CC1110 Datasheet, PDF (162/203 Pages) Texas Instruments – True System-on-Chip with Low Power RF Transceiver and 8051 MCU

CC1110
Bit Field name Description
7:0 RSSI
RSSI value
Table 45: Received packet status byte 1
(first byte appended after the data)
Bit Field name Description
7
CRC_OK
1: CRC for received data OK (or
CRC disabled)
0: CRC error in received data
6:0 LQI
The Link Quality Indicator
estimates how easily a received
signal can be demodulated
Table 46: Received packet status byte 2
(second byte appended after the data)
Note that register fields that control the
packet handling features should only be
altered when CC1110 is in the IDLE state.
15.8.1 Data whitening
From a radio perspective, the ideal over
the air data are random and DC free. This
results in the smoothest power distribution
over the occupied bandwidth. This also
gives the control loops in the receiver
uniform operation conditions (no data
dependencies).
Real world data often contain long
sequences of zeros and ones.
Performance can then be improved by
whitening the data before transmitting, and
de-whitening in the receiver. With CC1110,
this can be done automatically by setting
PKTCTRL0.WHITE_DATA=1. All data,
except the preamble and the sync word,
are then XOR-ed with a 9-bit pseudo-
random (PN9) sequence before being
transmitted. At the receiver end, the data
are XOR-ed with the same pseudo-
random sequence. This way, the whitening
is reversed, and the original data appear in
the receiver.
Setting PKTCTRL0.WHITE_DATA=1 is
recommended for all uses, except when
over-the-air compatibility with other
systems is needed.
15.8.2 Packet format
The format of the data packet can be
configured and consists of the following
items:
• Preamble
• Synchronization word
• Length byte or constant
programmable packet length
• Optional Address byte
• Payload
• Optional 2 byte CRC
The preamble pattern is an alternating
sequence of ones and zeros
(01010101…). The minimum length of the
preamble is programmable. When
enabling TX, the modulator will start
transmitting the preamble. When the
programmed number of preamble bytes
has been transmitted, the modulator will
send the sync word and then data from the
RFD register.
The number of preamble bytes is
programmed
with
the
MDMCFG1.NUM_PREAMBLE value.
The synchronization word is a two-byte
value set in the SYNC1 and SYNC0
registers. The sync word provides byte
synchronization of the incoming 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
CC1110 PRELIMINARY Datasheet (Rev. 1.01) SWRS033A Page 162 of 202