Linx HT Keyfob Instruction Manual

HT Keyfob
Transmitter
Data Guide

Warning: Some customers may want Linx radio frequency (“RF”)
products to control machinery or devices remotely, including machinery
or devices that can cause death, bodily injuries, and/or property
damage if improperly or inadvertently triggered, particularly in industrial
settings or other applications implicating life-safety concerns (“Life and
Property Safety Situations”).
NO OEM LINX REMOTE CONTROL OR FUNCTION MODULE
SHOULD EVER BE USED IN LIFE AND PROPERTY SAFETY
SITUATIONS. No OEM Linx Remote Control or Function Module
should be modified for Life and Property Safety Situations. Such
modification cannot provide sufficient safety and will void the product’s
regulatory certification and warranty.
Customers may use our (non-Function) Modules, Antenna and
Connectors as part of other systems in Life Safety Situations, but
only with necessary and industry appropriate redundancies and
in compliance with applicable safety standards, including without
limitation, ANSI and NFPA standards. It is solely the responsibility
of any Linx customer who uses one or more of these products to
incorporate appropriate redundancies and safety standards for the Life
and Property Safety Situation application.
Do not use this or any Linx product to trigger an action directly
from the data line or RSSI lines without a protocol or encoder/
decoder to validate the data. Without validation, any signal from
another unrelated transmitter in the environment received by the module
could inadvertently trigger the action.
All RF products are susceptible to RF interference that can prevent
communication. RF products without frequency agility or hopping
implemented are more subject to interference. This module does not
have a frequency hopping protocol built in.
Do not use any Linx product over the limits in this data guide.
Excessive voltage or extended operation at the maximum voltage could
cause product failure. Exceeding the reflow temperature profile could
cause product failure which is not immediately evident.
Do not make any physical or electrical modifications to any Linx
product. This will void the warranty and regulatory and UL certifications
and may cause product failure which is not immediately evident.
!Table of Contents
1 Description
1 Features
1 Applications
1 OEM Congurations
2 Ordering Information
2 Electrical Specications
3 Theory of Operation
4 Setting the Transmitter Address
4 Button Assignments
5 Contention Considerations
5 Battery Replacement
5 Assembly Diagram
6 Compliance Requirements
6 Labeling / Instruction Requirements
8 Typical Applications
10 Resources
11 Notes

– –
1
Description
The Linx HT Keyfob transmitter is ideal
for general-purpose remote control and
command applications. It has been
pre-certified for FCC Part 15, Industry
Canada, and European CE (433MHz
only) compliance, reducing development
costs and time to market. Available in
418 (standard) or 433.92MHz, this stylish
and compact remote has a range of up
to 750 feet when combined with a KH3
module or an LR or LT Series module and
DS Series decoder. The Keyfob can be
configured with 1 to 5 buttons and the
keypad and labeling can be modified to
meet specific customer requirements.
Selectable addressing provides security
and allows the creation of up to 1,022
distinct transmitter-receiver relationships.
The Keyfob is available in black, white,
or translucent colors. The transmission
can be decoded using a matching KH3
Series receiver / decoder, or an LR or LT
Series receiver paired with a decoder IC or
microcontroller. The unit operates from a single 3V CR2032 button cell.
Features
• FCC, IC and CE pre-certified
• Long range
• 1 to 5 buttons
• Compact, stylish package
Applications
• General remote control
• Keyless entry
• Garage / gate openers
• Lighting control
• Home / industrial automation
• Wire elimination
HT Keyfob Transmitter
Data Guide
Revised 10/17/14
2.23"
1.00"
0.45"
1.37"
S4
S2
S1 S3S5
Figure 1: Package Dimensions
Figure 2: Keyfob Button Configurations
OEM Congurations
With a one-time NRE and
minimum order, Linx can
configure the keypad and
label areas. Contact Linx for
details.

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2 3
Ordering Information
Part Number Description
OTX-***-HH-KF#-HT-xxx HT Keyfob Transmitter
EVAL-***-HH-KF-HT HT Keyfob Evaluation Kit
# = Number of Buttons, 1 to 5
*** = 418 (Standard) or 433MHz
xxx = Color (Leave blank for standard black)
WHT = White
CRE = Red
CGY = Gray
Keyfob Electrical Specifications
Parameter Designation Min. Typ. Max. Units Notes
Power Supply
Operating Voltage VCC 2.3 3.0 3.6 VDC
Supply Current lCC 12.6 mA
Power-Down Current lPDN 1.5 µA 1
Transmitter Section
Transmit Frequency Range FC
OTX-418-HH-KF#-HT 418 MHz
OTX-433-HH-KF#-HT 433.92 MHz
Center Frequency Accuracy –8 +8 kHz
Data Rate 2,400 bps
Environmental
Operating Temperature Range 0 +70 °C 1
1. Characterized, but not tested
Electrical Specications
Ordering Information
Figure 3: Ordering Information
Figure 4: Electrical Specifications
Theory of Operation
The HT Keyfob Transmitter combines a high-performance synthesized
transmitter with an on-board encoder IC to form a highly reliable, yet
cost-effective RF remote control transmitter. The transmitter’s synthesized
architecture delivers outstanding stability and frequency accuracy
while minimizing the effects of temperature, antenna port loading
and mismatching. This reduces or eliminates frequency pulling, bit
contraction, and other negative effects common to SAW-based transmitter
architectures, providing a significantly higher level of performance and
reliability.
When a button is pressed on the Keyfob, power is applied to the internal
circuitry and the encoder IC is enabled. The encoder detects the logic
states of the address lines and button data lines. These states are
formatted into a three-word transmission cycle that continues until the
button is released. The encoder data is used to modulate the transmitter,
which, through the antenna, conveys the data into free space. On the
receiver side, a decoder IC or custom microcontroller is used to check
the transmitter’s address bits against the address settings of the receiving
device. If a match is confirmed, the decoder’s outputs are set to replicate
the transmitter’s button states. These outputs can then be used to activate
external circuitry required by the application.
The transmitter is compatible with several Linx receiver products, including
the LR, KH3, LT, and OEM product families. Ranges of up to 750 feet are
possible when the transmitter is combined with the receiver and a good
antenna. Applications operating over shorter distances will also benefit from
the increased link reliability and superior noise immunity provided by the LR
Series receiver.
The DS Series encoder inside the Keyfob transmitter uses a protocol based
on the Holtek®HT640 encoder. It is completely backwards compatible with
older generation transmitters (CMD-KEY#-*** part numbers) and systems
based on the HT658 decoder.

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4 5
Setting the Transmitter Address
The Keyfob allows the selection of one
of 1,022 unique addresses. All keyfobs
are supplied set to the same address.
The address must be changed to avoid
contention with other units or to create
unique relationships. This is accomplished
by cutting the traces. The traces are
accessed by removing the rear cover.
If the trace is intact, the address line is
connected to ground, otherwise it is pulled high. The receiver’s address
must match exactly in order for the units to communicate. Application Note
AN-00300 describes in detail how to set the address to match any of the
receivers offered by Linx. This note can be found in the Support section of
the Linx website, www.linxtechnologies.com.
Button Assignments
The Keyfob is available in five button configurations. Those configurations
and the corresponding switch numbers are shown in Figure 6. The table
shows which encoder data line has been assigned to each switch. When a
button is pressed, the data line goes high, causing the corresponding data
line on the decoder to go high if the address has been learned.
Figure 5: Address Traces
S4
S2
S1 S3S5
S5
S2
S5
S4
S4
S2
S4
S1 S3
S2
Button Data Line
S1 D0
S2 D1
S3 D2
S4 D3
S5 D4
Figure 6: OTX-***-HH-KF#-HT Button Assignments
Contention Considerations
It is important to understand that only one transmitter at a time can be
activated within a reception area. While the transmitted signal consists
of encoded digital data, only one carrier of any particular frequency can
occupy airspace without contention at any given time. If two transmitters
are activated in the same area at the same time, then the signals will
interfere with each other and the decoder will not see a valid transmission,
so it will not take any action.
Battery Replacement
The transmitter utilizes a standard CR2032 lithium
button cell. In normal use, it provides several years of
operation. Access for replacement is accomplished
by gently prying apart the two halves of the Keyfob at
the seam (fingernails or a coin will do). Once the unit is
open, remove the battery by sliding it out from beneath
the retainer.
There may be the risk of explosion if the battery is
replaced by the wrong type. Replace it with the same
type of battery while observing the polarity shown in
Figure 7.
Assembly Diagram
Battery
Figure 7: Battery Access
Figure 8: OTX-***-HH-KF#-HT Assembly
Note: Leaving all of the traces intact (default as shipped) or all cut are not
valid addresses. At least one trace must be different from the rest.
+

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6 7
Labeling / Instruction Requirements
The transmitter has been pre-certified for FCC Part 15 and Industry
Canada license-exempt RSS standards for an intentional radiator. The
433.92MHz version has also been tested for CE compliance for use in
the European Union. The 418MHz version is not legal for use in Europe. It
has already been labeled in accordance with FCC, Industry Canada and
CE regulations. No further labeling of the unit is needed; however, it is
necessary to include the following Instruction to the User statement in the
end product’s instruction manual or insert card.
Europe requires that the final product's instruction manual be provided in
the end user's native language.
INSTRUCTION TO THE USER
This device complies with Part 15 of the FCC Rules and Industry Canada license-
exempt RSS standard(s). Operation of this device is subject to the following two
conditions:
1. This device may not cause harmful interference, and
2. This device must accept any interference received, including interference
that may cause undesired operation.
This equipment has been tested and found to comply with the limits for a Class B
digital device, pursuant to Part 15 of the FCC Rules. These limits are designed to
provide reasonable protection against harmful interference in a residential installation.
This equipment generates, uses and can radiate radio frequency energy and, if not
installed and used in accordance with the instructions, may cause harmful interference
to radio communications. However, there is no guarantee that interference will not
occur in a particular installation. If this equipment does cause harmful interference to
radio or television reception, which can be determined by turning the equipment off
and on, the user is encouraged to try to correct the interference by one or more of the
following measures:
• Reorient or relocate the receiving antenna.
• Increase the separation between the equipment and receiver.
• Connect the equipment into an outlet on a circuit different from that to which the
receiver is connected.
• Consult the dealer or an experienced radio / TV technician for help.
Theuseriscautionedthatchangesandmodicationsmadetotheequipmentwithout
the approval of manufacturer could void the user’s authority to operate this equipment.
Le présent appareil est conforme aux CNR d'Industrie Canada applicables aux
appareils radioexempts de licence. L'exploitation est autorisée aux deux conditions
suivantes : (1) l'appareil ne doit pas produire de brouillage, et (2) l'utilisateur de
l'appareil doit accepter tout brouillage radioélectrique subi, même si le brouillage est
susceptible d'en compromettre le fonctionnement.

– – – –
8 9
Receivers
There are four options for receivers within the Linx
product line. The first option is to use one of the OEM
Function Modules, such as the Relay Module. These
items are also pre-certified and can be immediately
included in a product.
The other options are to use one of the Linx receiver
modules. The signal sent by the Keyfob transmitter
can be received by the LR Series receiver module or
the LT Series transceiver module. These modules can
be connected to the DS Series decoder to decode the
signal, or a custom microcontroller can be programmed
to decode it and take specific action.
The KH3 Series offers a slightly simpler solution by
combining the LR Series receiver and the DS Series
decoder in a single package. This receiver only supports
the Holtek protocol, not the serial protocol.
When a button is pressed on the transmitter, a corresponding line on the
decoder goes high (as long as the addresses match). This can then be
connected to whatever circuitry is required by the application.
Application Note AN-00300 discusses in detail how to set the addresses
on all of the units. Data guides for all of the receivers and the DS Series
decoder can be found on the Linx website, www.linxtechnologies.com.
Typical Applications
Figure 10 shows a typical schematic using the LR Series receiver and the
DS Series decoder.
The decoder has ten address lines that must match the transmitter address
lines. A DIP switch is commonly used to set these, but they can also be
hardwired. As long as the address lines match, when a button on the
transmitter is pressed, a corresponding data line on the decoder (D0–D7)
goes high. These data lines can then be connected to external circuitry to
perform whatever function is required by the application.
P_SEL
1
D0
2
D1
3
D2
4
D3
5
D4
6
D5
7
GND
8
D6
9
D7
10
E/D_SEL
11
D_CFG
12
A_CFG0
13
A_CFG1
14 A0 15
A1 16
A2 17
A3 18
GND 19
VCC 20
A4 21
A5 22
A6 23
A7 24
A8 25
A9 26
TE/DI 27
VT/DO 28
LICAL-EDC-DS001
VCC
GND
GND
GND
GND
D0
D1
D2
D3
D4
D5
D6
D7
VT
100k 100k 100k 100k 100k
100k
100k
100k
100k100k
VCC
GND
VCC
GND
GND
GND
ANTENNA
NC
1
NC
2
NC
3
GND
4
VCC
5
PDN
6
RSSI
7
DATA
8NC 9
NC 10
NC 11
NC 12
NC 13
NC 14
GND15
ANT 16
RXM-xxx-LR
VCC
GND
GND
Figure 9: Linx Receivers
Figure 10: LR Receiver and DS Decoder Schematic

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10 11
Resources
Support
For technical support, product documentation, application notes, regulatory
guidelines and software updates, visit www.linxtechnologies.com
RF Design Services
For customers who need help implementing Linx modules, Linx offers
design services including board layout assistance, programming,
certification advice and packaging design. For more complex RF solutions,
Apex Wireless, a division of Linx Technologies, creates optimized designs
with RF components and firmware selected for the customer’s application.
Call [phone] ([phone] if outside the United States) for
more information.
Antenna Factor Antennas
Linx’s Antenna Factor division has the
industry’s broadest selection of antennas
for a wide variety of applications. For
customers with specialized needs, custom antennas and design services
are available along with simulations of antenna performance to speed
development. Learn more at www.linxtechnologies.com.
by
Notes

Disclaimer
Linx Technologies is continually striving to improve the quality and function of its products. For this reason, we
reserve the right to make changes to our products without notice. The information contained in this Data Guide
is believed to be accurate as of the time of publication. Specifications are based on representative lot samples.
Values may vary from lot-to-lot and are not guaranteed. “Typical” parameters can and do vary over lots and
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