Features .......................................................................................................................................................................... 1-4
1.3.1
General Modem Features................................................................................................................................ 1-4
1.3.2
SmartDAA Features ........................................................................................................................................ 1-5
General Description ........................................................................................................................................ 1-6
Digital Isolation Barrier................................................................................................................................. 1-10
1.5.3
CX20493 SmartDAA Line Side Device.......................................................................................................... 1-10
AT Commands .............................................................................................................................................................. 1-10
Serial DTE Interface Operation........................................................................................................................................ 2-1
Telephone Number Directory.......................................................................................................................... 2-2
Call Progress Tone Detection ......................................................................................................................... 2-2
2.3.5
Answer Tone Detection................................................................................................................................... 2-2
2.3.6
Ring Detection................................................................................................................................................ 2-2
Data Mode ...................................................................................................................................................................... 2-4
Flow Control ................................................................................................................................................... 2-4
Telephone Line Monitoring............................................................................................................................. 2-4
2.4.6
Fall Forward/Fallback (V.92/V.90/V.34/V.32 bis/V.32) ................................................................................... 2-4
Error Correction and Data Compression......................................................................................................................... 2-6
V.44 Data Compression.................................................................................................................................. 2-6
2.6.4
V.42 bis Data Compression ............................................................................................................................ 2-6
2.6.5
MNP 5 Data Compression .............................................................................................................................. 2-7
Line In Use Detection ..................................................................................................................................... 2-7
Fax Class 1 and Fax Class 1.0 Operation ........................................................................................................................ 2-8
Point-of-Sales Support ................................................................................................................................................... 2-8
Tone Detectors ............................................................................................................................................... 2-9
V.80 Synchronous Access Mode (SAM) - Video Conferencing...................................................................................... 2-9
Full-Duplex Speakerphone (FDSP) Mode (S Models)................................................................................................... 2-10
Caller ID ........................................................................................................................................................................ 2-10
Worldwide Country Support ......................................................................................................................................... 2-10
Power On Reset Tests .................................................................................................................................. 2-11
Low Power Sleep Mode ................................................................................................................................................ 2-12
CX81801 Modem Hardware Pins and Signals ................................................................................................................ 3-1
3.1.1
Common to Parallel and Serial Interface Configurations................................................................................ 3-1
Serial Interface Configuration Only................................................................................................................. 3-2
3.1.2.1
Serial DTE Interface and Indicator Outputs (PARIF = Low)........................................................ 3-2
3.1.3
Parallel Interface Configuration Only (PARIF = High)..................................................................................... 3-3
3.1.3.1
Parallel Host Bus Interface ......................................................................................................... 3-3
Telephone Line Interface .......................................................................................................... 3-22
3.2.1.3
Voltage References................................................................................................................... 3-22
3.2.1.4
General Purpose Input/Output.................................................................................................. 3-23
3.2.1.5
No Connects ............................................................................................................................. 3-23
3.2.2
CX20493 LSD Pin Assignments and Signal Definitions ............................................................................... 3-23
CX20442 VC Hardware Pins and Signals (S Models)................................................................................................... 3-28
3.3.1
CX20442 VC Signal Summary...................................................................................................................... 3-28
Register Signal Definitions ............................................................................................................................................. 5-3
Receiver Data Available Interrupt ................................................................................................................. 5-10
5.3.2
Receiver Character Timeout Interrupts......................................................................................................... 5-11