CC2510FX Datasheet, PDF (198/253 Pages) List of Unclassifed Manufacturers – True System-on-Chip with Low Power RF Transceiver and 8051 MCU

CC2510Fx / CC2511Fx
To avoid compensating for frequency
offsets measured without a valid signal in
the RF channel, FREQEST.FREQOFF_EST
is copied to an internal register when
issuing the SAFC strobe in RX, and when
a sync word is detected. If SAFC was
issued in RX, this internal value is added
to FSCTRL0.FREQOFF after exiting RX.
Issuing SAFC when not in RX will
immediately add the internal register value
to FSCTRL0.FREQOFF. Thus, the SAFC
strobe should be issued when currently
receiving a packet, or outside the RX
state.
Note that frequency offset compensation is
not supported for OOK modulation.
15.7.2 Bit Synchronization
The bit synchronization algorithm extracts
the clock from the incoming symbols. The
algorithm requires that the expected data
rate is programmed as described in
Section 15.5 on page 196. Re-
synchronization is performed continuously
to adjust for error in the incoming symbol
rate.
15.7.3 Byte synchronization
Byte synchronization is achieved by a
continuous sync word search. The sync
word is a 16 or 32 bit configurable field
that is automatically inserted at the start of
the packet by the modulator in transmit
mode. The demodulator uses this field to
find the byte boundaries in the stream of
bits. The sync word will also function as a
system identifier, since only packets with
the correct predefined sync word will be
received. The sync word detector
correlates against the user-configured 16-
bit sync word. The correlation threshold
can be set to 15/16 bits match or 16/16
bits match. The sync word can be further
qualified using the preamble quality
indicator mechanism described below
and/or a carrier sense condition. The sync
word is programmed with SYNC1 and
SYNC0.
In order to make false detections of sync
words less likely, a mechanism called
preamble quality indication (PQI) can be
used to qualify the sync word. A threshold
value for the preamble quality must be
exceeded in order for a detected sync
word to be accepted. See section 15.10.2
on page 203 for more details.
15.8 Packet Handling Hardware Support
The CC2510Fx/CC2511Fx has built-in
hardware support for packet oriented radio
protocols.
In transmit mode, the packet handler will
add the following elements to the packet
stored to be transmitted:
• A programmable number of preamble
bytes. Four preamble bytes are
recommended.
• A two byte Synchronization Word. Can
be duplicated to give a 4-byte sync
word. (Recommended).
• Optionally whiten the data with a PN9
sequence.
• Optionally Interleave and Forward
Error Code the data.
• Optionally compute and add a CRC
checksum over the data field.
In receive mode, the packet handling
support will de-construct the data packet:
• Preamble detection.
• Sync word detection.
• Optional one byte address check.
• Optionally compute and check CRC.
• Optionally append two status bytes
(see Table 59 and Table 60) with
RSSI value, Link Quality Indication
and CRC status.
Bit Field name Description
7:0 RSSI
RSSI value
Table 59: Received packet status byte 1
(first byte appended after the data)
CC2510Fx/CC2511Fx PRELIMINARY Data Sheet (Rev. 1.2) SWRS055A Page 198 of
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