Linx Technologies TXM-xxx-KH3 - Manual (Page 9)

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Setting the Transmitter Address
The module has ten address lines. This allows the formation of up to 1,022
(2
10 – 2) unique transmitter-receiver relationships.
Because the address inputs have internal pull-up resistors these pins can
be left floating or tied to GND. These pins may be hardwired or configured
via a microprocessor, DIP switch or jumpers. The receiver’s address
line states must match the transmitter’s exactly for a transmission to be
recognized. If the transmitted address does not match the receiver’s local
address, then the receiver will take no action.
Data Inputs
When the Transmit Enable (TE) line goes high, the states of the eight data
input lines are recorded and encoded for transmission. Because the data
inputs have internal pull-down resistors, these pins can be left floating or
tied to V
CC
. The states of the data lines can be set by switches, jumpers,
microcontrollers or hardwired on the PCB.
The encoder sends the states of the address and data lines three times. If
the TE line is still high, it begins the cycle again. This means that the states
of the data lines are refreshed with each cycle, so the data lines can be
changed without having to pull TE low. There can be up to a 150ms lag
in response as the transmitter finishes one cycle then refreshes and starts
over.
Enabling Transmission
The module’s Transmit Enable (TE) line controls transmission status.
When taken high, the module initiates transmission, which continues until
the line is pulled low or power to the module is removed. In some cases
this line will be wired permanently to V
CC
and transmission controlled by
switching V
CC
to the module. This is particularly useful in applications where
the module powers up and sends a transmission only when a button is
pressed on the remote.
Input Type Selection
The KH3 Series transmitter incorporates the DS Series remote control
encoder, which is designed to be operable with previous generation
products based on Holtek® encoders and decoders. The Holtek®
encoders and decoders have tri-state input lines but the DS has bi-state
lines. Tri-state inputs are connected to ground for zero bits, V
CC
for one
bits, or left unconnected for open bits. Since the DS cannot match this
operation the D_CFG, A_CFG0 and A_CFG1 lines are provided to select
the desired interpretation. The settings must match on both ends.
Pulling the D_CFG line high configures the data inputs as one and zero.
A high on a data line is interpreted as a one bit and a low on the line is
interpreted as a zero bit. Pulling D_CFG low configures the data inputs as
one and open. A high on a data line is interpreted as a one bit and a low on
the line is interpreted as an open bit. The decoder outputs open data bits
as logic low. This is shown in Figure 18.
A_CFG0 and A_CFG1 are used to select the bit type for the address lines.
These are shown in Figure 19.
D_CFG is pulled low internally so that a high on a data line is transmitted
as a one bit and a low on the line is transmitted as an open bit. A_CFG0
is pulled low and A_CFG1 is pulled high internally so that a high on an
address line is interpreted as an open bit and a low as a zero bit.
This configuration matches the Linx OEM products and the most common
implementation of the legacy KH2 Series. This enables customers using
the KH2 Series to populate the KH3 Series without any PCB modifications
since pins 25, 26 and 27 can be left unconnected.
D_CFG Configuration
Configuration Bit Interpretation
D_CFG High Low
0 One Open
1 One Zero
A_CFGO and A_CFG1 Configuration
Configuration Bit Interpretation
A_CFG1 A_CFG0 High Low
0 0 One Zero
0 1 One Open
1 0 Open Zero
1 1 One Zero
Figure 18: D_CFG Configuration
Figure 19: A_CFG0 and A_CFG1 Configuration
Note: All address lines high or all low is not allowed, so at least one line
must be different from the others.