Receive Mode
–
If a destination PAN ID is included in the frame, it must match PAN_ID or must be the broadcast
PAN identifier (0xFFFF).
–
If a short destination address is included in the frame, it must match either SHORT_ADDR or the
broadcast address (0xFFFF).
–
If an extended destination address is included in the frame, it must match EXT_ADDR.
•
Frame type:
–
Beacon frames (0) are only accepted when:
•
FRMFILT1.ACCEPT_FT0_BEACON
= 1
•
Length byte
≥
9
•
The destination address mode is 0 (no destination address).
•
The source address mode is 2 or 3 (i.e., a source address is included).
•
The source PAN ID matches PAN_ID, or PAN_ID equals 0xFFFF.
–
Data (1) frames are only accepted when:
•
FRMFILT1.ACCEPT_FT1_DATA
= 1
•
Length byte
≥
9
•
A destination address and/or source address is included in the frame. If no destination address
is included in the frame, the
FRMFILT0.PAN_COORDINATOR
bit must be set, and the source
PAN ID must equal PAN_ID.
–
Acknowledgment (2) frames are only accepted when:
•
FRMFILT1.ACCEPT_FT2_ACK
= 1
•
Length byte = 5
–
MAC command (3) frames are only accepted when:
•
FRMFILT1.ACCEPT_FT3_MAC_CMD
= 1
•
Length byte
≥
9
•
A destination address and/or source address is included in the frame. If no destination address
is included in the frame, the
FRMFILT0.PAN_COORDINATOR
bit must be set, and the source
PAN ID must equal PAN_ID for the frame to be accepted.
–
Reserved frame types (4, 5, 6, and 7) are only accepted when
•
FRMFILT1.ACCEPT_FT4TO7_RESERVED
= 1 (default is 0)
•
Length byte
≥
9
The following operations are performed before the filtering begins, with no effect on the frame data stored
in the RXFIFO:
•
Bit 7 of the length byte is masked out (don't care).
•
If
FRMFILT1.MODIFY_FT_FILTER
is not equal to zero, the MSB of the frame type subfield of the FCF
is either inverted or forced to 0 or 1.
If a frame is rejected, the radio only starts searching for a new frame after the rejected frame has been
completely received (as defined by the frame-length field) to avoid detecting false SFDs within the frame.
Note that a rejected frame can generate RX overflow if it occurs before the frame is rejected.
Interrupts
When frame filtering is enabled and the filtering algorithm accepts a received frame, an
RX_FRM_ACCEPTED interrupt is generated. It is not generated if frame filtering is disabled or
RX_OVERFLOW or RX_FRM_ABORTED is generated before the filtering result is known.
illustrates the three different scenarios (not including the overflow and abort-error conditions).
236
CC253x Radio
SWRU191C
–
April 2009
–
Revised January 2012
Copyright
©
2009
–
2012, Texas Instruments Incorporated