CC2430 Datasheet, PDF (173/212 Pages) Texas Instruments – A True System-on-Chip solution for 2.4 GHz IEEE 802.15.4 / ZigBee-TM

CC2430
Radio : System Considerations and Guidelines
14.31 System Considerations and Guidelines
14.31.1 SRD regulations
International regulations and national laws
regulate the use of radio receivers and
transmitters. SRDs (Short Range Devices) for
license free operation are allowed to operate
in the 2.4 GHz band worldwide. The most
important regulations are ETSI EN 300 328
and EN 300 440 (Europe), FCC CFR-47 part
15.247 and 15.249 (USA), and ARIB STD-T66
(Japan).
14.31.2 Frequency hopping and multi-channel systems
The 2.4 GHz band is shared by many systems
both in industrial, office and home
environments. CC2430 uses direct sequence
spread spectrum (DSSS) as defined by [1] to
spread the output power, thereby making the
communication link more robust even in a
noisy environment.
With CC2430 it is also possible to combine
both DSSS and FHSS (frequency hopping
spread spectrum) in a proprietary non-IEEE
802.15.4 system. This is achieved by
reprogramming the operating frequency (see
the Frequency and Channel Programming
section on page 169) before enabling RX or
TX. A frequency synchronization scheme must
then be implemented within the proprietary
MAC layer to make the transmitter and
receiver operate on the same RF channel.
14.31.3 Data burst transmissions
The data buffering in CC2430 lets the user
have a lower data rate link between the CPU
and the radio module than the RF bit rate of
250 kbps. This allows the CPU to buffer data
at its own speed, reducing the workload and
timing requirements. DMA transfers may be
used to efficiently move data to and from the
radio FIFOs.
The relatively high data rate of CC2430 also
reduces the average power consumption
compared to the 868 / 915 MHz bands defined
by [1], where only 20 / 40 kbps are available.
CC2430 may be powered up a smaller portion
of the time, so that the average power
consumption is reduced for a given amount of
data to be transferred.
14.31.4 Crystal accuracy and drift
A crystal accuracy of ±40 ppm is required for
compliance with IEEE 802.15.4 [1]. This
accuracy must also take ageing and
temperature drift into consideration.
A crystal with low temperature drift and low
aging could be used without further
compensation. A trimmer capacitor in the
crystal oscillator circuit (in parallel with C191 in
Figure 6) could be used to set the initial
frequency accurately.
For non-IEEE 802.15.4 systems, the robust
demodulator in CC2430 allows up to 140 ppm
14.31.5 Communication robustness
CC2430 provides very good adjacent, alternate
and co channel rejection, image frequency
suppression and blocking properties. The
CC2430 performance is significantly better than
the requirements imposed by [1]. These are
14.31.6 Communication security
The hardware encryption and authentication
operations in CC2430 enable secure
total frequency offset between the transmitter
and receiver. This could e.g. relax the
accuracy requirement to 60 ppm for each of
the devices.
Optionally in a star network topology, the full-
function device (FFD) could be equipped with
a more accurate crystal thereby relaxing the
requirement on the reduced-function device
(RFD). This can make sense in systems where
the reduced-function devices ship in higher
volumes than the full-function devices.
highly important parameters for reliable
operation in the 2.4 GHz band, since an
increasing number of devices/systems are
using this license free frequency band.
communication, which is required for many
applications. Security operations require a lot
CC2430 Data Sheet (rev. 2.1) SWRS036F
Page 173 of 211