CC2430 Datasheet, PDF (189/234 Pages) Texas Instruments – A True System-on-Chip solution for 2.4 GHz IEEE 802.15.4 / ZigBee-TM

CC2430
The external components should be as
small as possible (0402 is recommended)
and surface mount devices must be used.
If using any external high-speed digital
devices, caution should be used when
placing these in order to avoid interference
with the RF circuitry.
14.33 Antenna Considerations
CC2430 can be used together with various
types of antennas. A differential antenna
like a dipole would be the easiest to
interface not needing a balun (balanced to
un-balanced transformation network).
The length of the λ/2-dipole antenna is
given by:
L = 14250 / f
where f is in MHz, giving the length in cm.
An antenna for 2450 MHz should be 5.8
cm. Each arm is therefore 2.9 cm.
Other commonly used antennas for short-
range communication are monopole,
helical and loop antennas. The single-
ended monopole and helical would require
a balun network between the differential
output and the antenna.
Monopole antennas are resonant
antennas with a length corresponding to
one quarter of the electrical wavelength
(λ/4). They are very easy to design and
can be implemented simply as a “piece of
wire” or even integrated into the PCB.
The length of the λ/4-monopole antenna is
given by:
L = 7125 / f
where f is in MHz, giving the length in cm.
An antenna for 2450 MHz should be 2.9
cm.
14.34 CSMA/CA Strobe Processor
The Command Strobe/CSMA-CA
Processor (CSP) provides the control
interface between the CPU and the Radio
module in the CC2430.
The CSP interfaces with the CPU through
the SFR register RFST and the RF
registers CSPX, CSPY, CSPZ, CSPT and
CSPCTRL. The CSP produces interrupt
requests to the CPU. In addition the CSP
A Development Kit, CC2430DK, with a
fully assembled Evaluation Module is
available. It is strongly advised that this
reference layout is followed very closely in
order to obtain the best performance.
The schematic, BOM and layout Gerber
files for the reference designs are all
available from the Chipcon website.
Non-resonant monopole antennas shorter
than λ/4 can also be used, but at the
expense of range. In size and cost critical
applications such an antenna may very
well be integrated into the PCB.
Enclosing the antenna in high dielectric
constant material reduces the overall size
of the antenna. Many vendors offer such
antennas intended for PCB mounting.
Helical antennas can be thought of as a
combination of a monopole and a loop
antenna. They are a good compromise in
size critical applications. Helical antennas
tend to be more difficult to optimize than
the simple monopole.
Loop antennas are easy to integrate into
the PCB, but are less effective due to
difficult impedance matching because of
their very low radiation resistance.
For low power applications the differential
antenna is recommended giving the best
range and because of its simplicity.
The antenna should be connected as
close as possible to the IC. If the antenna
is located away from the RF pins the
antenna should be matched to the feeding
transmission line (50 Ω).
interfaces with the MAC Timer by
observing MAC Timer overflow events.
The CSP allows the CPU to issue
command strobes to the radio thus
controlling the operation of the radio.
The CSP has two modes of operation as
follows, which are described below.
• Immediate Command Strobe
execution.
• Program execution
CC2430 PRELIMINARY Data Sheet (rev. 1.03) SWRS036A
Page 189 of 232