Texas Instruments CC253x User Manual

SFD LEN
- - - - -
When There Is No Source Address:
FCF+SEQ+Destination
SFD
Interrupt
RX_FRM_ACCEPTED
Interrupt
RX_FRM_DONE
Interrupt
Last
Byte
SRC_MATCH_DONE
Interrupt
SFD LEN
- - - - -
When There Is a Source Address:
FCF+SEQ+Destination+
SourcePANID
SFD
Interrupt
RX_FRM_ACCEPTED
Interrupt
RX_FRM_DONE
Interrupt
M0113-01
Last
Byte
Source
Address
SRC_MATCH_FOUNDinterrupt
may occurduringthisinterval
SRC_MATCH_DONEinterrupt
occursduringthis interval
Receive Mode www.ti.com
When source address matching is enabled and the matching algorithm completes, the
SRC_MATCH_DONE interrupt flag is set, regardless of the result. If a match is found, the
SRC_MATCH_FOUND flag is also set immediately before SRC_MATCH_DONE.
Figure 23-14 illustrates the timing of the setting of flags:
Figure 23-14. Interrupts Generated by Source Address Matching
Tips and Tricks
• The source address table can be modified safely during frame reception. If one address replaces
another while the receiver is active, the corresponding enable bit should be turned off during the
modification. This prevents the RF Core from using a combination of old and new values, because it
only considers entries that are enabled throughout the whole source matching process.
The following measures can be taken to avoid the next received frame overwriting the results from source
address matching:
• Use the appended SRCRESINDEX result instead of the value written to RAM (this is the
recommended approach).
• Read the results from RAM before RX_FRM_ACCEPTED occurs in the next received frame. For the
shortest frame type, this happens after the sequence number, so the total available time (absolute
worst-case with a small safety margin) becomes:
16 μs (required preamble) + 32 μs (SFD) + 128 μs (4 bytes) = 176 μs
• To increase the available time, clear the FSMCTRL.RX2RX_TIME_OFF bit. This adds another 192 μs,
for a total of 368 μs. This also reduces the risk of RX overflow.
240
CC253x Radio SWRU191C–April 2009–Revised January 2012
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Texas Instruments CC253x Specifications

General

Brand	Texas Instruments
Model	CC253x
Category	Microcontrollers
Language	English