Linx Technologies LICAL-TRC-MT - Manual (Page 18)

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Design Steps to Using the MT Series
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 Mode.
2. The Address is 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 goes high to indicate that the Address is being
randomized.
3. Release the CRT/LRN line and the MODE_IND line begins 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 to enter Learn Mode.
2. The MODE_IND line begins 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 records 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 Address in memory
1. Take the CRT/LRN line high and hold for ten seconds.
2. The MODE_IND line goes high when the CRT/LRN line is activated,
then 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.
Open Access Mode
The MT Series has the option of accepting all valid transmissions,
regardless of address. This allows the designer to set up an external
database for learned users and control permissions. These 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.
The access can be locked simply by learning a user. From this point on, it
returns to normal operation and requires that the transmission have a valid,
learned address before it responds.
The Restore Default command sent on the serial interface places the
transcoder Open Access Mode. This command removes all existing
settings and restores the transcoder to the factory default condition. This
also enables a default address.
Warning: Care must be taken when using the open access
mode. Any valid MT or MS transmission activates the transcoder and
is output, regardless of whether or not it is from the intended system.
Additional validation steps must be implemented to prevent unintended
activation.
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