PHOTO 8. Powering RF with RF.
That's like making chickens with
chicken eggs. What came first, the
receiver or the transmitter??
DIP switch, a piezo speaker, an
ATMega88 filled with CC2500
driver/test/configuration code, and
the SRWF-2500 wireless transceiver.
If you’re feeling bully, the test
board provides ISP programming
portal access for the ATMega88.
Danger, Will Robinson!!
Used in conjunction with
AccessPort, the prospective SRWF-
2500 wireless transceiver user can
establish a communications link
between a pair of SRWF-2500 test boards. Pressing the
TX-SW pushbutton sends a canned message to the
receiving test board which kicks off a squawk of ASCII data
from the receiving node. Thus, the test board can be used
for range testing utilizing various baud rates and RF
2. 4 GHz communications link. Being a SERVO columnist, it’s
my job to expose you to every bit of robotic-possible
electronic gadgetry that I can. This month, you’ve taken a
tour of the RF technology offered by the folks at Sunray
Technology. I’ll make my CC2500 driver firmware available
via the SERVO ftp site. SV
Powering RF Using RF
What you see in Photo 8 is a battery charger that
derives its power from RF. The pA dipole or patch antenna
is attached to J1. Encoded 915 MHz RF energy is emitted
by a local 915 MHz Powercaster transmitter and is fed to
the Powercast P2110 Powerharvester receiver by the
antenna servicing J1. The Powerharvester receiver converts
the received RF energy and stores it into the large holding
capacitor. The power converted and stored by the receiver
is used to charge the THINERGY energy cell.
So what, you say? Well, what does the Photo 8 P2
header legend say? It say’s TI RF2500. That 2500 is a
reference to the CC2500. Thus, this Powercast circuitry and
THINERGY energy cell has the ability to power a CC2500-
based radio platform.
Good Day, Sunray
That’s what the song lyrics would have been if John,
Paul, George, and Ringo had to implement a low power
SRWF-2500 Test Board
CCS C Compiler
Fred Eady can be reached via email at firstname.lastname@example.org.
SERVO 11.2011 39