Datasheet

MRF49XA

EQUATION 2-2:

W-1 W-0 W-1 W-0 W-0 W-1 W-1 W-0

CCB<15:12> FREQB<11:8>

bit 15 bit 8

W-1 W-0 W-0 W-0 W-0 W-0 W-0 W-0

FREQB<7:0>

bit 7 bit 0

Legend: r = reserved bit

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 15-12 CCB<15:12>: Command Code bits

The command code bits (1010b) are serially sent to the microcontroller to identify the bits to be written

in the CFSREG.

bit 11-0 FREQB<11:0>: Center Frequency Set bits

These bits set the center frequency to be used during transmit or receive. The 12-bit value (F

VAL) must

be in a decimal range of 96 to 3903. The value outside this range results in the previous value being

retained and used such that no frequency change occurs

(1)

Note 1: To calculate the center frequency (F0), use Equation 2-2 and the values from Tabl e 2 -5. The CFSREG

sets the frequency within the selected band for transmit or receive. Each band has a range of frequencies

available for changing channels or frequency hopping. The selectable frequencies for each band are given

in Table 2 - 6.

F0 = 10 x FA1 x (FA0 + FVAL/4000) MHz

where:

FVAL = Decimal Value of FREQB<11:0> = 96 < FVAL < 3903

Where FA0 and FA1 are constant values as given in Table 2-5 to calculate the Center Frequency.

TABLE 2-5: CENTER FREQUENCY VALUE

Range FA1 FA0

433 MHz 1 43

868 MHz 2 43

915 MHz 3 30

TABLE 2-6: FREQUENCY BAND TUNING RESOLUTION

Frequency Band (MHz) Min. (MHz) Max. (MHz) Tuning Resolution (kHz)

400 430.2400 439.7575 2.5

800 860.4800 879.5150 5.0

900 900.7200 929.2725 7.5