CC2400 Chipcon AS, CC2400 Datasheet - Page 31

• Manufacturer Part Number: CC2400
• Description: 2.4 GHz RF Transceiver
• Manufacturer: Chipcon AS

Radio control state machine
CC2400
used to switch between different operation
states (modes). The change of state is
done either by writing to command strobe
registers, or using dedicated pins.
Before using the radio in either RX or TX
mode, the main crystal oscillator must be
turned on and become stable. The crystal
oscillator has a start-up time given in
Electrical Specifications, during which its
output is gated internally to avoid timing
problems stemming from too narrow clock
pulses. The crystal oscillator is controlled
by accessing the SXOSCON/SXOSCOFF
command
XOSC16M_STABLE
register returned during address transfer
indicates whether the oscillator is running
and stable or not (See Table 4). This
status register can be polled when waiting
for the oscillator to start.
The frequency synthesizer (FS) can be
started by either accessing the command
strobe register SFSON or by using the RX
and TX control pins. The FS will then enter
its
Chipcon AS
self-calibration
has a built-in state machine that is
Radio Off
Figure 14. Radio control state diagram using the RX and TX pins
SmartRF
strobe
®
bit
CC2400 PRELIMINARY Datasheet (rev. 1.1), 2003-10-02
mode.
RX=1, TX=1
RX=0, TX=0
registers.
in
the
After
RX=0
TX=0
status
RX=0, TX=0
FS Calib.
The
the
SmartRF
calibration is performed, the FS needs to
lock onto the right LO frequency. The
calibration and lock acquisition time is
given in the Electrical Specifications.
When the FS is in lock it is possible to go
into RX or TX mode. That can be done
either
command strobe registers, or by using the
RX and TX control pins. It is possible to
change quickly between TX and RX by
way of the FS On state.
Turning off RF can be accomplished by
either accessing the command strobe
register SRFOFF or by using the RX and
TX control pins. When using the RX and
TX pins to go from the FS On to Radio Off
it is important that TX is set to 0 before RX
is set to 0.
The state transitions using the RX and TX
pins are illustrated in Figure 14.
Lock achieved
by
accessing
FS On
RX=0
TX=0
RX
TX
®
CC2400
the
RX=1
TX=1
Page 31 of 73
SRX/STX