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The Command Data Interface
The TT Series transceiver has a serial Command Data Interface (CDI)
that offers the option to configure and control the transceiver through
software instead of through hardware. This interface consists of a standard
UART with a serial command set. This allows for fewer connections in
applications controlled by a microcontroller as well as for more control and
advanced features than can be offered through hardware pins alone.
The serial port uses the CMD_DATA_IN and CMD_DATA_OUT lines as a
UART. An automatic baud rate detection system allows the interface to run
at a variable data rate from 9.6kbps to 57.6kbps.
The Command Data Interface has two sets of operators. One is a set
of commands that performs specific tasks and the other is a set of
parameters that are for module configuration and status reporting. These
are shown in Figure 28.
TT Series Transceiver Command Data Interface Reference Guide has full
details on each command. Some key features available with the serial
interface are:
•
Configure the module through software instead of setting the hardware
lines.
•
Change the output power, providing the ability to lower power
consumption when signal levels are good and extend battery life.
•
Individually set which status lines are inputs and outputs.
•
Individually set status line outputs to operate as momentary or latched.
•
Add or remove specific paired devices.
•
Individually set Permission Masks that prevent certain paired devices
from activating certain status line outputs.
•
Change the module’s local address for production or tracking purposes
or to replace a lost or broken product.
•
Put the module into a low power state to conserve battery power.
•
Receive the entire control message serially instead of needing to
monitor individual status lines. Get the IU address for logging access
attempts.
•
Receive control messages from unpaired modules, allowing for
expansion of the system beyond the maximum of 40 paired units.
Access control and address validation can be undertaken by an
external processor or PC with more memory than the module.
•
Serially configure and control acknowledge messages.
•
Send and receive 2 bytes (16 bits) of custom data with each command
message and acknowledge message.
•
Serially initiate transmission of control messages instead of triggering
the status line inputs.
•
Set interrupts to notify an external processor when specific events
occur, such as receiving a control message.
•
Read out the RSSI value for the last received packet and the current
ambient RF level.
•
Set the receiver duty cycle for automatically powering on and off to
save battery power.
The serial interface offers a great deal of flexibility for use more complicated
designs. Please see Reference Guide RG-00103: the TT Series Command
Data Interface for details on the CDI. A list of the serial commands is shown
in Figure 28 for reference.
