CMX138 CML Microcircuits, CMX138 Datasheet - Page 48

• Manufacturer Part Number: CMX138
• Description: Audio Scrambler and Sub-Audio Signalling Processor
• Manufacturer: CML Microcircuits

Audio Scrambler and Sub-Audio Signalling Processor
b3
b2
b1
b0
Bits 2 to 15 of the Status register are cleared to '0' after the Status register is read. Detection of the DCS
turn off tone and removal of the DCS code are both flagged as DCS events in the Status register, not as
CTCSS events.
The data in this register is not valid if bit 5 of the Power Down Control register, $C0 is set to 1.
9.1.16 Programming Register – $C8 write
See section 9.2 for a definition of programming block operation.
9.1.17 Scrambler Inversion Frequency – $CB write
Bits 13-0 set the inversion frequency of the audio scrambler. By default this is set to 3300Hz with the
value $2333. The value of this field can be calculated by: V= ( f
Other common values are:
Note that this register can be changed whilst in Rx or Tx mode.
9.1.18 Tone Status - $CC read
This word holds the current status of the CMX138 sub-audio and In-band tone sections. This word should
be read by the host after an interrupt caused by a DCS, CTCSS or In-band tone event. In Tx mode this
register will be cleared to '0'.
b15-11 Detected In-band frequency; identifies the frequency by its position in Table 5 In-band Tone. A
b10-8 reserved
b7–0
© 2008 CML Microsystems Plc
15
15
15
0
Program Block Address
reserved
reserved
reserved
Program Register Ready
14
change in the state of bits 15 to 11 will cause bit 13 of the Status register ($C6), ‘In-band State
Change’, to be set to '1'.
Detected DCS or CTCSS code, identifies the detected sub-audio tone by its position in
DCS Codes and CTCSS
14
14
Tone Detected
0
When set to 1, this bit indicates that the Program Register, $C8 is available for the host to write
to it. Cleared by writing to the Programming Register, $C8.
13
13
13
12
12
12
11
11
11
Tones.
10
x
10
10
3000
3100
3200
3300
3400
f
inv
9
x
9
9
$CB register (hex)
Scrambler Inversion Frequency
8
x
Page 48
8
8
2000
2111
2222
2333
2444
7
7
7
Program Block Data
inv
6
6
6
default
/ 0.7324 ) *2.
Detected DCS or CTCSS code
5
5
5
4
4
4
3
3
3
2
2
2
D/138_FI1.0/5
1
1
1
Table 2
CMX138
0
0
0