CC1150-RTR1 datasheet(27/67 Pages) TI

27 / 67 page

CC1150

SWRS037A

Page 27 of 60

IOCFGx.GDOx_CFG=0x03

configurations are

associated with the TX FIFO. See Table 24 for

more information.

b) SPI Polling

The PKTSTATUS register can be polled at a

given rate to get information about the current

GDO2 and GDO0 values respectively. The

TXBYTES

to get information about the number of bytes in

the TX FIFO. Alternatively, the number of

bytes in the TX FIFO can be read from the

chip status byte returned on the MISO line

each time a header byte, data byte, or

command strobe is sent on the SPI bus.

It is recommended to employ an interrupt

driven solution due to that when using SPI

polling, there is a small, but finite, probability

that a single read from registers PKTSTATUS

and TXBYTES is being corrupt. The same is

the case when reading the chip status byte.

This is explained in the

CC1150 Errata Notes [8]

Refer to the TI website for SW examples [12]

14 Modulation Formats

CC1150 supports amplitude, frequency and

phase shift modulation formats. The desired

modulation

format

set

the

MDMCFG2.MOD_FORMAT

Optionally, the data stream can be Manchester

coded by the modulator. This option is enabled

setting

MDMCFG2.MANCHESTER_EN=1.

Manchester encoding cuts the effective data

rate in half, and thus Manchester is not

supported for 500 kBaud. Further note that

Manchester encoding is not supported at the

same time as using the FEC/Interleaver option

or when using MSK modulation.

14.1

Frequency Shift Keying

CC1150 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.

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:

DEVIATION

xosc

dev

DEVIATION

)

(

⋅

The symbol encoding is shown in Table 19.

Format

Symbol

Coding

2-FSK/GFSK

‘0’

– Deviation

‘1’

+ Deviation

Table 19: Symbol Encoding for 2-FSK/GFSK

Modulation

14.2

Minimum Shift Keying

When using MSK

1, 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

Identical to offset QPSK with half-sine

shaping (data coding may differ)

used to change the phase can be modified

with the DEVIATN.DEVIATION_M setting.

This is equivalent to changing the shaping of

the symbol.

Note that when using MSK, Manchester

encoding

must

disabled

setting

MDMCFG2.MANCHESTER_EN=0

. Further note

that the MSK modulation format implemented

CC1150 inverts the data compared to e.g.

signal generators.

CC1150-RTR1 Datasheet(PDF) 27 Page - Texas Instruments

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