The PW1-928 RF Date
The Patriot PW1-928 is a Lemos
International custom design. It can
perform bi-directional digital data
transfer at distances of over 300 feet.
Transmitting in the 902 to 928 MHz
frequency band, the PW1-928
generates + 7 dBm into a 50Ω load.
The PW1-928’s RX sensitivity is –112
dBm. Its output power is user
The PW1-928 RF module is not a
run-of-the-mill data radio. It uses the
industry standard LoRa direct
sequence chirp spreading protocol.
In that the PW1-928 is a custom design, it makes sense
that its packet transmission data structure is deemed
proprietary. Normally, when something is labeled
“proprietary,” it has unique features that the
manufacturer/designer doesn’t want to fall into the
competition’s hands. In the case of the PW1-928, the
proprietary label is there to protect a simplified data
structure implementation that helps to significantly
improve the data transceiver module’s packet transmission
The PW1-928 is equipped with a microcontroller logic
level Universal Asynchronous Receiver Transmitter (UART)
serial interface. The PW1-928’s UART requires the
appropriate RS-232 converter hardware to attach to true
RS-232 ports that adhere to the RS-232 positive and
negative voltage levels. Data transfer and configuration
setup functions are performed using the PW1-928
module’s UART interface.
The PW1-928 is delivered with its clothes on. The
clothed and shielded version of it is captured in Photo 1.
Under normal circumstances, you
won’t need to access the PW1-928
internal electronics. However, we are
turning all of the knobs and pushing
all of the buttons. So, just in case,
Photo 2 is provided for your viewing
The PW1-928 uses a wideband
“chirp” modulation that complies
with the FCC part 15-247 regulatory
requirements in the 902 to 928 MHz
ISM band. An embedded
running at 16 MHz controls the
show. The PIC interfaces directly to the PW1-928’s
Semtech SX1272 RF transceiver chip. The SX1272
transceivers feature a LoRa long range modem that
provides ultra-long range spread spectrum communication
and high interference immunity. Using Semtech’s patented
LoRa modulation technique, the PW1-928’s SX1272 can
THE DESIGN CYCLE
Get “Patriot”ic with Lemos’ LoRa
■ BY FRED EADY
54 April 2017
Sometimes (as a Design Cycle reader), you only need to know how something works to apply it
to your own application. So, this month, I won’t force a predetermined project on you. Instead,
we are going to dig through the datasheet, push the buttons, and turn the knobs. I have a box
full of PW1-928 RF Data Transceiver Modules, a PW1-928 datasheet, and a PW1-928 evaluation kit.
Let’s figure out how a PW1-928 works.
■ PHOTO 2. Microchip’s PIC microcontrollers are in charge
of thousands of devices. Here’s yet another one.
■ PHOTO 1. The PW1-928 RF Data
Transceiver Module comes in a shielded
package that interfaces using standard
0.1 inch headers.