CMX808A Ver la hoja de datos (PDF) - MX-COM Inc
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CMX808A Datasheet PDF : 22 Pages
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Family Radio Service CTCSS Processor
11
CMX808A Preliminary Information
4.1.2.5 CTCSS RX PROGRAM Register (Hex address $84)
This is a 16-bit register. Byte (1) is sent first. The two bytes are used to program the center frequencies of up
to 7 tones in the sub-audio band that will be decoded by the receiver.
Each tone is identified by its address in Bits 6, 5 and 4 of byte (1). The remaining 12 bits contain the data
representing the tone frequency according to the formula below. If a tone is not required, the 12 bits should
be set to zero.
Byte 1
Byte 2
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
0
0
0
0
0
0
0
1
0
0
1
0
0
0
1
1
0
1
0
0
0
1
0
1
0
1
1
0
<----------------------- N ----------------------->
N is the binary representation of the
following decimal number (n):
n
=
INT
948982 × fTONE
f XTAL
<----------------------- R ----------------------->
R is the nearest 6-bit binary
representation of (r), where:
r
=
237245
f XTAL
−
4×
n
fTONE
×
8400
Example: To program 100Hz when using the recommended 4.0MHz Xtal.
n
=
INT
948982 × 100
4.0 × 106
n = INT(23.72) = 23
∴ N = 010111(binary)
r
=
237245
4.0 × 106
−
4
23
× 100
×
8400
r = 15.21(round up if exactly halfway)
r = 15
∴ R = 001111(binary)
Therefore the 12-bit code is 010111001111.
The Hex address represented by Bits 6, 5 and 4 in byte (1) is used as the code to indicate which tone has
been decoded. This code appears in Bits 2, 1 and 0 of the SUB-AUDIO STATUS register $81. The seven
programmed tones use Hex addresses $0 - $6. Address $7 should not be used.
4.1.2.6 TONE CLONING (Hex Address $9C)
This register enables and disables tone cloning as shown below:
$9C = $01 enables tone cloning
$9C = $00 disables tone cloning
The Tone Cloning Routine is shown in Figure 4.
©1999 MX-COM, Inc.
www.mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054
Doc. # 20480199.002
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA
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