LICAL-TRC-MT001 Linx Technologies, Inc., LICAL-TRC-MT001 Datasheet - Page 14

• Manufacturer Part Number: LICAL-TRC-MT001
• Description: Mt Series Transcoder Data Guide
• Manufacturer: Linx Technologies, Inc.

TYPICAL APPLICATIONS
Figure 15: MT Series Transcoder Application Circuit
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VCC
The MT Series transcoder is ideal for replicating button presses for remote
control applications. An example application circuit is shown below.
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.
100k
100k
VCC
VCC
To Processor or PC
To Transceiver
10k
To Transceiver
To Transceiver
2.2k
VCC
10
1
2
3
4
5
6
7
8
9
VCC
D6
D7
CRT/LRN
ENC_SEL
SER_IO
CONFIRM
TR_PDN
TR_SEL
TR_DATA
LICAL-TRC-MT
SEL_BAUD
MODE_IND
LATCH
GND
D5
D4
D3
D2
D1
D0
20
19
18
17
16
15
14
13
12
11
100k
100k
VCC
VCC
VCC
VCC
DESIGN STEPS TO USING THE MT SERIES
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.
Creation of an Address and assignment of status lines
1. Take the CRT/LRN line high while the ENC_SEL line is high to enter Create
2. The Address will be randomized for as long as the CRT/LRN line is high (the
3. Release the CRT/LRN line and the MODE_IND line will begin switching to
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
Learn another transcoder’s Address
1. Take the CRT/LRN line high then low while the ENC_SEL line is low to enter
2. The MODE_IND line will begin switching to indicate that the transcoder is ready
3. Take the CRT/LRN line high again or let the transcoder time out after fifteen
Erase all Addresses in memory
1. Take the CRT/LRN line high while the ENC_SEL line is low and hold for ten
2. The MODE_IND line will go high when the CRT/LRN line is activated, then go
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
3. Read the acknowledgement and response (if there is one) from the transcoder
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.
Mode.
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.
indicate that the transcoder is ready to set status line assignments.
seconds to exit Create Mode.
Learn Mode.
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.
seconds to exit Learn Mode.
seconds.
low after ten seconds to indicate that the memory has been erased.
the transcoder LSB first with 1 start bit, 1 stop bit, and no parity at the baud rate
determined by the SEL_BAUD line.
LSB first with 1 start bit, 1 stop bit, and no parity at the baud rate determined by
the SEL_BAUD line.
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