FRS Signalling Processor
CMX882
CONTENTS
Section
Page
1.0
1.1
1.2
1.3
1.4
Features........................................................................................................................2
Brief Description............................................................................................................2
Block Diagram...............................................................................................................8
Signal List .....................................................................................................................9
External Components..................................................................................................11
1.4.1 PCB Layout Guidelines and Power Supply Decoupling ...................................12
1.4.2 Modulator Outputs ..........................................................................................13
General Description.....................................................................................................14
1.5.1 Sleep Mode and Auto Start Up........................................................................16
1.5.2 Auxiliary ADC .................................................................................................16
1.5.3 Receive Mode.................................................................................................17
1.5.4 Transmit Mode................................................................................................25
1.5.5 FFSK/MSK Data Packeting.............................................................................29
1.5.6 XTCSS Coding................................................................................................32
1.5.7 C-BUS Operation............................................................................................34
C-BUS Register Description ........................................................................................35
Application Notes ........................................................................................................57
1.7.1 CRC and FEC encoding information ...............................................................57
1.7.2 Data Interleaving.............................................................................................58
1.7.3 Scrambler Seed Transfer................................................................................58
Performance Specification...........................................................................................59
1.8.1 Electrical Performance....................................................................................59
1.8.2 Packaging.......................................................................................................69
1.5
1.6
1.7
1.8
Table
Page
Table 1 Voice Processing Combinations ................................................................................... 15
Table 2 Concurrent Rx Signalling Modes Supported by the CMX882 ....................................... 17
Table 3 CTCSS Tones............................................................................................................. 20
Table 4 DCS Modulation Modes............................................................................................... 21
Table 5 DCS 23 Bit Codes ....................................................................................................... 22
Table 6 In-band Tones............................................................................................................. 23
Table 7 Concurrent Tx Modes Supported by the CMX882........................................................ 25
Table 8 Data Frequencies for each Baud Rate......................................................................... 29
Table 9 Maximum Data Transfer Latency................................................................................. 32
Figure
Page
Figure 1 Block Diagram .............................................................................................................8
Figure 2 Recommended External Components........................................................................ 11
Figure 3 Power Supply Connections and De-coupling .............................................................. 12
Figure 4 Modulator output components to achieve -100dB/decade roll-off................................ 13
Figure 5 Rx Audio Filter Frequency Response ......................................................................... 18
Figure 6 De-emphasis Curve for TIA/EIA-603 Compliance....................................................... 18
Figure 7 Low Pass Sub-Audio Band Filter for CTCSS and DCS ............................................... 19
2004 CML Microsystems Plc
6
D/882/7
CMLMICRO [ CML MICROCIRCUITS ]
