CC2510_15 Datasheet, PDF (200/245 Pages) Texas Instruments – Low-Power SoC (System-on-Chip) with MCU, Memory,2.4 GHz RF Transceiver, and USB Controller

CC2511F8 - Not Recommended for New Designs
13.12.1 Active Modes
The radio has two active modes: receive and
transmit. These modes are activated directly
by writing the SRX and STX command strobes
to the RFST register.
The frequency synthesizer must be calibrated
regularly. CC2510Fx/CC2511Fx has one manual
calibration option (using the SCAL strobe), and
three automatic calibration options, controlled
by the MCSM0.FS_AUTOCAL setting:
• Calibrate when going from IDLE to
either RX or TX (or FSTXON)
• Calibrate when going from either RX or
TX to IDLE automatically
• Calibrate every fourth time when going
from either RX or TX to IDLE
automatically
If the radio goes from TX or RX to IDLE by
issuing an SIDLE strobe, calibration will not be
performed. See Table 71 for timing details
regarding calibration.
When RX is activated, the chip will remain in
receive mode until a packet is successfully
received or the RX termination timer expires
(see Section 13.12.3). Note: The probability
that a false sync word is detected can be
reduced by using PQT, CS, maximum sync
word length, and sync word qualifier mode as
describe in Section 13.10.1. After a packet is
successfully received the radio controller will
then go to the state indicated by the
MCSM1.RXOFF_MODE setting. The possible
destinations are:
• IDLE
• FSTXON: Frequency synthesizer on
and ready at the TX frequency. Activate
TX with STX.
• TX: Start sending preambles
• RX: Start search for a new packet
CC2510Fx / CC2511Fx
Note: When MCSM1.RXOFF_MODE=11 and
a packet has been received, it will take
some time before a valid RSSI value is
present in the RSSI register again even if
the radio has never exited RX mode. This
time is the same as the RSSI response
time discussed in DN505 [12].
Similarly, when TX is active the chip will
remain in the TX state until the current packet
has been successfully transmitted. Then the
state will change as indicated by the
MCSM1.TXOFF_MODE setting. The possible
destinations are the same as for RX.
It is possible to change the state from RX to
TX and vice versa by using the command
strobes. If the radio controller is currently in
transmit and an SRX strobe is written to the
RFST register, the current transmission will be
ended and the transition to RX will be done.
If the radio controller is in RX when the STX or
SFSTXON command strobes are used and
MCSM1.CCA_MODE≠00, the TX-if-CCA function
will be used. If the channel is not clear, the
chip will remain in RX. For more details on
clear channel assessment, see Section
13.10.7 on Page 197.
The SIDLE command strobe can always be
used to force the radio controller to go to the
IDLE state.
13.12.2 Timing
The radio controller controls most timing in
CC2510Fx/CC2511Fx, such as synthesizer
calibration, PLL lock time, and RX/TX
turnaround times. Table 71 shows the timing
for key state transitions when the system clock
frequency is equal to f_Ref and the data rate is
250 kBaud. See DN110 [11] for more details
on how the state transition times changes
under other conditions.
Power on time and XOSC start-up times are
variable, but within the limits stated in Table 11
and Table 12
Note that in a frequency hopping spread
spectrum or a multi-channel protocol it is
possible to reduce the calibration time
significantly. This is explained in Section
13.17.2.
SWRS055G
Page 200 of 236