SmartRF ® CC2420
Receive mode:
Incoming / outgoing
RF data
SFD
FIFOP
Transmit mode:
Preamble
FIFO
(from uC)
b0
b1
b2
b3
b4
b5
b6
b7
b8
b9 b10 b11
s0
s1
FIFOP
FIFO
(from
CC2420)
b0
b1
b2
b3
b4
s2
b8
b9 b10 b11
4 us
Figure 21. Un-buffered test mode, pin activity
Address Recognition
CC2420 includes hardware support for
address recognition, as specified in [1].
Hardware address recognition may be
enabled
/
disabled
using
the
MDMCTRL0.ADR_DECODE
control bit.
Address recognition is based on the
following requirements, listed from section
7.5.6.2 in [1]:
•
The frame type subfield shall not
contain an illegal frame type
•
If the frame type indicates that the
frame is a beacon frame, the
source PAN identifier shall match
macPANId unless macPANId is
equal to 0xFFFF, in which case
the
beacon
frame
shall
be
accepted regardless of the source
PAN identifier.
•
If a destination PAN identifier is
included in the frame, it shall
match macPANId or shall be the
broadcast
PAN
identifier
(0xFFFF).
•
If a short destination address is
included in the frame, it shall
match either macShortAddress or
the broadcast address (0xFFFF).
Otherwise
if
an
extended
destination address is included in
the
frame,
it
shall
match
aExtendedAddress.
•
If only source addressing fields
are included in a data or MAC
command frame, the frame shall
only be accepted if the device is a
PAN coordinator and the source
PAN
identifier
matches
macPANId.
If any of the above requirements are not
satisfied and address recognition is
enabled,
CC2420 will disregard the
incoming frame and flush the data from
the RXFIFO. Only data from the rejected
frame is flushed, data from previously
accepted frames may still be in the
RXFIFO.
The IOCFG0.BCN_ACCEPT control bit
must be set when the PAN identifier
programmed into
CC2420 RAM is equal to
0xFFFF and cleared otherwise. This
particularly applies to active and passive
scans as defined by [1] which requires all
received beacons to be processed by the
MAC sublayer.
Incoming frames with reserved frame
types (FCF frame type subfield is 4, 5, 6 or
7)
is
however
accepted
if
the
RESERVED_FRAME_MODE
control bit in
MDMCTRL0
is set. In this case, no further
address recognition is performed on these
frames. This option is included for future
expansions
of
the
IEEE
802.15.4
standard.
Chipcon AS SmartRF® CC2420 Preliminary Datasheet (rev 1.2), 2004-06-09
Page 39 of 87
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