V-Stamp User`s Manual
V-Stamp
RC Systems
voice synthesizer
now you’re talking!
V-Stamp™
CMOS, 3.3 Volt / 5 Volt
Voice Synthesizer Module
Features
•Based on RC Systems’ RC8660 chipset
•Integrated text-to-speech processor:
– High voice quality, unlimited vocabulary
– Converts any ASCII text into speech automatically
– Add/modify messages by simply editing a text file
– On-the-fly control of speed, pitch, volume, etc.
•Four channel, 8-bit A/D converter
•Record, download, upload, and play sound files:
– Record and/or download to onboard recording memory
– Internal file system for easy management of recordings
– Data logging mode
– Recording times from 2 min to 33 min available
•Tone generation:
– Three voice musical
– Dual sinusoidal
– DTMF (Touch-Tone) dialer
Applications
•Robotics
•Electronic test and measurement
•GPS navigation systems
•Meeting federal ADA requirements
•Talking e-mail/telecommunications
•Remote diagnostic reporting
•ATM machines
•Dial-up information systems
•Vending and ticketing machines
•Industrial controllers
•Security and warning systems
•Aids for the orally or visually disabled
•Flexible user exception dictionary:
– Change the pronunciation of any input string based on
spelling and context
– Convert encrypted data into meaningful messages
– Trigger tone generation, message playback, voice changes
•8 KB input buffer for “print-and-forget” TTS operation
•1 W audio output power can directly drive an 8 ohm speaker
•Standard asynchronous serial interface
•Low power (typ @ 3.3 V, excluding audio power amplifier):
– 3.8 mA active
– 700 µA idle
– 0.7 µA standby
General Description
The V-Stamp is a feature-rich, self-contained voice/sound synthesizer and recorder, measuring only 1.7 square inches (10.9 cm2) in
size. Among the V-Stamp’s many features are text-to-speech conversion, audio recording and playback, musical and sinusoidal tone
generation, a telephone dialer and four-channel A/D converter. All
features are accessed using a standard logic-level serial interface.
V-Stamp Product Summary
The V-Stamp mates with two standard, 12-pin PC board connectors. Separate power pins are provided for the onboard digital and
audio subsystems, allowing for several possible output power and
power consumption combinations.
For additional information about using and programming the
V-Stamp, please refer to the DoubleTalk RC8660 Chipset User’s
Manual, available from www.rcsys.com.
V-Stamp User’s Manual Rev 03
Revised 1/21/09
Order
Number
Operating
Voltage
Recording
Capacity *
Chipset
VS5130
5V
2 min
RC8660F1C
VS3130
VS3910
3.3 V
3.3 V
2 min
15 min
RC86L60F1I
RC86L60F3I
VS3950
3.3 V
33 min
RC86L60F4I
* Based on 8 kHz sampling rate with ADPCM encoding
1
© 2004 – 2009 RC Systems, Incorporated
V-Stamp
RC Systems
voice synthesizer
now you’re talking!
Pin Configuration
Typical Application Circuit

RES#
TS
AN3
AN2
AN1
AN0
AMPOUT
AMPIN
LINE
MUTE#
SP+
SP–
24
1
TOP
VIEW
VSS
SUSP#
STBY#
CTS#
RXD
TXD
BRS0
BRS1
BRS2
BRS3
VCC
VPA
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Functional Block Diagram
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V-Stamp
RC Systems
voice synthesizer
now you’re talking!
Pin Descriptions
Pin Name
Type
Name and Function
LINE
INPUT/
OUTPUT
LINE: High impedance, unfiltered audio output; also feeds into onboard audio subsystem. Output voltage
range is from 0 V to VCC. External audio sources may also be resistively summed with the V-Stamp’s audio
and amplified through this pin.
SP +
SP –
OUTPUT
SPEAKER: Low impedance, filtered, differential audio output that can deliver up to 1 W into an 8 ohm load.
Output power is a function of the voltage on the VPA pin and Volume command setting. A DC voltage of
VPA / 2 is present on each pin when MUTE# is High; both pins enter a high-impedance state when MUTE# is
Low. Do not connect either pin to a low impedance ground-referenced load without a DC blocking capacitor.
TS
OUTPUT
TALK STATUS: Indicates when the V-Stamp is active. TS can be used to enable devices such as a transmitter, telephone, or audio amplifier. The pin’s polarity is programmable, and can be activated automatically or
under program control.
SUSP#
INPUT
SUSPEND: Suspends audio output when Low, allowing playback to be paused. When High, playback resumes at the point output was suspended. During recording operations, SUSP# suspends recording when
Low. SUSP# can also be used to suspend the transfer of a file while a file is being uploaded from recording
memory. Connect this pin to a High level if not used.
MUTE#
INPUT
MUTE: Shuts down the audio subsystem when Low, reducing the VPA pin current to less than 1 µA. The SP
pins also enter a high-impedance state when MUTE# is Low. Connecting this pin to the TS pin will cause
the amplifier circuit to automatically shut down whenever the V-Stamp is inactive, thus conserving power.
AN0 – AN3
INPUT
A/D CONVERTER INPUTS: Analog to digital converter input pins. Analog signals sampled on these pins can
be read through the serial interface, or stored in recording memory. Leave any unused pins unconnected.
OUTPUT
A/D CONVERTER AMPLIFIER: Connecting an operational amplifier between these pins allows the input voltage to all four A/D converter input pins to be amplified with one operational amplifier. Leave these pins
unconnected if not used.
AMPIN
AMPOUT
INPUT
RXD
INPUT
TXD
OUTPUT
TRANSMIT DATA: Asynchronous serial data output used to read information out of the V-Stamp.
CTS#
OUTPUT
CLEAR TO SEND: The CTS# pin is Low when the V-Stamp is able to accept data. If the input buffer becomes
full as a result of the last byte received, CTS# will go High and remain High until room becomes available.
BRS0 –
BRS3
INPUT
BAUD RATE SELECT: Programs the V-Stamp’s serial port baud rate. Both the RXD and TXD pins are programmed to the rate set by these pins. Connecting BRS0 – BRS3 to a High level allows the V-Stamp to automatically detect the incoming baud rate.
STBY#
INPUT
STANDBY: A Low immediately terminates all activity and places the V-Stamp in Standby mode. The CTS#
pin is driven High (“not ready” state), and the input buffer is cleared. During standby, the V-Stamp draws
the minimum possible current (0.7 µA typ @ 3.3 V), but it is not able to respond to any input pin except
STBY# and RES#. Returning STBY# High causes the V-Stamp to enter Idle mode (700 µA typ); the CTS# pin
is driven Low and the V-Stamp will be able to accept input again. If the V-Stamp entered standby due to a
Sleep Timer event, driving STBY# Low for 250 ns or longer then High will return the V-Stamp to Idle mode.
RECEIVE DATA: Asynchronous serial data input used to send text, data and commands to the V-Stamp. Uses
standard protocol of 8 data bits,1 stop bit, no parity.
STBY# is also used to restore the V-Stamp to its factory default settings. To prevent this from happening
unintentionally, make sure that STBY# is High no later than 0.5 sec after RES# goes High. See Appendix D:
Restore Mode in the DoubleTalk RC8660 User’s Manual for additional information.
Connect this pin to a High level if not used.
RES#
INPUT
RESET: A Low immediately terminates all activity and sets all pins to a predetermined state. During powerup, RES# must be held Low a minimum of 1 ms after VCC has stabilized in the proper voltage range. All pins
will be valid within 2 ms after reset.
Table 1. Pin Descriptions
3
V-Stamp
RC Systems
voice synthesizer
now you’re talking!
Pin Name
Type
Name and Function
VCC
DIGITAL POWER: + 5 V ± 0.5 V or + 3.3 V ± 0.3 V digital subsystem power supply connection.
VPA
AUDIO POWER: Power supply connection for the audio subsystem. Connect this pin to a supply voltage
between + 3.0 V and + 5.5 V (+ 5 V recommended in order to achieve maximum power output). If the audio
subsystem is not used (output is taken from the LINE pin instead of the SP pins), this pin may be left
unconnected.
VSS
GROUND: Connect to system ground.
Table 1. Pin Descriptions (Continued)
Functional Description
Touch-Tone Generator
The V-Stamp includes an integrated DTMF (Touch-Tone) generator.
This is useful in telephony applications where standard DTMF tones
are used to signal a remote receiver, modem, or access the public
switched telephone network.
The V-Stamp includes a number of features that make it ideally
suited for any design requiring voice output. The V-Stamp’s major
features are described below. For detailed information about using
and programming the V-Stamp, refer to the DoubleTalk RC8660
Chipset User’s Manual.
Sinusoidal Tone Generator
A precision, dual sinusoidal tone generator can synthesize the tones
often used in signaling applications. The tone frequencies can be
independently set, allowing signals such as call-progress tones to
be generated.
Text-to-Speech Synthesizer
The V-Stamp provides text-to-speech conversion with its integrated
DoubleTalk™ text-to-speech synthesizer. Any English text written to
the V-Stamp is automatically converted into speech. Commands
can be embedded in the input stream to dynamically control the
voice, even at the phoneme level (phonemes are the basic sound
units of speech).
Analog-to-Digital Converter
The four channel, 8-bit A/D converter can be used to monitor battery cell voltages, temperature, and other analog quantities. The
ADC can be programmed on the fly to convert any single channel,
or scan up to four channels repetitively. Data logging and audio
recording to the V-Stamp’s recording memory are also possible
through the ADC.
A greeting message can be stored in the V-Stamp that is automatically spoken immediately after the V-Stamp is reset. Most any of the
commands recognized by the V-Stamp may be included as part of
the greeting message, which can be used to set up custom default
settings and/or play a pre-recorded message or tone sequence. An
integrated nonvolatile memory area is also provided for storing a
custom pronunciation dictionary, allowing the pronunciation of any
character string to be redefined.
Audio Subsystem
Audio Recording and Playback
The V-Stamp includes an audio subsystem, comprised of a lowpass filter and audio power amplifier. This subsystem operates independently of the V-Stamp’s digital subsystem; a separate power
pin, VPA, powers the audio circuits and can be connected to a supply
voltage that is different than VCC. For example, VCC can be connected to 3.3 V to minimize digital power drain, and VPA connected
to 5 V in order to achieve maximum power output.
Musical Tone Generator
External audio sources can also be filtered and amplified through
the V-Stamp’s audio system by injecting them into the LINE pin
through a series resistor. If the audio subsystem is not required
in an application (output is taken from the LINE pin instead of the
SP pins), VPA may be left unconnected to further minimize power
consumption. The MUTE# pin may also be used to effectively shut
down the audio subsystem when not in use.
Up to 33 minutes of recorded messages and sound files can be
stored in the V-Stamp for on-demand playback. Recordings are
stored in onboard nonvolatile memory, providing zero-power message storage. Additionally, the V-Stamp can play eight-bit PCM and
ADPCM audio in real time, such as speech and/or sound effects
stored in an external memory or file system.
An integrated, three-voice musical tone generator is capable of generating up to three tones simultaneously over a four-octave range.
Simple tones to attention-getting sounds can be easily created.
4
V-Stamp
RC Systems
voice synthesizer
now you’re talking!
Interfacing the V-Stamp
All communication with the V-Stamp is performed via the built-in
asynchronous serial interface. The serial interface operates with 8
data bits (LSB first), 1 or more stop bits, no parity, and any standard
baud rate between 300 and 115200 bps.
A typical microcontroller interface circuit is shown in Figure 1.
The circuit includes an external programming port, which allows
the V-Stamp to be programmed in-circuit. Data files and firmware
updates can be downloaded from a PC to the V-Stamp through this
port. Note that an external RS-232 transceiver chip will generally be
required, in order to convert the PC’s RS-232 voltage levels to the
V-Stamp’s logic levels.
The CTS# pin should be used to control the flow of data to the VStamp. It is not necessary to check CTS# before transmitting every
byte, however. All data is routed through a high speed 16-byte buffer
within the V-Stamp before being stored in the primary buffer. CTS#
may be checked every eight bytes with no risk of data loss.
V-STAMP
BRS0
BRS1
BRS2
BRS3
RXD
TXD
CTS#
TXD
* INSTALL FOR OPTIONAL
PROGRAMMING PORT
CTS#
CTS
RXD
TXD
Baud Rate
L
L
L
L
L
L
L
L
L
H
H
H
L
L
L
H
H
H
H
L
L
L
L
L
300
L
H
H
L
L
H
H
L
L
H
H
L
H
L
H
L
H
L
H
L
600
1200
2400
4800
9600
19200
Auto-detect
38400
57600
115200
Auto-detect
If the measured bit period is determined to be a valid baud rate,
the V-Stamp will acknowledge lock acquisition by transmitting the
ASCII character “l” (6Ch) on the TXD pin. (Note that nothing will be
transmitted if the baud rate has been programmed for a fixed rate.)
The baud rate will remain locked unless changed with the baud rate
command, or the V-Stamp is reset.
RXD
21
BRS0
The automatic baud rate detection mechanism is enabled when
the BRS0 – BRS3 pins are all at a High logic level. The baud rate is
determined by the shortest High or Low period detected in the input
stream. This period is assumed to be the bit rate of the incoming
data; therefore, it is important that there be at least one isolated
“1” or “0” in the input character. The CR character, 0Dh, is recommended for locking the baud rate. The character is not otherwise
processed by the V-Stamp; it is discarded.
10K *
19
BRS1
Table 2. Baud Rate Options
18
17
16
15
20
BRS2
All other settings
MICRO
VCC
BRS3
*
NOTE The measurement cycle ends when there have been no Highto-Low nor Low-to-High transitions on the RXD pin for 75 ms or
longer. Consequently, the V-Stamp will ignore any data sent to it for
a period of 75 ms after the “lock-on” character has been received.
The CTS# pin is driven High during this time, and the acknowledgment character is not transmitted until the V-Stamp is actually
ready to accept data. See Figure 2.
Figure 1. Serial Interface
Baud Rate Selection
The serial port’s baud rate can be programmed using any of three
methods: pin strapping, auto-detect, and by command. Pin strapping sets the baud rate according to the logic levels present on the
BRS0 – BRS3 pins, as shown in Table 2. Auto-detect enables the
serial port to automatically detect the baud rate of the incoming
data. The baud rate command (described in the DoubleTalk RC8660
Chipset User’s Manual) allows the baud rate to be changed at any
time, effectively overriding the first two methods.
Start bit
LSB
MSB
Baud rate validation (»75 ms)
6Ch
Figure 2. Baud Rate Detection Timing
5
V-Stamp
RC Systems
voice synthesizer
now you’re talking!
Audio Subsystem
ibility, because the pin can be controlled through the V-Stamp’s
serial port using the RC8660’s TS Pin Control command. With the
TS pin’s default setting, the pin will automatically activate the audio
subsystem when required, and shut it down when it is no longer
needed. If an external audio source needs to use the audio subsystem, it can activate it manually by setting the TS pin High with the
3K command.
The V-Stamp’s audio subsystem can directly drive an 8 ohm speaker
with up to one watt of output power at VPA = 5 V. If less power is
needed, the VPA pin can be connected to a lower voltage, such as
3.3 V, which will reduce power consumption. Note, however, that
the power amplifier has been optimized for operation at VPA = 5 V.
When operating at voltages lower than this, it is recommended that
the V-Stamp’s software-controlled volume level (nV command) be
maintained at lower settings in order to avoid distortion in the power
amplifier — which can dramatically increase power dissipation and
power consumption.
A/D Converter
The V-Stamp’s onboard ADC has the following features:
– Four channels, 8-bit resolution (± 2 LSB precision)
– One-shot, continuous, single sweep, and continuous sweep
modes of operation
– Support for external amplification/signal conditioning of all
four ADC channels
The speaker output pins are designed to drive a load differentially.
The benefits of this design compared with a single-ended (groundreferenced) design are many, the most significant being up to four
times greater power output for a given supply voltage, reduced
amplifier power dissipation (higher efficiency), better rejection of
power supply noise, and the elimination of a large DC blocking
capacitor on the output.
In most applications, analog voltages to be converted by the ADC
may be connected directly to the AN0 – AN3 input pins. The minimum and maximum input voltage limits must be observed, however; in many cases this can be accomplished with a simple resistive
divider. Because the CMOS ADC input pin impedances are extremely high, the error introduced by a resistive divider is minimal. It is
also good design practice to include a small capacitor from the AN
pin to ground as a precautionary measure against noise that may be
present on the signal being measured.
Do not attempt to connect a ground-referenced load to either SP
pin directly. Each pin has a DC bias component of VPA / 2 V, which
would result in a high DC current flowing through the load, possibly damaging the load and/or power amplifier. Instead, connect the
load through a DC blocking capacitor. A minimum value of 100 µF
is recommended for 8 ohm loads.
External audio sources may also be filtered and amplified through
the V-Stamp’s audio subsystem by injecting them into the LINE pin
via a series resistor. The total of the resistor and external signal’s
source impedance should be at least several kW in order to avoid
loading the V-Stamp’s signal excessively, and the signal amplitude
must be limited to between 0 V and VCC.
Applications using the ADC for voice recording will require a microphone and preamplifier. The circuit shown in Figure 3 is suitable
for this purpose, as it offers high gain, low cost, and low power consumption (less than 330 µA typ at supply voltages of 3.3 V to 5 V). In
addition, the circuit provides low-pass filtering to prevent undesired
frequencies from reaching the ADC. This circuit should work well
with most any electret condenser microphone.
Power supply consumption can be minimized when the V-Stamp is
not in use by shutting down the audio subsystem with the MUTE#
pin. MUTE# can be connected to a microcontroller’s I/O port pin
for direct control by the application, or it can be connected to the
V-Stamp’s TS pin. Connection to the TS pin offers the greatest flex-
Please refer to the DoubleTalk RC8660 Chipset User’s Manual for
information on programming and using the ADC, as well as how to
record to the RC8660’s recording memory.
VCC
R4 1M
VCC
U1-5
C4 39PF
R1
2K
C1
10UF
R2 10K
C3 1UF
+
R3 2K
3
–
+
4
R6 1M
VCC
1
2
M1
MD9745APZ-F
C2
27NF
R7
1M
1
+
2
R5 5.6K
U1
LMV321M
C6
0.1UF
Figure 3. Microphone Preamp & Filter Circuit
6
C7
0.1UF
TO ADC INPUT PIN
C5
8.2NF
V-Stamp
RC Systems
voice synthesizer
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Electrical Specifications
* WARNING: Stresses greater than those listed under “Absolute
Maximum Ratings” may cause permanent damage to the device.
This is a stress rating only; operation of the device at any condition
above those indicated in the operational sections of these specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
Absolute Maximum Ratings*
Supply voltage, VCC and VPA . . . . . . . . . . . . . . . . – 0.3 V to + 6.5 V
DC input voltage, VI . . . . . . . . . . . . . . . . . . . – 0.3 V to VCC + 0.3 V
Operating temperature, TA. . . . . . . . . . . . . . . . . . . . 0 °C to + 70 °C
Storage temperature, TS . . . . . . . . . . . . . . . . . . – 55 °C to + 125 °C
DC Characteristics
TA = 0 °C to + 70 °C, VCC = 3.3 V / 5 V, VPA = 3.3 V / 5 V, VSS = 0 V
Digital Subsystem
Symbol
Parameter
VIL
Input Voltage, Low
VIH
VIA
Input Voltage, High
Analog Input Voltage (AN0-3)
VHYR
Input Hysterisis, RES#
VOL
Output Voltage, Low
VOH
Output Voltage, High
IIL
Input Load Current
RO
LINE Output Resistance
ICC
Supply Current
VCC = 3.3 ± 0.3 V
Min
Typ
VCC = 5 V ± 0.5 V
Max
Min
Typ
Max
Unit
Test Conditions
– 0.3
0.2VCC
– 0.3
0.2VCC
V
0.7VCC
– 0.3
VCC + 0.3
VCC
0.7VCC
– 0.3
VCC + 0.3
VCC
V
V
0.2
1.8
0.2
1.8
V
0.5
V
IOL = 1 mA
V
IOH = – 1 mA
± 5
µA
VIN = VSS to VCC
10
20
kW
7
1.2
0.8
22
2.5
20
mA
mA
µA
40
mA
0.5
VCC – 0.5
VCC – 0.5
± 4
4
Active
Idle
Standby
10
20
3.8
0.7
0.7
14
1.5
15
Program (Note 1)
4
30
All outputs open;
all inputs = VCC
or VSS
1 Applies during internal programming operations: greeting message, dictionary, recording memory and microcode updates.
Audio Subsystem
Symbol
Parameter
VIL
MUTE# Input Voltage, Low
VIH
MUTE# Input Voltage, High
VOS
SP Output Offset Voltage
PO
SP Output Power (THD < 1%)
IPA
Supply Current
VPA = 3.3 ± 0.3 V
Min
Typ
VPA = 5 V ± 0.5 V
Max
Min
Typ
0.4
1.2
Max
0.4
1.2
5
50
0.3
Unit
Test Conditions
V
V
5
50
1
330
mV
W
RL = 8 W
RL = 8 W
RL = 8 W
RL = ∞
MUTE# = VSS
PO = 1 W
PO = 0.3 W
PO = 0 W
240
3.8
8
4.9
10
mA
mA
mA
Shutdown
0.01
2
0.01
2
µA
VPA may be left unconnected if the output is taken from the LINE pin instead of the SP pins. It is permissible for VPA to be at a different voltage level than VCC.
7
V-Stamp
RC Systems
voice synthesizer
now you’re talking!
AC Characteristics
TA = 0 °C to + 70 °C, VCC = 3.3 V / 5 V, VSS = 0 V
Standby Timing
Symbol
Parameter
tWSBL
VCC = 3.3 ± 0.3 V
VCC = 5 V ± 0.5 V
Min
Min
Max
Max
Unit
STBY# pulse width Low
To enter Standby mode
To exit Standby mode (Sleep Timer invoked; Note 1)
5
5
ms
380
250
ns
1 Monitor the CTS# pin to determine when Standby mode has terminated.
Figure 4. Standby Waveform
Reset Timing
Symbol
tWRS
Parameter
Min
Max
Unit
Notes
Hold RES# Low during power-up. STBY#
must be High no later than 0.5 sec after ­RES#
goes High.
RES# pulse width Low
After power on / VCC stable
1
ms
During operation
3
µs
RES# recovery delay
tDRR
2
ms
Figure 5. Reset Waveform
8
V-Stamp performs internal initialization; all outputs
will be floating. Do not attempt to send data to the
V-Stamp during this period.
V-Stamp
RC Systems
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Mechanical Data

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
9
V-Stamp
RC Systems
voice synthesizer
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Appendix A: Revision History
Revision 01 (April 18, 2007)
Updated DC power specifications. Added 33-minute recording time
option to product offerings.
Specifications
Changed ICC supply current spec in DC Characteristics. Active current has been reduced by approximately 40%.
Ordering Information
VS3950 added to Product Summary table.
Revision 02 (June 27, 2008)
Updated to reflect new Restore mode.
Specifications
Updated STBY# pin description in Table 1.
Revision 03 (January 21, 2009)
Updated to reflect new method of controlling the dataflow of uploads
from recording memory.
Specifications
Updated SUSP# pin description in Table 1.
10
Specifications written in this publication are believed to be accurate, but are not guaranteed to be entirely free of error. RC Systems reserves the right to make
changes in the devices or the device specifications described in this publication without notice. RC Systems advises its customers to obtain the latest version
of device specifications to verify, before placing orders, that the information being relied upon by the customer is current.
In the absence of written agreement to the contrary, RC Systems assumes no liability relating to the sale and/or use of RC Systems products including fitness
for a particular purpose, merchantability, for RC Systems applications assistance, customer’s product design, or infringement of patents or copyrights of third
parties by or arising from use of devices described herein. Nor does RC Systems warrant or represent that any license, either express or implied, is granted
under any patent right, copyright, or other intellectual property right of RC Systems covering or relating to any combination, machine, or process in which such
devices might be or are used. RC Systems products are not intended for use in medical, life saving, or life sustaining applications.
Applications described in this publication are for illustrative purposes only, and RC Systems makes no warranties or representations that the devices described
herein will be suitable for such applications.
1609 England Avenue, Everett, WA 98203
Phone: (425) 355-3800 Fax: (425) 355-1098
www.rcsys.com
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