C2510Fx / CC2511Fx
Whitening
is
enabled
by
setting
If FEC/Interleaving is enabled, everything
following the sync words will be scrambled by
the interleaver and FEC encoded before being
modulated. FEC is enabled by setting
14.8.5
Packet Handling in Receive Mode
When variable packet length mode is enabled,
the first byte is the length byte. The packet
handler stores this value as the packet length
and receives the number of bytes indicated by
the length byte. If fixed packet length mode is
used, the packet handler will accept the
programmed number of bytes.
Next, the packet handler optionally checks the
address and only continues the reception if the
address matches. If automatic CRC check is
enabled, the packet handler computes CRC
and matches it with the appended CRC
checksum.
At the end of the payload, the packet handler
will optionally write two extra packet status
bytes that contain CRC status, link quality
indication and RSSI value.
If a byte is received in the
RFD
register, and it
is not read before the next byte is received,
the radio will enter RX_OVERFLOW state and
the
RFIF.IRQ_RXOVF
flag will be set together
with
RFIF.IRQ_DONE.
An SIDLE strobe
needs to be issued to return to IDLE state.
In receive mode, the demodulator and packet
handler will search for a valid preamble and
the sync word. When found, the demodulator
has obtained both bit and byte synchronism
and will receive the first payload byte.
If FEC/Interleaving is enabled, the FEC
decoder will start to decode the first payload
byte. The interleaver will de-scramble the bits
before any other processing is done to the
data.
If whitening is enabled, the data will be de-
whitened at this stage.
14.9 Modulation Formats
CC2510Fx/CC2511Fx
supports frequency and
phase shift modulation formats. The desired
modulation
format
is
set
in
the
register.
Optionally, the data stream can be Manchester
coded by the modulator and decoded by the
demodulator. This option is enabled by setting
Manchester
encoding is not supported at the same time as
using the FEC/Interleaver option.
14.9.1
Frequency Shift Keying
2-FSK can optionally be shaped by a
Gaussian filter with BT=1, producing a GFSK
modulated signal.
The frequency deviation is programmed with
the
and
values
in the
register. The value has an
exponent/mantissa form, and the resultant
deviation is given by:
f
dev
=
f
ref
2
17
⋅
(8
+
DEVIATION
_
M
)
⋅
2
DEVIATION
_
E
The symbol encoding is shown in Table 66.
Format
2-FSK/GFSK
Symbol
‘0’
‘1’
Coding
- Deviation
+ Deviation
Table 66: Symbol Encoding for 2-FSK/GFSK Modulation
14.9.2
Minimum Shift Keying
The fraction of a symbol period used to
change the phase can be modified with the
setting. This is
equivalent to changing the shaping of the
symbol.
When using MSK
, the complete transmission
(preamble, sync word, and payload) will be
MSK modulated.
Phase shifts are performed with a constant
transition time.
SWRS055D
Page 197 of 243
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