CC2510FX Datasheet, PDF (211/253 Pages) List of Unclassifed Manufacturers – True System-on-Chip with Low Power RF Transceiver and 8051 MCU

CC2510Fx / CC2511Fx
15.10.4 on page 205 for details on Carrier
Sense.
For OOK modulation, lack of carrier sense is
only considered valid after eight symbol
periods. Thus, the MCSM2.RX_TIME_RSSI
function can be used in OOK mode when the
distance between “1” symbols is 8 or less.
If RX terminates due to no carrier sense when
the MCSM2.RX_TIME_RSSI function is used,
or if no sync word was found when using the
MCSM2.RX_TIME timeout function, the chip
will always go back to IDLE. Otherwise, the
MCSM1.RXOFF_MODE setting determines the
state to go to when RX ends.
15.13 Frequency Programming
The
frequency
programming
in
CC2510Fx/CC2511Fx
is designed to minimize the programming
needed in a channel-oriented system.
To set up a system with channel numbers, the
desired channel spacing is programmed with
the
MDMCFG0.CHANSPC_M
and
MDMCFG1.CHANSPC_E registers. The channel
spacing registers are mantissa and exponent
respectively.
The base or start frequency is set by the 24 bit
frequency word located in the FREQ2, FREQ1
and FREQ0 registers. This word will typically
be set to the centre of the lowest channel
frequency that is to be used.
The desired channel number is programmed
with the 8-bit channel number register,
CHANNR.CHAN, which is multiplied by the
channel offset. The resultant carrier frequency
is given by:
( ( )) f _carrier
=
f _XOSC
2¹⁶
⋅
FREQ + CHAN
⋅
(256 + CHANSPC
_ M ) ⋅ 2 ^{CHANSPC _ E −2}
With a 26 MHz crystal the maximum channel
spacing is 405 kHz. To get e.g. 1 MHz channel
spacing one solution is to use 333 kHz
channel spacing and select each third channel
in CHANNR.CHAN.
The preferred IF frequency is programmed
with the FSCTRL1.FREQ_IF register. The IF
frequency is given by:
f _IF
=
f _XOSC
2¹⁰
⋅ FREQ _ IF
Note that the SmartRF^® Studio software
automatically calculates the optimum
FSCTRL1.FREQ_IF register setting based on
channel spacing and channel filter bandwidth.
If any frequency programming register is
altered when the frequency synthesizer is
running, the synthesizer may give an
undesired response. Hence, the frequency
programming should only be updated when
the radio is in the IDLE state.
15.14 VCO
The VCO is completely integrated on-chip.
15.14.1 VCO and PLL Self-Calibration
The VCO characteristics will vary with
temperature and supply voltage changes, as
well as the desired operating frequency. In
order to ensure reliable operation,
CC2510Fx/CC2511Fx includes frequency
synthesizer self-calibration circuitry. This
calibration should be done regularly, and must
be performed after turning on power and
before using a new frequency (or channel).
The number of XOSC cycles for completing
the PLL calibration is given in Table 66 on
page 210.
The calibration can be initiated automatically
or manually. The synthesizer can be
automatically calibrated each time the
synthesizer is turned on, or each time the
synthesizer is turned off. This is configured
with the MCSM0.FS_AUTOCAL register setting.
In manual mode, the calibration is initiated
when the SCAL command strobe is activated
in the IDLE mode.
Note that the calibration values are maintained
in power-down modes PM2/3, so the
calibration is still valid after waking up from
these power-down modes (unless supply
voltage or temperature has changed
significantly).
CC2510Fx/CC2511Fx PRELIMINARY Data Sheet (Rev. 1.2) SWRS055A Page 211 of 252