User's Guide

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Overview
The HumPRO
TM
Series RF transceiver module offers a number of features
that make it suitable for many data transfer applications. This section
provides a basic overview of the features while following sections dive into
them in more detail.
Addressing
The modules have a very powerful addressing method. Each module is
given a unique 16 or 32 bit address. The receiving modules use an address
mask that determines how it responds to a received transmission.
The addressing and masking allow for the creation of point-to-point,
many-to-one and one-to-many wireless links. This allows the creation of
many network topologies, such as star, tree and mesh. The routing for the
network topology is managed outside the module.
The addressing is the primary configuration when getting started with the
modules. RG-00105, the HumPRO
TM
Addressing Mode Reference Guide
has details about configuring the addressing.
Acknowledgements and Assured Delivery
The modules support assured delivery in the form of acknowledgements
and retries. When the acknowledgements are enabled, the receiving
device sends an acknowledge message to let the sender know that the
transmission was received. If the sender does not get an acknowledgement
it resends the message up to a configurable number of retries. If there is
still no acknowledgement, the module triggers an exception to let the host
processor know of the error.
Command Mode and Data Mode
The module has two main interface modes controlled by the state of the
CMD line. Command mode routes the data coming in on the CMD_DATA_
IN line to the processor for configuring the module. Data mode routes
the data to the transmitter for transmission over-the-air. The CMD line is
normally controlled by an external microcontroller.
Encryption
The module supports AES-128 encryption to provide a secure wireless link.
All of the modules must have encryption enabled and be using the same
key in order for communication to be successful. There are two ways of
entering an encryption key: directly by writing the key to registers through
the Command Data Interface or through a JOIN process.
Streaming Data and Explicit Packets
The module’s default configuration is for streaming data. At some UART
rates the module sends the data at a higher rate over-the-air than it is input
on the UART. This hides the time required for the protocol transactions
and the frequency hopping. The result is that the data appears to stream
through the module with no breaks in the data apparent to the host
processor.
Alternatively, the module can be configured for explicit packet transmission.
This allows the host processor to control when packets are sent and what
data is in each packet
Exceptions and Host Processor Interface
The module has several indicator lines that provide feedback to the host
processor on the module’s operation and current status. This includes an
exception line (EX) that informs the processor when errors occur so that it
can take steps to manage the issue gracefully. The state of the status lines
can also be read through the module’s Command Data Interface to reduce
the number of hardware connections that are required.
Command Data Interface
The module has a Command Data Interface that consists of a set of serial
commands entered through a UART. These are shorter and simpler than AT
commands that are popular with many modules. These commands control
the configuration of the module as well as allow feedback on the operation
and status of the module.
Carrier Sense Multiple Access (CSMA)
The module implements a Carrier Sense Multiple Access method. It listens
to the channel and makes sure that it is clear before it transmits. If the
channel is in use, the module either waits for it to clear or hops to the next
channel depending on its current state. This reduces the overall potential
for interference and improves the robustness of the link.