CC1110Fx / CC1111Fx
Figure 49: Data Whitening in TX Mode
• Length byte or constant programmable
packet length
14.8.2 Packet Format
The format of the data packet can be
configured and consists of the following items:
• Optional Address byte
• Payload
• Optional 2 byte CRC
• Preamble
• Synchronization word
Optional data whitening
Legend:
Optionally FEC encoded/decoded
Optional CRC-16 calculation
Inserted automatically in TX,
processed and removed in RX.
Optional user-provided fields processed in TX,
processed but not removed in RX.
Preamble bits
(1010...1010)
Data field
8 x n bits
Unprocessed user data (apart from FEC
and/or whitening)
8
8
8 x n bits
16/32 bits
16 bits
bits bits
Figure 50: Packet Format
The preamble pattern is an alternating
sequence of ones and zeros (101010101…).
The minimum length of the preamble is
programmable through the NUM_PREAMBLE
field in the MDMCFG1 register. When enabling
TX, the modulator will start transmitting the
preamble. When the programmed number of
preamble bytes have been transmitted, the
modulator will send the sync word, and then
data from the RFDregister. If no data has been
written to the RFD register when the radio is
done transmitting the programmed number of
preamble bytes, the modulator will continue to
send preamble bytes until the first byte is
written to RFD. It will then send the sync word
followed by the data written to RFD.
packet. A one-byte sync word can be emulated
by setting the SYNC1 value to the preamble
pattern. It is also possible to emulate a 32 bit
sync word by using MDMCFG2.SYNC_MODEset
to 3 or 7. The sync word will then be repeated
twice.
CC1110Fx/CC1111Fx supports both fixed packet
length protocols and variable packet length
protocols. Variable or fixed packet length mode
can be used for packets up to 255 bytes.
Fixed packet length mode is selected by
setting PKTCTRL0.LENGTH_CONFIG=0. The
desired packet length is set by the PKTLEN
register.
In
variable
packet
length
mode,
PKTCTRL0.LENGTH_CONFIG=1, the packet
length is configured by the first byte after the
sync word. The packet length is defined as the
payload data, excluding the length byte and
The synch. word is a two-byte value set in the
SYNC1 and SYNC0 registers. The sync word
provides byte synchronization of the incoming
SWRS033E
Page 193 of 239
TAOS [ TEXAS ADVANCED OPTOELECTRONIC SOLUTIONS ]
