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14
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.