RALCWI Vocoder
CMX608/CMX618/CMX638
CONTENTS
Section
Page
1. Brief Description..................................................................................................................... 1
2. Block Diagram......................................................................................................................... 5
3. Signal List................................................................................................................................ 6
4. External Components............................................................................................................. 9
4.1. PCB Layout Guidelines and Power Supply Decoupling................................................. 11
4.2. Audio CODEC External Components (CMX618/CMX638 only).................................... 12
5. General Description.............................................................................................................. 13
5.1. Initialisation .................................................................................................................... 14
5.2. Encoder.......................................................................................................................... 15
5.2.1. Single Frame Packet, without FEC, STD or DTMF.............................................. 15
5.2.2. Multiple Frame Packet with FEC, but without STD or DTMF............................... 16
5.3. Decoder ......................................................................................................................... 16
5.3.1. Single Frame Packet, without FEC, STD or DTMF.............................................. 17
5.3.2. Multiple Frame Packet with FEC, but without STD or DTMF............................... 19
5.4. Overall Signal Latency................................................................................................... 20
5.5. Vocoder Data Format and Bit Order.............................................................................. 20
5.5.1. Packets of Raw Vocoder Frames ........................................................................ 20
5.5.2. Packets of FEC Protected Frames ...................................................................... 22
5.6. External CODEC Support .............................................................................................. 23
5.7. Operation with DTMF (Dual Tone Multi-Frequency)...................................................... 26
5.7.1. DTMF Transmit .................................................................................................... 26
5.7.2. DTMF Receive ..................................................................................................... 26
5.7.3. DTMF Format....................................................................................................... 27
5.8. Operation with STD (Single Tones) ............................................................................... 28
5.9. C-BUS Interface............................................................................................................. 29
5.10. C-BUS Registers............................................................................................................ 32
5.10.1. Command Registers ............................................................................................ 32
5.10.2. 8 Bit Write-Only Registers.................................................................................... 33
5.10.3. 8 Bit Read-Only Registers.................................................................................... 44
5.10.4. 16-bit Write-Only Registers.................................................................................. 46
5.10.5. 16-bit Read-Only Registers.................................................................................. 51
6. Application Notes.................................................................................................................. 55
6.1. Basic Operation of the Vocoder..................................................................................... 55
6.2. FEC and LLR Decoding................................................................................................. 57
6.3. DTX and SID Functions ................................................................................................. 57
6.4. Single Tone Transfer ..................................................................................................... 57
6.5. Slip Management........................................................................................................... 57
6.6. Setting the Watermarks for the Vocoder Data Input (Output) FIFOs ............................ 59
6.7. Download Protocol for Function Images™ .................................................................... 59
6.8. Using the PLEVEL register to set the Input Gain........................................................... 60
7. Performance Specification................................................................................................... 61
7.1. Electrical Performance................................................................................................... 61
7.1.1. Absolute Maximum Ratings ................................................................................. 61
7.1.2. Operating Limits ................................................................................................... 61
7.1.3. Operating Characteristics..................................................................................... 62
7.2. Packaging ...................................................................................................................... 68
2014 CML Microsystems Plc
3
D/608_18_38/11
CMLMICRO [ CML MICROCIRCUITS ]
