CC2430 Datasheet, PDF (183/234 Pages) Texas Instruments – A True System-on-Chip solution for 2.4 GHz IEEE 802.15.4 / ZigBee-TM

CC2430
14.26 Frequency and Channel
Programming
The operating frequency is set by
programming the 10 bit frequency word
located in FSCTRLH.FREQ[9:8] and
FSCTRLL.FREQ[7:0]. The operating
frequency F_C in MHz is given by:
F_C = 2048 + FREQ[9:0] MHz
where FREQ[9:0] is the value given by
FSCTRLH.FREQ[9:8]:FSCTRLL.FREQ[7
:0]
In receive mode the actual LO frequency
is F_C – 2 MHz, since a 2 MHz IF is used.
Direct conversion is used for transmission,
14.27 VCO and PLL Self-Calibration
14.27.1 VCO
The VCO is completely integrated and
operates at 4800 – 4966 MHz. The VCO
frequency is divided by 2 to generate
frequencies in the desired band (2400-
2483.5 MHz).
14.27.2 PLL self-calibration
The VCO's characteristics will vary with
temperature, changes in supply voltages,
and the desired operating frequency.
In order to ensure reliable operation the
VCO’s bias current and tuning range are
so here the LO frequency equals F_C. The
2 MHz IF is automatically set by CC2430,
so the frequency programming is equal for
RX and TX.
IEEE 802.15.4 specifies 16 channels
within the 2.4 GHz band, numbered 11
through 26. The RF frequency of channel
k is given by [1] :
F_C = 2405 + 5 (k-11) MHz, k=11, 12, ..., 26
For operation in channel k, the
FSCTRLH.FREQ:FSCTRLL.FREQ register
should therefore be set to:
FSCTRLH.FREQ:FSCTRLL.FREQ = 357 +
5 (k-11)
automatically calibrated every time the RX
mode or TX mode is enabled, i.e. in the
RX_CALIBRATE, TX_CALIBRATE and
TX_ACK_CALIBRATE control states in
Figure 52 on page 180.
14.28 Output Power Programming
The RF output power of the device is
programmable and is controlled by the
TXCTRLL.PA_LEVEL RF register. Table
43 shows the output power for different
settings, including the complete
programming of the TXCTRLL control
register and the current consumption in
the radio itself.
PA_LEVEL
31
27
23
19
15
11
7
3
TXCTRLL
register
0xFF
0xFB
0xF7
0xF3
0xEF
0xEB
0xE7
0xE3
Output Power
[dBm]
0
-1
-3
-5
-7
-10
-15
-25
Current
consumption [mA]
17.4
16.5
15.2
13.9
12.5
11.2
9.9
8.5
Table 43: Output power settings
CC2430 PRELIMINARY Data Sheet (rev. 1.03) SWRS036A
Page 183 of 232