CC1100E Datasheet, PDF (38/98 Pages) Texas Instruments – Low-Power Sub-GHz RF Transceiver(470-510 MHz & 950-960 MHz)

It is recommended to employ an interrupt
driven solution since high rate SPI polling
reduces the RX sensitivity. Furthermore, as
explained in Section 10.3 and the CC1100E
Errata Note [5], when using SPI polling, there
is a small, but finite, probability that a single
16 Modulation Formats
The CC1100E supports amplitude, frequency,
and phase shift modulation formats. The
desired modulation format is set in the
MDMCFG2.MOD_FORMAT register.
Optionally, the data stream can be Manchester
coded by the modulator and decoded by the
demodulator. This option is enabled by setting
16.1 Frequency Shift Keying
The CC1100E has the possibility to use
Gaussian shaped 2-FSK (GFSK). The 2-FSK
signal is then shaped by a Gaussian filter with
BT = 1, producing a GFSK modulated signal.
This spectrum-shaping feature improves
adjacent channel power (ACP) and occupied
bandwidth.
In ‘true’ 2-FSK systems with abrupt frequency
shifting, the spectrum is inherently broad. By
making the frequency shift ‘softer’, the
spectrum can be made significantly narrower.
Thus, higher data rates can be transmitted in
the same bandwidth using GFSK.
When 2-FSK/GFSK modulation is used, the
DEVIATN register specifies the expected
frequency deviation of incoming signals in RX
and should be the same as the TX deviation
for demodulation to be performed reliably and
robustly.
16.2 Minimum Shift Keying
When using MSK¹, the complete transmission
(preamble, sync word, and payload) will be
MSK modulated.
Phase shifts are performed with a constant
transition time. The fraction of a symbol period
used to change the phase can be modified
with the DEVIATN.DEVIATION_M setting.
1 _{Identical to offset QPSK with half-sine}
shaping (data coding may differ).
CC1100E
read from registers PKTSTATUS , RXBYTES
and TXBYTES is being corrupt. The same is
the case when reading the chip status byte.
Refer to the TI website for SW examples ([9]
and [10]).
MDMCFG2.MANCHESTER_EN=1.
Note: Manchester encoding is not
supported at the same time as using the
FEC/Interleaver option or when using MSK
modulation.
The frequency deviation is programmed with
the DEVIATION_M and DEVIATION_E values
in the DEVIATN register. The value has an
exponent/mantissa form, and the resultant
deviation is given by:
f _dev

f _xosc
2¹⁷
 (8  DEVIATION _ M )  2^{DEVIATION _ E}
The symbol encoding is shown in Table 27.
Format
2-FSK/GFSK
Symbol
‘0’
‘1’
Coding
– Deviation
+ Deviation
Table 27: Symbol Encoding for 2-FSK/GFSK
Modulation
This is equivalent to changing the shaping of
the symbol. The DEVIATN register setting has
no effect in RX when using MSK.
When
using
MSK,
Manchester
encoding/decoding should be disabled by
setting MDMCFG2 MANCHESTER_EN = 0
The MSK modulation format implemented in
the CC1100E inverts the sync word and data
compared to e.g. signal generators.
SWRS082
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