ETC MDEV-LICAL-MT

HIGH-PERFORMANCE
MT SERIES
TRANSCODER
WIRELESS MADE SIMPLE ®
MT SERIES TRANSCODER DATA GUIDE
Ro
DESCRIPTION
HS
0.309
MT Series transcoders are designed for bi(7.85)
directional remote control applications.
0.207 (5.25)
0.026
Eight status lines can be set up in any
(0.65)
combination of inputs and outputs for the
transfer of button or contact states. An
automatic confirmation indicates that the
transmission was successfully received.
0.284
The large, twenty-four bit address size
(7.20)
0.013
makes transmissions highly unique, (0.32)
minimizing the possibility of conflict
between multiple devices. The MT also
outputs the ID of the originating transcoder
for logging or identification. Recognition of
the individual outputs can be easily
defined for each device by the
manufacturer or end user. This allows the
creation of user groups and relationships.
0.007
0.030
(0.18)
A Serial Interface Engine (SIE) is provided,
(0.75)
which allows configuration and editing of
the device and control of the transcoder by Figure 1: Package Dimensions
an external microprocessor or PC. Housed
in a tiny 20-pin SSOP package, MT Series parts feature low supply voltage, current
consumption, and selectable baud rates.
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LICAL-TRC-MT
YYWWNNN
FEATURES
OMP IAN T
L
APPLICATIONS INCLUDE
Bi-directional control
„ Keyless Entry
Automatic confirmation
„ Door and Gate Openers
„ Security Systems
Secure 224 possible addresses
„ Remote Device Control
8 status lines
„ Car Alarms / Starters
Serial Interface Engine (SIE)
Latched and/or momentary outputs „ Home / Industrial Automation
„ Remote Status Monitoring
Definable recognition authority
„ Paging
Transmitter ID output
Custom data transfer
ORDERING INFORMATION
Device targeting
PART
#
DESCRIPTION
Wide 2.0 to 5.5V operating voltage
LICAL-TRC-MT
MT Transcoder
Low supply current (370µA @ 3V)
MDEV-LICAL-MT
MT Master Development System
True serial encoding
MT transcoders are shipped in reels of 1,600
Selectable baud rates
No programming required
Revised 4/25/08
ELECTRICAL SPECIFICATIONS
Parameter
POWER SUPPLY
Operating Voltage
Supply Current:
At 2.0V VCC
At 3.0V VCC
At 5.0V VCC
Power-Down Current:
At 2.0V VCC
At 3.0V VCC
At 5.0V VCC
TRANSCODER SECTION
Input Low
Input High
Output Low
Output High
Input Sink Current
Output Drive Current
ENVIRONMENTAL
Operating Temperature Range
RECOMMENDED PAD LAYOUT
Designation
Min.
Typical
Max.
Units
Notes
VCC
ICC
2.0
–
5.5
VDC
–
–
–
–
340
500
800
450
700
1,200
µA
µA
µA
1
1
1
–
–
–
0.15
0.20
0.35
1.2
1.5
1.8
µA
µA
µA
–
–
–
VIL
VIH
VOL
VOH
–
–
0.0
0.8 x VCC
–
VCC - 0.7
–
–
–
–
–
–
–
–
0.2 x VCC
VCC
0.6
–
25
25
V
V
V
V
mA
mA
2
3
–
–
–
–
–
-40
–
+85
°C
–
The MT Series transcoders 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)
IPDN
0.026
(0.65)
0.234 (5.94)
0.328 (8.33)
Figure 2: PCB Layout Dimensions
Table 1: Electrical Specifications
PRODUCTION CONSIDERATIONS
Notes
1. Current consumption with no active loads.
2. For 3V supply, (0.2 x 3.0) = 0.6V max.
3. For 3V supply, (0.8 x 3.0) = 2.4V min.
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.
ABSOLUTE MAXIMUM RATINGS
Lead-Free
Sn / Pb
275
-0.3
-0.3
-40
-65
to
+6.5
to VCC + 0.3
25
25
250
300
to
+85
to
+150
VDC
VDC
mA
mA
mA
mA
°C
°C
*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.
260°C Max
250
240°C Max
225
200
TEMPERATURE (°C)
Supply Voltage VCC
Any Input or Output Pin
Max. Current Sourced By Output Pins
Max. Current Sunk By Input Pins
Max. Current Into VCC
Max. Current Out Of GND
Operating Temperature
Storage Temperature
175
150
125
100
75
50
25
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)
Figure 3: MT 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 2
Page 3
PIN ASSIGNMENTS
PIN DESCRIPTIONS
D0 - D7
1
2
3
4
5
6
7
8
9
10
VCC LICAL-TRC-MT GND
D6
D5
D7
D4
CRT/LRN
D3
ENC_SEL
LATCH
SER_IO
SEL_BAUD
CONFIRM
MODE_IND
TR_PDN
D2
TR_SEL
D1
TR_DATA
D0
20
19
18
17
16
15
14
13
12
11
Figure 4: MT Series Transcoder Pin Assignments
Pin Name
I/O
Description
1
—
Positive Power Supply
2, 3, 11-13, 17-19
I/O
Status Control Lines
CRT/LRN
4
I
Create / Learn Mode Activation Line
ENC_SEL
5
I
Encoder Only Select Line
SER_IO
6
I/O
Serial Interface Line
CONFIRM
7
O
Transmission Confirmation Line
TR_PDN
8
O
Transceiver Power Control Line
TR_SEL
9
O
Transceiver Mode Control Line
TR_DATA
10
I/O
Transceiver Data Line
MODE_IND
14
O
Mode Indicator Output
SEL_BAUD
15
I
Baud Rate Selection Line
LATCH
16
I
Set Latched Outputs
GND
20
—
Ground
D0-D7
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 VCC) 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 VCC,
or by use of other circuits to control the line state.
Page 4
CRT/LRN
When this line goes high, the transcoder will enter Learn Mode. If it is held high
for ten seconds, the transcoder will clear its memory. If it goes high while the
ENC_SEL line is high, the transcoder will enter Create Mode. If it goes high while
the SER_IO line is high, the transcoder will enter Serial Mode.
ENC_SEL
If this line is tied high, it will operate as an encoder only. If it is tied low, the
transcoder will default to a decoder until it is set as a transcoder in Create Mode.
SER_IO
This line is used for the Serial Interface Engine, which allows the transcoder to
be programmed by an external device. The transcoder will also use this line to
output the ID of the originating transcoder, status line states, and custom data.
Confirm
Pin Number
VCC
The transcoder has eight status lines, D0 through D7. These lines can be set as
either inputs to record the state of switches or as outputs which will reproduce
switch states upon reception of a valid transmission.
This line will go high when the transcoder receives a confirmation that its
transmission was received correctly.
TR_PDN
This line can be used to automatically control power to an external transceiver.
When waiting for data the transcoder will toggle power to a transceiver at a 10%
on to 90% off ratio. The times are determined by the selected baud rate.
TR_SEL
This line will toggle an external transceiver between transmit mode (high) and
receive mode (low).
TR_DATA
This line will send data to and receive data from an external transceiver.
MODE_IND
This line will switch when a valid transmission is received, when Learn Mode or
Create Mode is entered, and when the memory is cleared. This allows for the
connection of a LED to indicate to the user that these events have taken place.
SEL_BAUD
This line is used to select the baud rate of the serial data stream. If the line is
high, the baud rate will be 28,800bps, if it is low, the baud rate will be 9,600bps.
The baud rate must be set before power up. The transcoder will not recognize
any change in the baud rate setting after it is on.
LATCH
If this line is low, then the data outputs will be momentary (active for as long as
a valid signal is received). If this line is high, the outputs will be latched (when a
signal is received to make a particular data line high, it will remain high until
another transmission is received instructing it to go low) by default, but individual
status lines can be set as latched or momentary through the SIE.
Page 5
OVERVIEW
Many products and applications call for the transfer of button presses or switch
closures across a wireless link. Traditionally, a remote control link has operated
in only one direction, from a transmitter to a receiver. The cost associated with
transceivers has been too high to practically implement in low-cost products.
With the increasing availability of low-cost transceiver solutions, bi-directional
links are now practical and open a new world of opportunity.
In a wireless environment, maintaining the reliability and uniqueness of a
transmitted signal is generally of great importance. In a unidirectional system, IC
devices called encoders and decoders are often utilized to simplify this process.
The encoder side turns the status of a number of input lines into an 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 decoder’s output lines are set to replicate
the status of the encoder’s input lines.
To accommodate bi-directional links, a new type of device has been developed.
Called a transcoder, this device combines a remote control encoder and decoder
into a single device, and is capable of sending commands as well as receiving
them. It is also able to receive an automatic confirmation from the remote side
indicating that its command was received and the appropriate action was taken.
For example, verifying that an automobile’s doors are all closed and have locked,
or a remote valve has actually closed.
TRANSCEIVER POWER CONTROL
The transcoder has the option to control power to an external transceiver through
the TR_PDN line. This line can be connected to a power down or supply line of
a Linx transceiver or a similar input on another transceiver. This allows the
transcoder to power down the transceiver when it is not required, thereby
reducing current consumption and prolonging battery life.
The transcoder pulls the TR_SEL line low to place the transceiver into receive
mode and looks for valid data for 16mS or 32mS, depending on the baud rate. If
data is present on the TR_DATA line, then the transcoder enters Receive Mode.
If no data is present, then the transcoder pulls the TR_PDN line low to power
down the transceiver and goes to sleep for 150mS or 295mS. The “off” time is
approximately nine times the “on” time, resulting in a 10% duty cycle, greatly
reducing the transceiver’s current consumption. However, there may be a lag
time from when the transmitting transcoder activates to when the receiving
transcoder responds. The transcoder enters Receive Mode when it sees a valid
packet, so there would only be a lag for the first packet.
This cycle continues until data is received placing the transcoder into Receive
Mode, until a status input line is taken high placing it into Transmit Mode, or the
CRT/LRN line is taken high placing it into Serial, Learn, or Create Modes. If a
faster response time is desired, then the TR_PDN line can be left disconnected.
OPERATION WITH THE MS SERIES
The Linx MT Series is a revolutionary transcoder product designed for wireless
remote control applications. The same device can be used as an encoder,
decoder, or transcoder and is ideal for both uni- and bidirectional applications
and even mixtures of the two. The MT Series is easily implemented, making it
ideal for even the most basic applications, but its rich feature set also allows it to
meet the needs of far more complex applications. These features include the
ability to identify the originating transmitter, establish user permissions, select
output latch modes on a “per pin” basis, and a powerful serial interface that
allows control and information exchange with external microcontrollers or a PC.
The MT Series transcoders are fully compatible with the MS Series encoders
and decoders. Tying the ENC_SEL line high makes the transcoder operate just
like an MS Series encoder. Tying this line low enables it to become an MS
decoder or a transcoder, depending on how it is set-up. This is described in detail
in the Transcoder Operation section.
Consider a brief example of how just one of the MT’s innovative features could
be used to transform a relatively simple application, the common garage door
opener. In competitive devices, encoded transmissions are generally either
recognized or denied based on the address. If the addresses match, the state of
all data lines will be recognized and output. The MT Series allows a user or
manufacturer to establish a user identity and profile that determines which inputs
will be acknowledged. Let’s apply this capability practically to our 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 MT-based system, each individual
keyfob could easily be configured to open only certain doors (guess which one
Son gets to open!)
The main advantage offered by the MT over the MS is the serial interface. This
allows a number of advanced options to be realized. Some other advantages
are:
As you review this data guide keep in mind that it seeks to cover the full scope
of the MT’s capabilities. The implementation for a simple one button remote will
be different than a powerful targeted control, command, or status network. While
it is unlikely that all of the features of this part will be utilized at any one time, their
availability provides great design flexibility and opens up many new opportunities
for product innovation.
Page 6
There are two important issues of note when using the transcoders with the MS
Series. First, only two of the MS baud rates are supported by the MT; 9,600bps
and 28,800bps. Second, the MS Series will not respond to the advanced
features of the MT, like the custom data and Targeted Device Addressing.
• More users (60 vs. 40)
• Automatic confirmation
• The lower duty cycle (25% vs. 50%) of the MT Series allows for greater range
in countries like the United States that average transmitter output power over
time.
• The serial output on every packet instead of just once per receive session.
• Allows existing receive stations using the MS Series decoder to be upgraded to
take advantage of the advanced features without having to upgrade existing
transmitter stations based on the MS Series encoder.
• Mixed MS / MT-based systems that allow cost savings for units that only require
unidirectional operation while other units require bidirectional operation.
Page 7
Set-Up
Default
(From Factory)
Defined
(After Create Mode)
Power-Up State
Mode
Description
Default Decoder Mode All status lines are outputs
Default Encoder Mode All status lines are inputs, default address
ENC_SEL is Low
Defined Encoder Mode Encoder only using defined inputs and address
ENC_SEL is High
ENC_SEL is High
Transcoder using defined inputs, outputs, and
address
Transcoder Mode
User Access
Open
(From Factory)
Description
Any valid packet activates outputs
Locked
Only authorized users are allowed
(After Learn Mode)
Open
Any valid packet activates outputs
(From Factory)
Locked
Only authorized users are allowed
(After Learn Mode)
Reply
0x00 - 0x41 - 0x43 - 0x4B - 0xFF
ENC_SEL is Low
Command
925.00
0x00 - 0xFF - 0x52 - 0x73 - 0x74 - 0x4D - 0x54 - 0xFF
890.00
Table 2: MT Series Mode Definitions
Definition
870.00
Page 8
Restore Default
5.29
900.00
• Prior to Learn Mode, any valid MS or MT style packet will activate the status line
outputs.
Table 3: MT Series Transcoder Restore Default Serial Interface Engine Command
4.00
880.00
In summary, there are two key points in the initial operation of the transcoders:
• Prior to Create Mode, all of the status lines will be either inputs or outputs
depending on the state of the ENC_SEL line when the transcoder is powered
on.
SER_IO = Output
1.07
870.00
The transcoder then sets the baud rate according to the state of the SEL_BAUD
line and goes to sleep until an action on one of its inputs places it into another
mode.
SER_IO = Input
8.30
1.73
If the transcoder has been previously set up, through creating an address and
learning users, then the saved settings are applied and the transcoder enters the
appropriate mode based on the state of the ENC_SEL line.
Min Ready Max Ready Receive Cmd Process Cmd Reply Wait Transmit Reply Finish Process Min Total Time Max Total Time
33.00
4.00
Table 2 shows the different modes and how they are entered.
Definition
0.08
1.07
If the ENC_SEL line is low, the transcoder enters Transcoder Mode and uses
both the inputs and outputs as well as the defined address. In this mode, it can
send commands as well as receive commands. As above, the User Access is
open until a user is learned into memory.
2.80
Once an address has been created, the transcoder enters a Defined set-up. The
state of the ENC_SEL on power-up also determines the mode of operation in this
set-up. If the ENC_SEL line is high, the transcoder enters Defined Encoder
Mode. The process of creating an address also defines which status lines are
inputs and which are outputs. In this mode, the transcoder acts as an encoder
only using just the defined inputs and the address that was created.
17.00
The User Access can be locked simply by learning a user. From this point on, it
requires that the transmission have a valid, learned address before it will
respond. Only a Restore Default commend sent on the serial interface will place
the transcoder back into Default Decoder Mode. This command removes all
existing settings and restores the transcoder to the factory default condition.
0.08
If the ENC_SEL line is low, then the transcoder enters Default Decoder Mode
and acts like a decoder only. It pulls the TR_SEL line low to set the transceiver
into receive mode and makes all of its status lines outputs. At this point, the User
Access is open, so the transcoder accepts all valid transmissions, regardless of
address. This allows the designer to set up an external database for learned
users and control permissions. The designer is free to set up a system of their
choosing. External parts can be used with the transcoder to give the end product
more memory to increase the number of users and more processing speed have
a faster response time when scanning through the user list. In this mode, the
transcoders become a data pipe around which a designer can create a larger,
more complicated system than can be implemented with the transcoders alone.
Restore Default
(9,600bps)
Restore Default
(28,800bps)
When the transcoder powers on for the first time, it is in a default set-up. When
in this mode, the transcoder looks at the state of the ENC_SEL line on powerup. If the line is high, then the transcoder enters Default Encoder Mode and acts
like an encoder only. It pulls the TR_SEL line high to set the transceiver into
transmit mode and makes all of its status lines inputs. It will use a default
address that is set at the factory.
Table 4: MT Series Transcoder Serial Interface Engine Timings (mS)
TRANSCODER OPERATION
Page 9
CREATE MODE
Create Mode allows the generation of a unique address to ensure the
uniqueness of a transmission and prevent unintentional operation of devices.
The MT Series transcoder allows for the creation of 16,777,216 (224) possible
addresses. The assignment of the status lines as inputs or outputs also occurs
in this mode.
Create Mode is entered by pulling the CRT/LRN line high while the ENC_SEL
line is high. The address is randomized for as long as the CRT/LRN line is high
(the ENC_SEL line is not checked again once the process is begun). Once the
line is pulled low, the resulting address is saved in memory and the transcoder
is ready to accept the status line assignments. Each line that is to be an input
should be pulled high. Any lines not taken high are set as outputs. There is no
requirement for the order in which the lines are activated or the time between
activations as long as all of the desired lines are activated within the time out
period. The transcoder saves the assignments and goes to sleep when the
CRT/LRN line is taken high again or when it times out after 15 seconds.
LEARN MODE
In order for the transcoder to accept transmissions from a specific transcoder, it
must first learn that transcoder’s address. This is done by taking the CRT/LRN
line high then low while the ENC_SEL line is low to place the transcoder into
Learn Mode. Once in Learn Mode, the MODE_IND line starts switching, allowing
for connection of a LED to provide visual indication that the transcoder is ready
to accept a new address. This continues until the CRT/LRN line goes high again
or until a time-out after 15 seconds.
The transcoder looks for a valid transmission from another transcoder and
records the received address. It also records the status line that was activated in
the Control Permissions. Each status line on the transmitting side that will be
authorized to control the receiving transcoder needs to be activated. The
receiving transcoder updates the Control Permissions with each valid packet that
contains a new active status line. It is not necessary to hold all of the desired
status lines on the transmitting side high at the same time, simply press each one
that is to be authorized within the time out period. When the CRT/LRN line is
taken high again or the transcoder times-out after 15 seconds, the recorded
address and Control Permissions are saved in memory and the transcoder
returns to sleep.
The MT Series transcoder can store up to sixty unique addresses in its memory.
If a transcoder is re-learned, its permissions are overwritten. The transcoder
does not create a second instance of the same address. If a new transcoder is
learned while the memory is full, then the transcoder writes the new address over
the first address in memory. It flashes the MODE_IND line five times to indicate
that the memory is full and the next address learned will overwrite the first. All of
the learned addresses are retained if power is removed from the transcoder.
If the CRT/LRN line is held high for ten seconds while the ENC_SEL line is low,
then the transcoder erases all of the stored addresses from memory. The
MODE_IND line goes high for as long as the CRT/LRN line is high, but after the
ten seconds it goes low. Once the CRT/LRN line is pulled low again, the
MODE_IND line goes high for two seconds to indicate that the memory has been
cleared.
Page 10
TRANSMIT MODE
When any of the status lines that are set as inputs go high, the transcoder enters
Transmit Mode. It pulls the TR_PDN line high to activate the transceiver, pulls
the TR_SEL line high to place the transceiver into transmit mode, records the
states of the status lines, assembles the packet, and sends it through the
TR_DATA line. The transcoder then pulls the TR_SEL line low to place the
transceiver into receive mode and looks for a confirmation from the remote
transcoder. If a valid confirmation is received, then the transcoder pulls the
CONFIRM line high, otherwise it checks to see if any status line inputs are high.
The transcoder continues this for as long as any of the status line inputs are high,
updating the states of the status lines with each transmission. Once all of the
input lines are pulled low, the transcoder finishes the current transmission, pulls
CONFIRM and TR_PDN low to deactivate the transceiver, and goes to sleep.
The MT has the ability to control the status line byte through the SIE. An external
microcontroller or PC can be used to write the desired input states and a packet
counter into the transcoder. The transcoder uses this byte instead of looking at
the status line inputs, sends the specified number of packets, then goes to sleep.
This is subject to the I/O settings, so lines set as outputs cannot be set high.
RECEIVE MODE
When a rising edge is seen on the TR_DATA line, the transcoder enters Receive
Mode. It then looks for a valid packet, meaning that there are no errors and that
the received address matches one that is saved in memory. In addition, if
Targeted Device Addressing is enabled, then the received targeted address
must match the transcoder’s local address. If no valid data is received within 16
or 32mS (dependent on the selected baud rate) then Receive Mode is exited. If
there is a match, then the transcoder pulls the MODE_IND line high as an
indication that a valid signal was received. It compares the received commands
to the Control Permissions associated with the transcoder that sent the signal,
and reproduces the states of the authorized status lines on the originating
transcoder on its own status lines. If Confirmation is enabled, the transcoder then
pulls the TR_SEL line high to place the transceiver into transmit mode and sends
a confirmation to the originating transcoder. It also outputs the ID of the
originating transcoder, a Command Byte that represents the states of the status
lines, and a custom data byte programmed by the user. It then looks for the next
valid data packet. If, at any time, an error or an unknown address is detected,
then the transcoder ignores the packet and looks for the next one. If the 131mS
timer runs out before any valid packets are received, then the transcoder goes
back to sleep.
TX ID
The transcoder outputs an eight-bit binary number on the SER_IO line to identify
which learned transcoder sent the transmission. The number normally
corresponds to the order in which the transcoder was learned, so the first
transcoder learned will get number ‘1’, the second will get number ‘2’, and so on.
An exception arises when the memory is full, in which case the first numbers are
overwritten as described in the Learn Mode section. An exception also arises if
the serial interface is used to write an address to a specific location in memory.
The TX ID is output with the Status and Custom Data bytes after every valid
packet that is received, as described in the Serial Output section.
Page 11
LATCH MODE
The transcoder has two output options based on the state of the LATCH line. If
the line is low, then all of the status line outputs will be momentary, meaning that
they will only be high for as long as a valid signal is received. Once the signal
stops and the transcoder times out, the lines are pulled low.
If the LATCH line is high, then the transcoder will use a Latch Mask on the
outputs. By default, all of the status line outputs are set to latch, so the
transcoder will pull a data line high upon reception of a valid signal and hold it
high until the signal is received a second time, at which point the transcoder will
pull it low. The transcoder must see a break and time out of Receive Mode
between valid transmissions before it will toggle the outputs.
MODE ENTRY TIMINGS
The transcoder may enter the desired mode within minimum timings shown in
the figure below. However, if the transcoder is in another mode at the time the
CRT/LRN line goes high, then it could take longer for the transcoder to recognize
the trigger. For example, Receive Mode at 9,600bps can take 32mS to exit. For
this reason, it is recommended to increase the time to ensure that the transcoder
will enter the correct mode. Typical times are shown in the figure, but may be
adjusted according to the application.
Create Mode
CRT/LRN
The Latch Mask can be changed through the SIE so that individual status lines
can be set as latched or momentary. The Serial Mode section has more
information on the SIE.
TARGETED DEVICE ADDRESSING
One of the powerful features of the MT is Targeted Device Addressing. This is
the ability to target the specific device that is to acknowledge the transmission.
This is accomplished by entering the address of the target device through the
SIE. For example, if a master controller needs Device 10 to activate, a
microcontroller or PC can be used to program the address of Device 10 into the
transcoder in the master controller. The transcoder will then broadcast that
address with the commands, and only Device 10 will respond. This enables
many types of master-slave, peer-to-peer, and even basic networking systems
to be quickly realized. The simple command set and open architecture allow
such systems to be implemented in many ways. Application Note AN-00157
goes into this feature in more detail.
Targeted Device Addressing only needs to be enabled on the transmitting side.
The receiving side identifies the packet as a targeted packet and responds
appropriately. This option is disabled by default.
This feature is useful for sending an 8-bit A/D value from a sensor, custom
command codes, or an additional user-defined ID for additional proprietary
system authentication. There are no restrictions on the 8-bit value, though 0xFF
is not recommended for use since that is the default value with no data.
The Custom Data is output with the Status and TX ID bytes, as described in the
Serial Output section.
120µS min
(35mS typ)
CRT/LRN
ENC_SEL
ENC_SEL
t 120µS min
Time t does not matter as
(35mS typ)
long as ENC_SEL goes
high before CRT/LRN.
Figure 5: MT Series Mode Entry Timings
D0 - D7
TR_PDN
TR_SEL
TR_DATA
Output
Input
Data Out
Output
Confirm
CONFIRM
80µS
20µS
765µS
CUSTOM DATA TRANSMISSION
The MT Series offers the option of sending one byte of custom data with the
command packet. The custom byte is entered into the transcoder through the
SIE using the Read and Write Custom Data Value commands. This option is
enabled or disabled using the Enable and Disable Custom Data commands. The
custom data byte is output on the receiving end with the TX ID and Status bytes.
Custom Data Transmission only needs to be enabled on the transmitting side.
The receiving side identifies the packet as containing custom data and outputs
the byte. This option is disabled by default and the receiving transcoder outputs
a value of 0xFF for the custom byte.
Learn Mode
10µS
Depends on
features and
baud rate
560µS
32µS
Depends 3.4 to 8.0mS
on receiver (depends on
baud rate)
Figure 6: MT Series Transmit Timings
TR_DATA Data In
Input
Confirm
Output
Input
MODE_IND
SER_IO
TR_SEL
D0 - D7
5µS 15µS
520µS to 2.3mS
(depends on user
placement in memory)
15µS
640µS
50 to 75µS 1.39 to 6.25mS
(depends on (depends mode
Latch Mask) and baud rate)
10µS
3.4 to 8.0mS
(depends on
baud rate)
Figure 7: MT Series Receive Timings
Page 12
Page 13
SERIAL OUTPUT
SERIAL MODE
Upon reception of every valid packet, the transcoder outputs a serial data stream
containing information about the transmission. The information takes two forms
depending on the User Access setting.
If the User Access is set to open, then the serial output consists of a start byte,
the three byte address of the transmitting device, a status line byte, a custom
data byte, and a stop byte. The start byte is 0x00 and the stop byte is 0xFF.
00
SER_IO
start b0
b1
b2
b3
ADR 1
b4
ADR 2
b5
b6
ADR 3
The SIE consists of twenty commands. The transcoder outputs an
acknowledgement once it has received each command, and then a response of
up to four additional bytes if required by the command.
STATUS CUSTOM FF
b7 stop start b0
b1
b2
b3
b4
b5
b6
b7 stop
Figure 8: MT Series Transcoder Open Access Serial Output
If the User Access is set to locked, then the serial output consists of a start byte,
TX ID byte, status line byte, custom data byte, and a stop byte. The start byte is
0x00 and the stop byte is 0xFF.
00
SER_IO
TX ID
One of the most powerful features of the MT Series is its Serial Interface Engine
(SIE). The SIE allows the user to monitor and control the device configuration
settings through an automated system or PC rather than manually through the
hardware lines. While serial programming is not required for basic operation, it
enables the advanced features offered by the MT, such as Targeted Device
Addressing and Custom Data transmissions.
Serial Mode is entered by taking the CRT/LRN line high while the SER_IO line
is high. The MODE_IND line goes high for as long as the SER_IO line is an
output, allowing it to be used with RS-232 style handshaking. Each byte is sent
LSB first with one start bit, one stop bit, and no parity at the baud rate determined
by the SEL_BAUD line. After the last command byte is received, there will be a
1mS pause while the SER_IO line is changed to an output, then a 4mS pause
while the transcoder processes the command. Then it outputs the
acknowledgement and a response if appropriate. The SER_IO line is changed to
an input as soon as the MODE_IND line drops after the acknowledgement is
sent. The figure below shows the order and timing of the serial interface.
STATUS CUSTOM FF
CRT/LRN (INPUT)
MODE_IND (OUTPUT)
start b0
b1
b2
b3
b4
b5
b6
b7 stop start b0
b1
b2
b3
b4
b5
b6
b7 stop
SER_IO = INPUT
Figure 9: MT Series Transcoder Locked Access Serial Output
The status line byte reflects the states of the status lines, ‘1’ for high and ‘0’ for
low. This represents the current logic states of the outputs, not the command that
was received, so that the states of latched lines are correctly represented. Line
D0 corresponds to bit b0 in the byte, D1 corresponds to b1, and so forth. This
allows applications that use an embedded microcontroller to read the transmitted
commands without having to monitor eight hardware lines.
The TXID and Custom Data bytes are described in their own sections.
The bytes are output asynchronously least significant bit first with one start bit,
one stop bit, and no parity at the baud rate determined by the SEL_BAUD line.
During normal operation, the SER_IO line is an input, becoming an output only
when sending the data stream or responding to a serial command. These are
described more in the Serial Interface section. Application Note AN-00157 shows
some example software to read the TX ID and associate it with a particular
transcoder.
This feature is useful in applications that need to track and record activation
attempts. The transcoder validates that the command is from an authorized
transmitter and an external microcontroller or PC can record the TX ID and
status line activation and time into a log. The Custom byte can also be used as
an additional validation or to send a sensor reading that also needs to be logged.
Page 14
SER_IO = OUTPUT
Command
SER_IO (INPUT/OUTPUT)
00
C
C
C
b3
b4
b5
b6
C
Acknowledge/Response
C
C
FF 1mS
4mS
00
A
A
b4
b5
b6
A
R
R
R
R
FF
t1 t2
start b0
b1
b2
b7 stop start b0
b1
b2
b3
b7 stop
Figure 10: MT Series Transcoder Serial Programming
Time t1 in the figure above does not have to be any specific time, just so long as
the SER_IO line goes high before the CRT/LRN line. Time t2 should be greater
than 120µS (typical of 35mS, see the Mode Entry Timings section) to ensure that
the transcoder goes into Serial Mode. There is not a maximum time specified.
Once in Serial Mode, the transcoder waits for the start byte (0x00) of the serial
command.
The timings associated with each command and the transcoder’s response are
listed in Tables 7 (9,600bps) and 8 (28,800bps).
To send consecutive commands, keep the CRT/LRN line high and take the
SER_IO line high within 50µS of the MODE_IND line going low.
It should be noted that all of the settings are written into non-volatile memory, so
they will be retained if power is removed from the chip. This includes all values,
such as custom byte and target address, as well as the enabled / disabled states.
Page 15
SERIAL INTERFACE CONNECTIONS
There are ten functions using the Serial Interface Engine (SIE). Each function
has the ability to read the current setting from the MT or write new information to
the specified configuration setting.
Next User ID
Reads and writes the next available ID location, which will be
given to the next user manually learned into the system.
Specific User
Reads and writes the 24-bit address and status line configuration
for a specific user learned into the system. If a device in the
system is lost or stolen, that specific device can be removed from
the system and replaced with a new one without having to erase
the memory and re-learn all of the other devices in the system.
To remove an existing user, write 0xFF into the address and
status line values. 0xFF should not be used as a learned user.
Target Address
Reads and writes the local device’s 24-bit target address. This
allows a user to communicate directly with a specified target
device and not with any other devices even though they may have
been authorized for communication.
Custom Data Value
Reads and writes a single byte that is sent when Custom Data is
enabled. If enabled, the byte will be sent with each packet, and
then output on the SER_IO line of the receiving device along with
the TX ID value and the status line value.
Latch Mask
Reads and writes the Latch Mask for the status line outputs. This
allows each status line to be individually set as momentary or
latched.
Status Value
Reads the current state of the transcoder’s status line outputs.
Writes the value of the status line inputs to be sent (subject to I/O
mask) and the number of packets to send.
Confirmation EN
Reads and writes the device’s confirmation enable setting. When
enabled, the receiving transcoder will immediately transmit a
confirmation packet back to the originating transcoder. The
originating transcoder will validate the confirmation and then
activate its CONFIRM line. If the confirmation is not necessary or
the user wants to free the air of additional transmissions,
confirmation can be disabled and the receiving device will not
transmit a confirmation packet.
Targeting EN
Reads and writes the device’s target enable setting. This enables
or disables the option for the transcoder to send a targeted data
packet.
Custom Data EN
Reads and writes the transcoder’s custom data setting. This
enables or disables the option for the transcoder to send a custom
data byte with each transmission.
Page 16
USB Type B
Connector
GND
DAT+
GSHD
Reads and writes the device’s local 24-bit address and status line
configuration. This allows the option to program all devices with
the same address and status line configuration, or increment the
address to utilize the full range of addresses.
GSHD
Local Settings
Description
6
Command
The serial interface on the MT Series can be connected to any device capable
of serial communication, including microcontrollers, RS-232 drivers, and
computers. The figure below gives an example of connecting the MT to the Linx
QS Series USB module for connection to a computer.
5
SERIAL INTERFACE COMMAND SET DEFINITIONS
DAT 5V
4
3
2
1
GND
VCC
1
2
3
4
5
6
7
8
USBDP
USBDM
GND
VCC
SUSP_IND
RX_IND
TX_IND
485_TX
RI
DCD
DSR
DATA_IN
DATA_OUT
RTS
CTS
DTR
16
15
14
13
12
11
10
9
1
V+
8
2
7
3
6
4
NC
GND
NC
5
MAX4544
SDM-USB-QS
VCC
1
2
3
4
5
6
7
8
9
10
VCC
D6
D7
CRT/LRN
ENC_SEL
SER_IO
CONFIRM
TR_PDN
TR_SEL
TR_DATA
GND
D5
D4
D3
LATCH
SEL_BAUD
MODE_IND
D2
D1
D0
20
19
18
17
16
15
14
13
12
11
LICAL-TRC-MT
Figure 11: MT Series Transcoder Serial Interface to a PC
The USB module follows the RS-232 convention of using separate lines for data
input and data output while the transcoder has a single line for all data. This
requires a switch to alternatively connect the transcoder’s SER_IO line to the
data lines on the module.
The RTS line is used to throw the switch as well as to activate the CRT/LRN line
placing the transcoder into Serial Mode. This gives the PC the ability to control
when communication is initiated.
The MODE_IND line will go high when the transcoder is prepared to send data,
so the CTS line on the USB module is used to monitor the MODE_IND line. This
allows the computer to know when to throw the switch and look for data from the
transcoder.
One point of note is that voltage translation may be necessary if the 5V USB
module is used to communicate with a transcoder operating at 3V. There are
many components and methods for implementing level shifting, so it is up to the
designer to determine the best solution for the product.
Page 17
On
On
Off
Off
On
On
Off
Off
Off
On
On
On
On
Off
Off
Off
Off
On
On
Off
Off
Off
Off
Off
Off
Off
Off
9,600
28,800
9,600
28,800
9,600
28,800
9,600
28,800
9,600
28,800
9,600
12.9
27.2
12.9
23.8
11.6
24.4
11.9
21.3
11.0
23.0
11.3
20.0
15.1
7.0
13.8
7.0
13.8
5.7
11.0
5.7
11.0
5.0
9.6
5.0
9.6
172.6
343.1
172.0
341.8
172.0
341.8
170.7
339.0
170.7
339.0
170.0
337.6
170.0
337.6
23.3
21.6
26.6
20.9
22.4
20.9
25.6
19.8
20.3
19.3
23.2
19.1
19.1
18.6
22.0
TX Data Duty
Cycle (%)
Off
Off
On
28,800
25
7.6
343.1
21.3
Max Activation
Time (mS)
Off
Off
On
9,600
13.4
15.1
172.6
Min Activation
Time (mS)
On
Off
On
28,800
28.6
7.6
Packet Time
(mS)
On
On
On
9,600
13.6
Baud Rate
(bps)
Off
On
On
28,800
Custom Data Targeted Device
Transmission
Addressing
Off
On
On
Confirmation
On
On
Reply
On
Minimum Activation time without Transceiver Power Control
Maximum Activation time with Transceiver Power Control
Command
Table 6: MT Series Transcoder Activation Times and Transmitted Packet Duty Cycle
Definition
Read Local Settings
0x00 - 0x01 - 0x00 - 0x00 - 0x00 - 0x00 - 0x00 - 0xFF
0x00 - 0x41 - 0x43 - 0x4B - A1 - A2 - A3 - IOs - 0xFF
0x00 - 0x41 - 0x43 - 0x4B - 0xFF
Write Local Settings
0x00 - 0x02 - A1 - A2 - A3 - IOs - 0x00 - 0xFF
Read Next User ID
0x00 - 0x11 - 0x00 - 0x00 - 0x00 - 0x00 - 0x00 - 0xFF
0x00 - 0x41 - 0x43 - 0x4B - ID - 0xFF
Write Next User ID
0x00 - 0x12 - ID - 0x00 - 0x00 - 0x00 - 0x00 - 0xFF
0x00 - 0x41 - 0x43 - 0x4B - 0xFF
Read Specific User
0x00 - 0x21 - ID - 0x00 - 0x00 - 0x00 - 0x00 - 0xFF
0x00 - 0x41 - 0x43 - 0x4B - A1 - A2 - A3 - CP - 0xFF
0x00 - 0x22 - A1 - A2 - A3 - CP - ID - 0xFF
0x00 - 0x41 - 0x43 - 0x4B - 0xFF
Write Specific User
0x00 - 0x31 - 0x00 - 0x00 - 0x00 - 0x00 - 0x00 - 0xFF
0x00 - 0x41 - 0x43 - 0x4B - A1 - A2 - A3 - 0xFF
Read Target Address
Write Target Address
0x00 - 0x41 - 0x43 - 0x4B - 0xFF
0x00 - 0x32 - A1 - A2 - A3 - 0x00 - 0x00 - 0xFF
Read Custom Data Value
0x00 - 0x41 - 0x00 - 0x00 - 0x00 - 0x00 - 0x00 - 0xFF
0x00 - 0x41 - 0x43 - 0x4B - Data - 0xFF
Write Custom Data Value
0x00 - 0x42 - Data - 0x00 - 0x00 - 0x00 - 0x00 - 0xFF
0x00 - 0x41 - 0x43 - 0x4B - 0xFF
0x00 - 0x41 - 0x43 - 0x4B - Mask - 0xFF
Read Latch Mask Value
0x00 - 0x51 - 0x00 - 0x00 - 0x00 - 0x00 - 0x00 - 0xFF
0x00 - 0x41 - 0x43 - 0x4B - 0xFF
Write Latch Mask Value
0x00 - 0x52 - Mask - 0x00 - 0x00 - 0x00 - 0x00 - 0xFF
Read Status Outputs
0x00 - 0x61 - 0x00 - 0x00 - 0x00 - 0x00 - 0x00 - 0xFF
0x00 - 0x41 - 0x43 - 0x4B - Outputs - 0xFF
Write Status Inputs
0x00 - 0x62 - Status - Packets - 0x00 - 0x00 - 0x00 - 0xFF
0x00 - 0x41 - 0x43 - 0x4B - 0xFF
Read Confirmation EN
0x00 - 0x71 - 0x00 - 0x00 - 0x00 - 0x00 - 0x00 - 0xFF
0x00 - 0x41 - 0x43 - 0x4B - VAL - 0xFF
0x00 - 0x41 - 0x43 - 0x4B - 0xFF
Write Confirmation EN
0x00 - 0x72 - VAL - 0x00 - 0x00 - 0x00 - 0x00 - 0xFF
0x00 - 0x41 - 0x43 - 0x4B - VAL - 0xFF
Read Device Targeting EN
0x00 - 0x81 - 0x00 - 0x00 - 0x00 - 0x00 - 0x00 - 0xFF
Write Device Targeting EN
0x00 - 0x82 - VAL - 0x00 - 0x00 - 0x00 - 0x00 - 0xFF
0x00 - 0x41 - 0x43 - 0x4B - 0xFF
Read Custom Data EN
0x00 - 0x91 - 0x00 - 0x00 - 0x00 - 0x00 - 0x00 - 0xFF
0x00 - 0x41 - 0x43 - 0x4B - VAL - 0xFF
Write Custom Data EN
0x00 - 0x92 - VAL - 0x00 - 0x00 - 0x00 - 0x00 - 0xFF
0x00 - 0x41 - 0x43 - 0x4B - 0xFF
A1, A2, A3 = 8-bit values totaling 24-bit address
IOs = Status line input/output settings (0 = output, 1 = input; line D0 corresponds to bit b0)
ID = User ID value (decimal notation, 1 to 60)
CP = Control permissions for the learned transcoder (0 = not authorized, 1 = authorized; line D0 corresponds to bit b0)
Data = Value of custom data byte transferred when the option is enabled
Mask = Value used to define which outputs are latched when Latch Mode is enabled (0 = momentary, 1 = latched; line D0 corresponds to bit b0)
Outputs = Current state of the status line outputs (0 = low, 1 = high; line D0 corresponds to bit b0)
Status = States of the status line inputs to be sent (0 = low, 1 = high; line D0 corresponds to bit b0)
Packets = Number of packets to be sent
VAL = Option enable value (0x00 = OFF, 0x01 = ON)
To delete a specific user, perform a Write Specific User operation with A1, A2, A3, and IOs set to 0xFF
Table 5: MT Series Transcoder Serial Interface Engine Command Set
Page 19
Page 18
SER_IO = Input
SER_IO = Output
Read Local Settings
0.08
0.08
0.08
17.00
17.00
17.00
2.80
2.80
2.80
1.06
1.03
1.11
4.00
4.00
4.00
1.73
2.07
1.73
3.10
0.04
3.65
0.04
17.80
0.04
11.14
13.30
10.06
27.44
11.13
28.06
30.22
26.97
44.36
28.05
Min Ready Max Ready Receive Cmd Process Cmd Reply Wait Transmit Reply Finish Process Min Total Time Max Total Time
Write Local Settings
3.11
Definition
Read Next User ID
4.00
40.87
4.00
27.71
1.04
23.95
37.32
1.11
14.30
10.79
2.80
1.73
0.04
2.80
4.00
2.77
17.00
1.04
4.00
17.00
2.80
1.10
0.08
17.00
2.80
26.99
0.08
0.08
17.00
20.40
Read Specific User
Write Specific User
0.08
10.74
Write Next User ID
Read Target Address
1.73
30.23
26.99
4.00
10.07
26.97
1.05
13.31
26.65
2.80
0.04
10.05
26.99
17.00
3.65
9.73
30.24
0.08
2.08
0.04
10.07
27.00
Write Target Address
1.73
**
13.32
30.24
30.23
4.00
2.08
0.04
10.08
10.07
4.00
1.73
3.65
13.32
13.31
1.07
4.00
2.08
0.04
0.04
1.05
4.00
1.73
3.65
3.65
2.80
1.05
4.00
2.08
2.08
2.80
1.06
4.00
1.73
1.73
17.00
2.80
1.07
4.00
4.00
17.00
2.80
1.06
4.00
4.00
0.08
17.00
2.80
1.08
1.07
0.08
17.00
2.80
1.06
30.25
27.00
1.05
Read Latch Mask Value
0.08
17.00
2.80
10.08
2.80
Write Latch Mask value
0.08
17.00
2.80
0.04
2.80
Read Status Outputs
0.08
17.00
2.08
17.00
Write Status Inputs
0.08
17.00
4.00
17.00
Read Confirmation EN
0.08
1.08
0.08
Write Confirmation EN
0.08
2.80
0.08
Read Device Targeting EN
17.00
Write Custom Data Value
Write Device Targeting EN
0.08
Read Custom Data Value
Read Custom Data EN
SER_IO = Output
0.08
Write Custom Data EN
17.00
2.80
1.07
4.00
1.73
3.65
13.33
MinRdy applies when MT is in Encoder Only mode.
MaxRdy applies when MT is in Transcoder mode and time may be longer due to possible receive timeout period.
Receive Command is calculated for 8bytes at 28,800bps (34us/bit).
Transmit Reply is measured on the SER_IO pin from the MT
**Finish Process time for the Write Status Inputs command = 0.06mS + (Packet Time * Number of Packets). See Table 3 for Packet Time.
Table 8: MT Series Transcoder Serial Interface Engine Timings (mS) at 28,800bps
SER_IO = Input
Write Confirmation EN
Read Confirmation EN
Write Status Inputs
Read Status Outputs
Write Latch Mask value
Read Latch Mask Value
Write Custom Data Value
Read Custom Data Value
Write Target Address
Read Target Address
Write Specific User
Read Specific User
Write Next User ID
Read Next User ID
Write Local Settings
Read Local Settings
0.08
0.08
0.08
0.08
0.08
0.08
0.08
0.08
0.08
0.08
0.08
0.08
0.08
0.08
0.08
0.08
0.08
0.08
33.00
33.00
33.00
33.00
33.00
33.00
33.00
33.00
33.00
33.00
33.00
33.00
33.00
33.00
33.00
33.00
33.00
33.00
8.30
8.30
8.30
8.30
8.30
8.30
8.30
8.30
8.30
8.30
8.30
8.30
8.30
8.30
8.30
8.30
8.30
8.30
8.30
1.08
1.06
1.08
1.06
1.07
1.06
1.05
1.05
1.07
1.05
1.07
1.05
1.10
1.04
1.11
1.04
1.06
1.03
1.11
4.00
4.00
4.00
4.00
4.00
4.00
4.00
4.00
4.00
4.00
4.00
4.00
4.00
4.00
4.00
4.00
4.00
4.00
4.00
6.38
5.29
6.38
5.29
6.38
5.29
6.38
5.29
6.38
5.29
6.38
5.29
8.51
5.29
9.58
5.29
6.38
5.29
9.58
0.04
3.65
0.04
3.65
0.04
**
0.04
3.65
0.04
3.65
0.04
10.74
0.04
14.30
0.04
3.65
0.04
17.89
0.04
19.88
22.38
19.88
22.38
19.87
18.79
19.85
22.37
19.87
22.37
19.87
29.46
22.03
33.05
23.11
22.36
19.86
36.59
23.11
52.80
55.30
52.80
55.30
52.79
51.71
52.77
55.29
52.79
55.29
52.79
62.38
54.95
65.93
56.03
55.28
52.78
69.51
56.03
Min Ready Max Ready Receive Cmd Process Cmd Reply Wait Transmit Reply Finish Process Min Total Time Max Total Time
Read Device Targeting EN
33.00
Definition
Write Device Targeting EN
0.08
55.31
Read Custom Data EN
0.08
5.29
8.30
22.39
Write Custom Data EN
33.00
1.07
4.00
3.65
MinRdy applies when MT is in Encoder Only mode.
MaxRdy applies when MT is in Transcoder mode and time may be longer due to possible receive timeout period.
Receive Command is calculated for 8bytes at 9,600bps (104us/bit).
Transmit Reply is measured on the SER_IO pin from the MT
**Finish Process time for the Write Status Inputs command = 0.06mS + (Packet Time * Number of Packets). See Table 3 for Packet Time.
Table 7: MT Series Transcoder Serial Interface Engine Timings (mS) at 9,600bps
Page 21
Page 20
TRANSCODER MODE_IND DEFINITIONS
The MODE_IND line is the primary means of indicating the state of the
transcoder to the user. The table below gives the definitions of the MODE_IND
signals.
Receive Mode
ON during address generation, while CRT/LRN line is HIGH,
then it flashes* when CRT/LRN line is taken LOW. Once the
15-second timer expires or the CRT/LRN line is asserted
again, the MODE_IND line will turn OFF.
Learn Mode
ON while CRT/LRN line is held HIGH until taken LOW to enter
Learn Mode, then it flashes* for 15 seconds until the timer
expires or the CRT/LRN line is asserted again. If the 60th user
profile has been saved, it will blink* 5 times to indicate the next
user profile will overwrite the first.
Serial Interface
Mode
Initialize and pull
all outputs low
ON for as long as the transcoder is receiving data from a
learned user. This only indicates authorized data reception,
not status output activation.
Create Address
Mode
Erase Mode
Power Up
ON while CRT/LRN line is held HIGH for 10 seconds and
Erase Mode is entered, then it turns OFF until the CRT/LRN
line is released. It will then turn back ON again for 2 seconds
to indicate erase completion.
OFF while command is being received (SER_IO = input) and
ON while ACK/reply message is being sent (SER_IO =
output).
*Blink = ON for 1sec and OFF 250mS
*Flash = ON for 65mS and OFF for 65mS
Set the ON timer
time to 10%
Pull the TR_PDN
Line High
No
Is the
ENC_SEL line
high?
Yes
Are any status
lines high?
Yes
Set as encoder
Transmit
Mode
No
Has an
address been
created?
Is the
CRT/LRN line
high?
Yes
No
Is the
ENC_SEL
line high?
Go to
Config.
Mode
No
No
Is the
TR_DATA line
high?
Yes
All status lines
are outputs
All status lines
are inputs
No
Set to Transmit
Mode
Yes
Assemble the
packet
Yes
Send the packet
Go to
Receive
Mode
Set to Receive
Mode
Set status lines
according to
assignments
No
Yes
Is the
SEL_BAUD
line high?
ON timer
timeout?
No
Yes
Yes
Set the baud rate
to 9,600bps
Set the baud rate
to 28,800bps
Did the
Confirm Wait
timer timeout?
No
Pull the TR_PDN
Line Low
Set the OFF timer
to 90%
Mode
Select
No
Any valid
confirmation
data?
Yes
Sleep
Pull the CONFIRM
line high
Table 9: MT Series Transcoder MODE_IND Definitions
LEGAL CONSIDERATIONS
If the transcoder is to be used with a transceiver operating in the 260MHz to
470MHz ISM band in the United States under Part 15.231, then there are some
legal requirements that need to be considered. The FCC requires that the
transmission control something, so the transcoder cannot be used simply for
passing data. The data lines and CONFIRM line must be connected to
something that turns on or off, such as a motor, LED, buzzer, or display.
Application Note AN-00128 goes into this in detail.
The transcoder has the ability to be automatically activated with the Write Status
Inputs command through the SIE. The FCC requires that any automatic
transmission cease within 5 seconds of activation. The MT could exceed this
time depending on the baud rate used, the options that are enabled, and the
number of packets that are sent. Table 3 shows the packet time at each baud
rate with the various options enabled or disabled. The designer needs to be
aware of the time depending on the options that are in use and adjust the packet
counter in the command to ensure that the total time does not exceed 5 seconds.
Application Note AN-00157 goes into the serial commands in more detail and
Application Note AN-00125 goes into the FCC regulations under Part 15.231.
Page 22
Encoder only?
Stop the OFF
Timer
No
Set to Transmit
Mode
Yes
Pull the TR_PDN
line low
Are any status
lines high?
No
Go to
Mode
Select
Sleep
Yes
Are any status
lines high?
Did the
Confirm Bounce
timer timeout?
Yes
Go to
Transmit
Mode
No
No
Yes
Pull the CONFIRM
line low
Is the
CRT/LRN line
high?
No
Yes
Go to
Config.
Mode
Figure 12: MT Series Transcoder Power-up Flowchart
Page 23
Config
Mode
Is the SER_IO
line high?
Receive
Mode
Yes
Yes
Get incoming
serial data
No
Go to
Mode
Select
Did the
RX Mode
timer timeout?
No
No
Is the
ENC_SEL
line high?
Yes
Was a valid
command
received?
Any valid data?
No
Yes
Randomize the
address
No
Yes
Assemble the
confirmation packet
Yes
Start Erase timer
Process command
operation
Is the
CRT/LRN line
high?
Is the
CRT/LRN line
high?
Send reply
message
Send the
confirmation packet
Yes
Did the Erase
timer timeout?
Did the
Timeout timer
timeout?
Set to
Receive Mode
Yes
Did the
Timeout timer
timeout?
Yes
Is the
CRT/LRN line
high?
Is Confirm
enabled?
Reset RX
Mode timer
No
No
Yes
Get and update the
status line
assignments
No
Set to
Transmit Mode
Go to
Mode
Select
Any valid data?
No
Yes
No
Yes
Does the
target address
match the local
address?
Go to
Mode
Select
Write the new
address to memory
Yes
Erase memory
Was the
received packet
targeted?
No
Yes
No
No
Yes
No
Is Confirm
enabled?
No
No
Yes
Is the
CRT/LRN line
high?
AND the Command
Byte with Output
Mask creating
Output Byte
No
Yes
Are any bits
in the Output
Byte high?
Save new status
line assignment
value to memory
Update the Control
Permissions
No
Yes
Is Confirm
enabled?
No
Yes
Send the
confirmation packet
Save new Address
and Control
Permissions
Go to
Mode
Select
Figure 13: MT Series Transcoder Configure Flowchart
Page 24
Set status lines
according to the
assignments
Go to
Mode
Select
No
Is the LATCH
line high?
Yes
XOR Output Byte
with current status
line output states
Output the Output
Byte on the status
lines
Output TXID,
received Data byte,
and CstmData byte
on the SER_IO line
Figure 14: MT Series Transcoder Receive Flowchart
Page 25
TYPICAL APPLICATIONS
DESIGN STEPS TO USING THE MT SERIES
The MT Series transcoder is ideal for replicating button presses for remote
control applications. An example application circuit is shown below.
Default Use
1. Tie ENC_SEL high on one transcoder to put it into Default Encoder Mode.
2. Tie ENC_SEL low on another transcoder to put it into Default Decoder Mode.
3. Get the received address and command on the SER_IO line.
VCC
VCC
10k
2.2k
100k
VCC
100k
VCC
To Processor or PC
To Transceiver
To Transceiver
To Transceiver
1
2
3
4
5
6
7
8
9
10
VCC LICAL-TRC-MT GND
D6
D5
D7
D4
CRT/LRN
D3
ENC_SEL
LATCH
SER_IO
SEL_BAUD
CONFIRM
MODE_IND
TR_PDN
D2
TR_SEL
D1
TR_DATA
D0
20
19
18
17
16
15
14
13
12
11
100k
VCC
VCC
100k
VCC
Creation of an Address and assignment of status lines
VCC
1. Take the CRT/LRN line high while the ENC_SEL line is high to enter Create
Mode.
Figure 15: MT Series Transcoder Application Circuit
SPDT switches are used to select the baud rate and set the latch mode. These
can be tied directly to supply or ground if they will not change.
The TR_PDN line can be connected to the PDN line of a transceiver or it can be
left floating.
SER_IO can be connected to a microprocessor or a PC to program the
transcoder through the serial command set or to record the transmitter identity.
Application Note AN-00157 has sample code.
A LED indicator is attached to the MODE_IND line to provide visual feedback to
the user that an operation is taking place. This line will source a maximum of
25mA, so the limiting resistor may not be needed, depending on the LED chosen
and the brightness desired.
The CONFIRM line is connected to a LED to indicate that the remote device
successfully received the command.
The CRT/LRN and ENC_SEL lines are connected to buttons that will pull the
lines high when pressed. Since the lines do not have internal pull-down resistors,
a 100kΩ resistor is used to pull the line to ground when not in use.
The TR_DATA line is connected directly to the data line of the transceiver.
Data Lines D0 through D7 can be individually set up as either inputs or outputs.
In this example, D4 and D5 have buttons connected to them, so they will be set
up as inputs, and D0 and D6 are set up as outputs. D0 is connected directly to
a piezoelectric buzzer. Line D6 will activate a relay through a transistor buffer
when it goes high. A buffer like this may be needed if the load requires more than
25mA of current or a higher voltage source to activate. The transcoder will turn
on the transistor, which can be selected to provide the appropriate drive levels
to activate the relay.
Page 26
Note that when used in this manner, the device set in Default Decoder Mode will accept all
transmissions, regardless of address. For applications where addressing is not required,
this makes setup extremely easy. For applications that need more users than can be
provided by the MT, an external controller or PC can be used to create a larger user
database. Once a remote address is learned, a valid learned address is required for all
transmissions before the transcoder will respond.
2. The Address will be randomized for as long as the CRT/LRN line is high (the
ENC_SEL is not monitored once Create Mode has been entered). The
MODE_IND line will go high to indicate that the Address is being randomized.
3. Release the CRT/LRN line and the MODE_IND line will begin switching to
indicate that the transcoder is ready to set status line assignments.
4. Take each line that is to be an input high within fifteen seconds.
5. Take the CRT/LRN line high again or let the transcoder time out after fifteen
seconds to exit Create Mode.
Learn another transcoder’s Address
1. Take the CRT/LRN line high then low while the ENC_SEL line is low to enter
Learn Mode.
2. The MODE_IND line will begin switching to indicate that the transcoder is ready
to receive a transmission. On the transmitting side, activate each status line that
is to be authorized. The transcoder will record the Address and the activated
status lines as the Control Permissions.
3. Take the CRT/LRN line high again or let the transcoder time out after fifteen
seconds to exit Learn Mode.
Erase all Addresses in memory
1. Take the CRT/LRN line high while the ENC_SEL line is low and hold for ten
seconds.
2. The MODE_IND line will go high when the CRT/LRN line is activated, then go
low after ten seconds to indicate that the memory has been erased.
Communicate through the serial interface
1. Take the CRT/LRN line high while the SER_IO line is high to enter Serial Mode.
2. Use a microcontroller or serial interface to write the desired serial command to
the transcoder LSB first with 1 start bit, 1 stop bit, and no parity at the baud rate
determined by the SEL_BAUD line.
3. Read the acknowledgement and response (if there is one) from the transcoder
LSB first with 1 start bit, 1 stop bit, and no parity at the baud rate determined by
the SEL_BAUD line.
Page 27
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