HIGH-PERFORMANCE
MS SERIES
ENCODER
WIRELESS MADE SIMPLE
®
MS SERIES ENCODER DATA GUIDE
DESCRIPTION
MS Series encoders and decoders are
designed for remote control applications.
They allow the status of up to eight buttons
or contacts to be securely transferred via a
wireless link. The large, twenty-four bit
address size makes transmissions highly
unique, minimizing the possibility of
multiple devices having conflicting
addresses. The MS Series decoder allows
the recognition of individual output lines to
be easily defined for each transmitter by
the manufacturer or the user. This enables
the creation of unique user groups and
relationships. The decoder also identifies
and outputs the originating encoder ID for
logging or identification. Housed in a tiny
20-pin SSOP package, MS Series
encoders feature low supply voltage and
current consumption. Selectable baud
rates and latched or momentary outputs
make the MS Series truly versatile.
0.309
(7.85)
0.026
(0.65)
0.207 (5.25)
C
Ro
HS
OMP
IAN
T
L
LICAL-ENC-MS001
YYWWNNN
0.013
(0.32)
0.284
(7.20)
0.007
(0.18)
0.030
(0.75)
Figure 1: Package Dimensions
FEATURES
Secure 2
24
possible addresses
8 data lines
Low 2.0 to 5.5V operating voltage
Low supply current (370µA @ 3V)
Ultra-low 0.1µA standby current
Definable recognition authority
True serial encoding
Excellent noise immunity
Selectable baud rates
No programmer required
Direct serial interface
Small SMD package
Latched or momentary outputs
Encoder ID output by decoder
APPLICATIONS INCLUDE
Keyless Entry
Door and Gate Openers
Security Systems
Remote Device Control
Car Alarms / Starters
Home / Industrial Automation
Remote Status Monitoring
Lighting Control
ORDERING INFORMATION
PART #
DESCRIPTION
LICAL-ENC-MS001
MS Encoder
LICAL-DEC-MS001
MS Decoder
MDEV-LICAL-MS
MS Master Development System
MS encoders are shipped in reels of 1,600
Revised 1/28/08
ELECTRICAL SPECIFICATIONS
Parameter
POWER SUPPLY
Operating Voltage
Supply Current:
At 2.0V V
CC
At 3.0V V
CC
At 5.0V V
CC
Power-Down Current:
At 2.0V V
CC
At 3.0V V
CC
At 5.0V V
CC
ENCODER SECTION
Input Low
Input High
Output Low
Output High
Input Sink Current
Output Drive Current
SEND High to DATA_OUT
ENVIRONMENTAL
Operating Temperature Range
Designation
V
CC
I
CC
Min.
2.0
–
–
–
I
PDN
–
–
–
V
IL
V
IH
V
OL
V
OH
–
–
–
–
0.0
0.8 x V
CC
–
V
CC
- 0.7
–
–
–
-40
0.10
0.10
0.20
–
–
–
–
–
–
1.64
–
0.80
0.85
0.95
0.15 x V
CC
V
CC
0.6
–
25
25
–
+125
µA
µA
µA
V
V
V
V
mA
mA
mS
°C
–
–
–
2
3
–
–
–
–
–
–
Typical
–
240
370
670
Max.
5.5
300
470
780
Units
VDC
µA
µA
µA
Notes
–
1
1
1
RECOMMENDED PAD LAYOUT
The MS Series encoders and decoders are implemented in an industry standard
20-pin Shrink Small Outline Package (20-SSOP). The recommended layout
dimensions are shown below.
0.047
(1.19)
0.016
(0.41)
0.026
(0.65)
0.234 (5.94)
0.328 (8.33)
Figure 2: PCB Layout Dimensions
Table 1: Electrical Specifications
Notes
1. Current consumption with no active loads.
2. For 3V supply, (0.15 x 3.0) = 0.45V max.
3. For 3V supply, (0.8 x 3.0) = 2.4V min.
PRODUCTION CONSIDERATIONS
These surface-mount components are designed to comply with standard reflow
production methods. The recommended reflow profile is shown below and
should not be exceeded, as permanent damage to the part may result.
Lead-Free
Sn
/ Pb
275
ABSOLUTE MAXIMUM RATINGS
Supply Voltage V
CC
Any Input or Output Pin
Max. Current Sourced By Output Pins
Max. Current Sunk By Output Pins
Max. Current Into V
CC
Max. Current Out Of GND
Operating Temperature
Storage Temperature
-0.3
-0.3
to
+6.5
to V
CC
+ 0.3
25
25
250
300
to
+125
to
+150
VDC
VDC
mA
mA
mA
mA
°C
°C
250
225
200
260°C Max
240°C Max
TEMPERATURE (°C)
175
150
125
100
75
50
25
-40
-65
*NOTE*
Exceeding any of the limits of this section may lead to permanent
damage to the device. Furthermore, extended operation at these maximum
ratings may reduce the life of this device.
TIMINGS
Baud Rate
2,400
9,600
19,200
28,800
Page 2
0
0
20
40
60
80
100
120
140
160
180
200
220
240
260
280
300
320
340
360
380
400
420
TIME (SECONDS)
Initial Start-up
72.62
22.42
13.80
11.00
After Valid Rx
38.62
12.42
7.30
6.00
With RX_PDN
(Worst Case)
600+72.62
300+22.42
150+13.80
150+11.00
Figure 3: MS Series Reflow Profile
*CAUTION*
This product is a static-sensitive component. Always wear an ESD
wrist strap and observe proper ESD handling procedures when
working with this device. Failure to observe this precaution may
result in device damage or failure.
Page 3
Table 2: Encoder SEND to Decoder Activation Times (mS)
PIN ASSIGNMENTS
PIN DESCRIPTIONS
Data Lines
1
2
3
4
5
6
7
8
9
10
D6
D7
SEL_BAUD0
SEL_BAUD1
GND
GND
GND
TX_CNTL
DATA_OUT
MODE_IND
LICAL-ENC-MS001
D5
D4
D3
D2
VCC
VCC
D1
D0
SEND
CREATE_ADDR
20
19
18
17
16
15
14
13
12
11
The encoder has eight data lines, D0 through D7. The state of these lines are
captured when the SEND line goes high and encoded for transmission. Upon
successful reception, these states are reproduced on the outputs of the decoder.
SEL_BAUD0 and SEL_BAUD1
These lines are used to
select the baud rate of the
serial data stream. The
state of the lines allows the
selection of one of four
possible baud rates, as
shown in the table.
SEL_BAUD1 SEL_BAUD0 Baud Rate (bps)
0
0
1
1
0
1
0
1
2,400
9,600
19,200
28,800
Table 3: Baud Rate Selection Table
The baud rate must be set before power up. The encoder will not recognize a
change in the baud rate setting after it is on.
GND
These lines are connected to ground.
TX_CNTL
This line goes high when the SEND line goes high, and low when the SEND line
goes low. This can be used to power up an external RF or infrared transmitter
when the encoder is sending data, and power it down when the encoder is
asleep. It can also be used to drive a LED for visual transmit indication.
Figure 4: MS Series Encoder Pin Assignments
Pin Name
D0-D7
SEL_BAUD0
SEL_BAUD1
GND
TX_CNTL
DATA_OUT
MODE_IND
CREATE_ADDR
SEND
V
CC
Pin Number
1, 2, 13, 14, 17-20
3
4
5, 6, 7
8
9
10
11
12
15, 16
I/O
I
I
I
—
O
O
O
I
I
—
Description
Data Input Lines
Baud Rate Selection Line
Baud Rate Selection Line
Ground
External Transmitter Control Line
Serial Data Output
Mode Indicator Output
Create Mode Selection Line
Encoder Send Data Line
Positive Power Supply
DATA_OUT
The encoder will output a serial data stream on this line. This line can directly
interface with all Linx RF transmitter modules.
MODE_IND
This line is activated while the encoder is in Create Mode, allowing the
connection of a LED indicator. The LED will stay on for the entire time the
encoder is in Create Mode, indicating that the encoder is creating a new Code
Word.
CREATE_ADDR
When this line is taken high, the encoder will enter Create Mode and randomly
generate a new Code Word. This word will be continuously randomized while
this line is high, and will be saved as soon as this line is taken low.
SEND
When this line goes high, the encoder will record the states of the data lines,
retrieve the secure Code Word from memory, assemble the packet, and send it
as a serial bit stream out of the DATA_OUT line at the baud rate selected by the
states of the SEL_BAUD lines.
V
CC
This is the positive power supply.
NOTE:
None of the input lines have internal pull-up or pull-down resistors. The input lines must always be in a
known state (either GND or V
CC
) at all times or the operation may not be predictable. The designer must
ensure that the input lines are never floating, either by using external resistors, by tying the lines directly to
GND or V
CC
, or by use of other circuits to control the line state.
Page 4
Page 5
DESIGN CONSIDERATIONS
The Linx MS Series encoders and decoders are designed for remote control
applications. They provide an easy way to securely register button presses or
switch closures over a wireless link. The encoder side turns the status of eight
parallel input lines into a secure, encoded, serial bit-stream output intended for
transmission via an RF or infrared link. Once received, the decoder decodes,
error checks, and analyzes the transmission. If the transmission is authenticated,
the output lines are set to replicate the status of the lines on the encoder.
Prior to the arrival of the Linx MS Series, encoders and decoders typically fell into
one of two categories. First were older generation, low-security devices that
transmitted a fixed address code, usually set manually with a DIP switch. These
address lines frequently caused the user confusion when trying to match a
transmitter to a receiver. Another disadvantage was the possibility that address
information could be captured and later used to compromise the system.
These concerns resulted in the development of a second type of encoder /
decoder that focused on security and utilized encryption to guard against code
cracking or code grabbing. Typically, the encoding of each transmission changes
based on complex mathematical algorithms to prevent someone from replicating
a transmission. These devices gained rapid popularity due to their high security
and the elimination of manual switches; however, they imposed some limitations
of their own. Such devices typically offer a limited number of inputs, the
transmitter and receiver can become desynchronized, and creating relationships
and associations between groups of transmitters and receivers is difficult.
The Linx product line, which includes the MS and HS Series, is the first product
line to offer the best of all worlds. Both series accept up to eight inputs, allowing
a large number of buttons or contacts to be connected. The devices also allow
relationships among multiple encoders and decoders to be easily created.
Security is well provided for. The MS Series uses a random fixed word with 2
24
possible combinations to give a high level of uniqueness and a reasonable level
of security. For applications requiring the highest security, the HS Series, which
employs tri-level, maximum-security encryption, should be considered.
Encoder transmission protocol and methodology is a critical but often overlooked
factor in range and noise immunity. The MS and HS products utilize a true serial
data stream rather than the PWM schemes employed by many competitive
devices. This allows products based on MS or HS devices to achieve superior
range and immunity from interference, edge jitter, and other adverse external
influences.
One of the most important features unique to the MS and HS products is their
ability to establish a unique user identity and profile for the device containing the
encoder. In conventional designs, all encoded transmissions are either
recognized or denied based on the address. In cases where encoder and
decoder addresses match, the state of all data lines is recognized and output.
Linx products uniquely allow a user or manufacturer to define which encoder
inputs will be acknowledged by each decoder. MS series decoders can store up
to 40 system users and unique profiles for each. This allows for an incredible
variety of unique relationships among multiple system components and opens
the door to product features not previously possible.
A PRACTICAL EXAMPLE
Consider this practical example: a three door garage houses Dad’s Corvette,
Mom’s Mercedes, and Son’s Yugo. With most competitive products, any user’s
keyfob could open any garage door as long as the addresses match. In a Linx
MS-based system, the keyfobs could easily be configured to open only certain
doors (guess which one Son gets to open!) The MS Series also allows for
component grouping. Imagine a remote control designed for use in a woodshop.
One button could turn on a vacuum, one an air cleaner, and another a light, yet
another button could then be user configured to turn on all of them with a single
touch. As you can see, the MS Series uniquely combines security and simplicity
with the power to create groups and relationships.
Manual Address Encoders
Advantages
☺
High number of button inputs
Disadvantages
Low-security fixed code
Confusing manual addressing
Low number of addresses
PWM data output
High security vulnerabilities
“Rolling Code” Encoders
Advantages
☺
Highly secure
Eliminates manual address settings
Disadvantages
Low number of button inputs
Encoder and decoder can become unsynchronized
Difficult or impossible to create relationships
Security vulnerabilities
Linx Encoders
Advantages
☺
High number of button inputs
Highly unique (MS)
Highest security available on the market (HS)
Eliminates manual address settings
Allows for associative relationships
Cannot unsynchronize
Serial data output
Encoder ID is output by the decoder
Latched or momentary outputs (MS)
External transmitter and receiver control lines
Disadvantages
Slightly higher cost for some basic applications
Security vulnerabilities (MS only)
Figure 5: Encoder Comparison Table
Page 7
Page 6
ENCODER OPERATION
Upon power up, the encoder will set the baud rate based on the state of the
SEL_BAUD lines, pull the TX_CNTL line low, and go into a low-power sleep
mode. It will remain asleep until either the CREATE_ADDR or the SEND line
goes high. These lines will place the encoder in either Create Mode or Send
Mode as described in the following sections.
Power Up
Set Baud Rate
Pull The TX_CNTL
Line Low
CREATE MODE
The Create Mode allows the generation of a unique address to ensure the
security of transmission and prevent unintentional operation of devices. The MS
encoder allows 16,777,216 (2
24
) possible addresses. Creating the address is
remarkably straightforward.
When the CREATE_ADDR line is pulled high, the encoder randomizes the Code
Word continuously until the CREATE_ADDR line is pulled low. Once the encoder
registers the low line, the Code Word is saved and the encoder will begin to
toggle the MODE_IND line. This will indicate to the user that the encoder is ready
to accept the Control Permissions. Control Permissions are set by activating the
data lines that the user wants the encoder to have the authority to operate.
Pulling the CREATE_ADDR line high again will cause the encoder to save the
Control Permissions and go back to sleep. The Code Word will be sent with
every transmission when the SEND line is pulled high, but the encoder can only
activate the decoder data lines that are authorized by the Control Permissions.
The Code Word is learned by an MS Series decoder by placing the decoder into
Learn Mode and sending a transmission from the encoder. Please refer to the
MS Series Decoder Data Guide for full details.
The CREATE_ADDR line can be tied to a button or contact point accessible by
the user. With a simple press, the user will generate a unique address that
should never again require changing. Some designers may prefer to set a code
during production and not provide for change by the user.
The MODE_IND line allows for the connection of a LED or other device to
indicate to the user that the encoder is in Create Mode. Once the
CREATE_ADDR line goes high and the encoder enters Create Mode, the
MODE_IND line will go high and stay high until the CREATE_ADDR line goes
low. The MODE_IND line is capable of sourcing up to 25mA of current.
Is The
CREATE_ADDR
Line High?
YES
Sleep
NO
Is The
SEND Line
High?
YES
NO
Pull MODE_IND
Line High
Pull The TX_CNTL
Line High
Randomize Code
Word
Get the Data From
the Data Lines
YES
Is the
CREATE_ADDR
Line High?
Compare With
Control
Permissions
NO
Pull MODE_IND
Line Low
Send the Data
Packet
Save Code Word
Is The
SEND Line
High?
NO
YES
Start Toggling
MODE_IND
Pull The TX_CNTL
Line Low
SEND MODE
When the SEND line goes high the encoder will enter Send Mode. The encoder
will pull the TX_CNTL line high to activate the transmitter, record the state of the
data lines, assemble the packet, and send it through the DATA_OUT line. It will
continue doing this for as long as the SEND line is high, updating the state of the
data lines with each transmission. Once SEND is pulled low the encoder will
finish the current transmission, pull TX_CNTL low to deactivate the transmitter,
and go to sleep.
For simple applications that require only a single input, SEND can be tied directly
to the data input line, allowing a single connection. If additional lines are used in
this manner, diodes or dual contact switches will be necessary to prevent voltage
on one data line from activating all of the data lines. The Application Example
section demonstrates the use of diodes for this purpose.
Page 8
Time Out?
YES
NO
Save Control
Permissions
Is the
CREATE_ADDR
Line High?
YES
Pull MODE_IND
Line Low
NO
Poll Data Lines &
Update Control
Permissions
Figure 6: MS Series Encoder Flowchart
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9
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