Features .......................................................................................................................................................................... 1-4
1.3.1
General Modem Features ............................................................................................................................... 1-4
General Description ........................................................................................................................................ 1-5
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
CX20442 VC Hardware Pins and Signals (S Models) ................................................................................................... 3-17
3.2.1
CX20442 VC Signal Summary...................................................................................................................... 3-17
CX20442 VC Pin Assignments and Signal Definitions.................................................................................. 3-18
Electrical and Environmental Specifications ................................................................................................................. 3-24
3.3.1
Operating Conditions, Absolute Maximum Ratings, and Power Requirements ........................................... 3-24
Interface and Timing Waveforms ................................................................................................................................. 3-26
3.4.1
External Memory Bus Timing ....................................................................................................................... 3-26
3.4.2
Parallel Host Bus Timing .............................................................................................................................. 3-28
3.4.3
Serial DTE Interface...................................................................................................................................... 3-30
Register Signal Definitions ............................................................................................................................................. 5-3
Receiver Data Available Interrupt ................................................................................................................. 5-10
5.3.2
Receiver Character Timeout Interrupts ........................................................................................................ 5-11