. Spaces may be inserted into the
command line without filling space in the command
buffer. If the command buffer overflows, the modem
issues an "ERROR" result code and commands are not
executed.
Command Line Editing - A backspace can be used to
edit a command line before execution. The backspace
key, (Control and H simultaneously on some systems),
erases the previous character in the command line.
Register S5 allows the user to select a character other
than a backspace as the command line editor.
Re-Execute Last Command - The A/ command
causes the modem to reexecute the last command line.
This command does not require the "AT" prefix.
Omitted Parameters - Most commands include a
parameter which determine the function setting. When
the command parameter is omitted from the command
string, it is assumed to be a 0.
Escape Characters - An escape sequence may be
entered while in data mode to switch the modem into
command mode while on line. The escape character,
set b y Register S2, must be entered 3 times in
succession within a 1 second guard time to execute the
escape. The default escape sequence is "+++."
Result Codes - The modem issues a result code after
each action. Result codes may be provided as full
words, numeric codes or may be disabled all together.
Each result code ends with a carriage return when
numeric result codes are chosen. When full word result
codes are chosen, a Line feed and Carriage Return
preceed and follow each result code.
XECOM
(5)
XE1276A
XE1276A AT Command List
A - Answer Command -
Bn - Select Communications Standard
n=0
Selects CCITT standards
n=1
Selects Bell standards*
D - Dial Command -
P =
Pulse dial
T =
Tone dial
R =
Connect as an answering modem
W =
Wait for dial tone
, =
Pause for the duration of S8
@ =
Wait for silence
! =
Switch hook flash
; =
Return to the command state
Sn =
Dial number stored in location n
En - Command Echo
n=0
Do not echo commands
n=1
Enable command echo*
Hn - Switch Hook Control -
n=0 Switch hook relay closes*
n=1 The switch hook relay opens
In - Modem Identification
Ln - Speaker Volume -
n=0
Low speaker volume
n=1
Low speaker volume
n=2
Moderate speaker volume*
n=3
High speaker volume
Mn - Speaker Activity -
n=0
Speaker off
n=1
Speaker on until carrier received*
n=2
Speaker remains on
n=3
Speaker on after dialing until carrier detected.
On - On Line
n=0
Return On Line with no retrain*
n=1
No response to remote test request.
n=2
Initiate Remote Digital Loopback
Qn - Responses
n=0
Send responses *
n=1
No Responses
Sr? - Interrogate Register -
Sr=n - Set Register Value -
Vn - Result Codes -
n=0
Numeric Result Codes
n=1
English Word Result Codes*
Xn - Result Code Set -
n=0
Responses 0-4*
n=1
Responses 0-5
n=2
Responses 0-6
n=3
Responses 0-5, & 7
n=4
Responses 0-8
Z - Reset -
&Cn - DCD Operation
n=0
DCD is forced active
n=1
DCD indicates a valid carrier signal*
&Dn - DTR
n=0
DTR is ignored by the modem
n=2
Modem disconnects if DTR revoked.*
n=3
The modem performs a soft reset when DTR
is revoked.
&F - Use XE2476 Defaults
&Tn - Test Modes
n=0
Exit test mode
n=1
Local analog loopback
n=3
Initiate local digital loopback
n=4
Respond to remote loop request*
n=5
Deny remote loop request
n=6
Initiate a Remote Digital loopback
n=7
Remote digital loopback w self-test
n=8
Local analog loopback w self-test
&V - View Active Profile -
&Wn - Store Profile -
n=0
Stores the current configuration in memory
location 0.
n=1
Stores the current configuration in memory
location 1.
&Yn - Recall Profile
n=0
Use memory location 0.
n=1
Use memory location 1.
&Zn=X- Store Number
* Indicates the default setting for the command as
shipped by Xecom.
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