Filtering Scenarios (Exceptions Generated During Reception) - Texas Instruments CC253x User Manual

Receive Mode
SFD LEN
Filtering is Enabled, Frame Rejected
SFD
Interrupt
Filtering is Enabled, Frame Accepted
SFD
Interrupt
Filtering is Disabled
SFD
Interrupt
Figure 23-12. Filtering Scenarios (Exceptions Generated During Reception)
The FSMSTAT1.SFD register bit goes high when a start-of-frame delimiter is completely received and
remains high until either the last byte in MPDU is received or the received frame has failed to pass
address recognition and been rejected.
Tips and Tricks
The following register settings must be configured correctly:
• FRMFILT0.PAN_COORDINATOR must be set if the device is a PAN coordinator, and cleared if not.
• FRMFILT0.MAX_FRAME_VERSION must correspond to the supported version(s) of the IEEE 802.15.4
standard.
• The local address information must be loaded into RAM.
To avoid completely the receiving of frames during energy-detection scanning, set FRMCTRL0.RX_MODE =
11b and then (re)start RX. This disables symbol search and thereby prevents SFD detection.
To resume normal RX mode, set FRMCTRL0.RX_MODE = 00b and (re)start RX.
During operation in a busy IEEE 802.15.4 environment, the radio receives large numbers of nonintended
acknowledgment frames. To block reception of these frames effectively, use the
FRMFILT1.ACCEPT_FT2_ACK bit to control when acknowledgment frames should be received:
• Set FRMFILT1.ACCEPT_FT2_ACK after successfully starting a transmission with acknowledgment
request, and clear the bit again after the acknowledgment frame has been received or the time-out has
been reached.
226
CC253x Radio
FCF + SEQ + Destination +
Source PAN ID
Frame
Rejected
RX_FRM_ACCEPTED
Interrupt
FIFOP interrupt occurs during this interval
(Depending on
Copyright © 2009–2014, Texas Instruments Incorporated
Remainder of Received Frame
FIFOP interrupt occurs during this interval
(Depending on
FIFOPCTRL
Value)
FIFOPCTRL
SWRU191F – April 2009 – Revised April 2014
www.ti.com
SFD Search
Resumed
Value)
RX_FRM_DONE
Interrupt
RX_FRM_DONE
Interrupt
M0112-01
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