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Theory of Operation
The HumPRCTM Series transceiver is a low-cost, high-performance
synthesized FSK transceiver. Figure 19 shows the module’s block diagram.
The HumPRCTM Series transceiver operates in the 863 to 870MHz
frequency band. The transmitter output power is programmable, though
the maximum power is automatically limited on the higher channels to
comply with ETSI regulations. The range varies depending on the antenna
implementation and the local RF environment. When operating near the
maximum range, there can be higher packet loss when transmitting on the
higher channels due to output power limiting, although it is anticipated that
most customers won’t notice any difference since the transceiver utilizes 70
channels for transmissions.
The RF carrier is generated directly by a frequency synthesizer that includes
an on-chip VCO. The received RF signal is amplified by a low noise
amplifier (LNA) and down-converted to I/Q quadrature signals. The I/Q
signals are digitized by ADCs.
A low-power onboard communications processor performs the radio
control and management functions including Automatic Gain Control
(AGC), filtering, demodulation and packet synchronization. A control
processor performs the higher level functions and controls the serial and
hardware interfaces.
A crystal oscillator generates the reference frequency for the synthesizer
and clocks for the ADCs and the processor.
Figure 19: HumPRCTM Series Transceiver RF Section Block Diagram
PA
LNA
0
90
FREQ
SYNTH
ADC
ADC
DEMODULATOR
MODULATOR
ANTENNA PROCESSORGPIO /
INTERFACE
Module Description
The HumPRCTM Series remote control transceiver module is a completely
integrated RF transceiver and processor that is designed to send the
logic state of its inputs to a remote unit and replicate the logic states of
the remote unit’s inputs. This allows for the easy creation of basic remote
control systems.
The module operates through a series of dedicated I/O lines, resulting in
a hardware design that does not need any software development. The
module does have a serial interface that allows for some configuration in
applications that need specific control. This interface is likely not needed for
basic remote control applications.
Since this module can act as both transmitter and receiver, terminology and
descriptions are important. This guide uses the term Initiating Unit (IU) to
describe a module that is transmitting commands. Responding Unit (RU) is
used to describe a module that is receiving commands.
The module has 8 status lines numbered S0 through S7. These can be set
as inputs for buttons or contacts or as outputs to drive application circuitry.
When S0 is taken high on the IU, S0 goes high on the RU, and so forth. A
line that is an input on one side needs to be set as an output on the other
side.
The HumPRCTM Series adds a remote control application layer to the
protocol stack used by the HumPROTM Series data modem. This enables
the simple creation of remote control systems that benefit from the robust
feature set of the protocol stack, such as a fast locking Listen Before Talk
and Adaptive Frequency Agility (LBT+AFA) algorithm, AES128 encryption,
32-bit addressing, assured delivery and a simple Join Process for
associating multiple modules with each other.
As a result, much of the HumPRCTM Series terminology is the same as the
HumPROTM Series. Likewise, most of the software registers are the same,
though some do not apply to the remote control application.
A result of this common protocol stack is that HumPRCTM Series
transmissions can be received by another HumPRCTM Series module for
simple remote control applications or by a HumPROTM Series module for
applications that want to combine data transmissions (such as sensor
values) with remote control functionality.
