MRF39RA Datasheet, PDF (14/72 Pages) Microchip Technology – Low-Power, Integrated UHF Receiver

MRF39RA
2.4.9 CORDIC
The Cordic task is to extract the phase and the
amplitude of the modulation vector (I + j.Q). The
following information is used, still in the digital domain:
• Phase output: used by the FSK demodulator and
the AFC blocks
• Amplitude output: used by the RSSI block for
FSK demodulation, AGC and automatic gain
calibration purposes.
Figure 2-5 shows the cordic extraction.
FIGURE 2-5:
CORDIC EXTRACTION
Real-Time
Magnitude
Q(t)
Real-Time Phase
I(t)
2.4.10 BIT RATE SETTING
The bit rate (BR) is controlled by the BitRate bits in
RegBitrate, as shown in Equation 2-6 below.
EQUATION 2-6: BIT RATE
BR = _B--^F---_i-^X-_t--_R^O----_a^S---^C_t--_e-
Table 2-5 lists some of the accessible bit rates.
TABLE 2-5: BIT RATE EXAMPLES
Type
BitRate
<15:8>
Classical Modem Baud Rates
(multiples of 1.2 kbps)
Classical Modem Baud Rates
(multiples of 0.9 kbps)
Round Bit Rates
(multiples of 12.5, 25 and 50 kbps)
Watch Xtal Frequency
0x68
0x34
0x1A
0x0D
0x06
0x03
0x01
0x00
0x02
0x01
0x0A
0x05
0x02
0x01
0x00
0x00
0x00
0x00
0x03
BitRate
<7:0>
0x2B
0x15
0x0B
0x05
0x83
0x41
0xA1
0xD0
0x2C
0x16
0x00
0x00
0x80
0x40
0xD5
0xA0
0x80
0x6B
0xD1
(G)FSK
(G)MSK
1.2 kbps
2.4 kbps
4.8 kbps
9.6 kbps
19.2 kbps
38.4 kbps
76.8 kbps
153.6 kbps
57.6 kbps
115.2 kbps
12.5 kbps
25 kbps
50 kbps
100 kbps
150 kbps
200 kbps
250 kbps
300 kbps
32.768 kbps
OOK
1.2 kbps
2.4 kbps
4.8 kbps
9.6 kbps
19.2 kbps
—
—
—
—
—
12.5 kbps
25 kbps
—
—
—
—
—
—
32.768 kbps
Actual BR (b/s)
1200.015
2400.060
4799.760
9600.960
19196.16
38415.36
76738.60
153846.1
57553.95
115107.9
12500.00
25000.00
50000.00
100000.0
150234.7
200000.0
250000.0
299065.4
32753.32
DS40001778B-page 14
 2015 Microchip Technology Inc.