CIRCC Ver la hoja de datos (PDF) - SMSC -> Microchip
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CIRCC Datasheet PDF : 70 Pages
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Carrier Frequency Divider
The Carrier Frequency Divider register is used to
program the ASK carrier frequency for the
transmit modulator and receive detector (Figure
6). The divider is eight bits wide.
The input clock to the Carrier Frequency Divider
is 1.6MHz (48MHz ÷ 30). The relationship
between the divider value (CFD) and the carrier
frequency (Fc) is as follows:
CFD = (1.6MHz/Fc) - 1
For example, program the Carrier Frequency
Divider register with 41 ('29'Hex) for a 38kHz
carrier like for the NEC remote control frame
format: Fc = 38.095kHz. This is ~.25%
accuracy. Table 8 contains representative CFD
vs. Carrier Frequency relationships.
The Carrier Frequency range is 1.6MHz to
6.25kHz.
The carrier frequency encoder/decoder can be
defeated using the Carrier Off bit. When Carrier
Off is one, the transmitter outputs a non-
modulated SCE serial NRZ data stream at the
programmed bit rate; the receiver does not
attempt to demodulate a carrier from the
incoming serial data stream.
CFD
001
005
009
013
017
021
025
029
033
037
041
045
049
053
057
061
Table 8 - Representative Carrier Frequencies
Fc (kHz) CFD Fc (kHz) CFD Fc (kHz) CFD
800.000 065
24.242
129
12.308
193
266.667 069
22.857
133
11.940
197
160.000 073
21.622
137
11.594
201
114.286 077
20.513
141
11.268
205
88.889
081
19.512
145
10.959
209
72.727
085
18.605
149
10.667
213
61.538
089
17.778
153
10.390
217
53.333
093
17.021
157
10.127
221
47.059
097
16.327
161
9.877
225
42.105
101
15.686
165
9.639
229
38.095
105
15.094
169
9.412
233
34.783
109
14.545
173
9.195
237
32.000
113
14.035
177
8.989
241
29.630
117
13.559
181
8.791
245
27.586
121
13.115
185
8.602
249
25.806
125
12.698
189
8.421
253
Fc (kHz)
8.247
8.081
7.921
7.767
7.619
7.477
7.339
7.207
7.080
6.957
6.838
6.723
6.612
6.504
6.400
6.299
13
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