XE2420G Просмотр технического описания (PDF) - Unspecified

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XE2420G

Smallest World-Wide 2400 BPS Modem

Unspecified 

XE2420G Special Features

The XE2420G includes special features which will be

highly valuable for some applications. These features

include Error Correction, Power Down Mode, Handset

Interrupt, and Caller ID Decoding.

Error Correction:

The XE2420G incorporates V.42 error correction. V.42 error

correction incoprorates two error Correction Schemes,

LAPM and MNP. Either of these portocols can correct

99% of the errors which could occur in the data stream

during normal transmission due to noise and line hits on

teh telephone line. Error correction is controlled with the

AT/N command.

Power Down Mode:

The primary circuits of the XE2420G can be shut down

by a single command from the host, reducing power

consumption to less than 50 microamps. This makes the

XE2420G ideal for battery powered applications. Issuing

the AT:U65,20E0<CR> command shuts down the

XE2420G’s modem controller and analog front end. The

XE2420G can be restored to normal operation by

activating the modem’s RESET signal on Pin 3. The

XE2420G will be fully awakenend a minimum of 300

milliseconds after RESET is applied.

Handset Interrupt:

The XE2420G constantly monitors the telephone line’s

DC loop voltage and current. When a change is detected

in the electrical characteristcs of the telephone line, the

XE2420G activates the /INT output, Pin 13.

Upon detection of the interrupt the application host can

read User Register U70 to determine teh source of the

interrupt. Bit 2 of that register indicates that a parallel

handset has been detected. The application host can

then intiate a disconnect to permit the handset to be

used.

The Handset Interrupt feature prevents equipment,

which shares the telephone line with a standard handset,

such as a residential electrical meter, from blocking

emergency calls.

Caller ID Decoding:

The XE2420G can detect and pass Caller ID information

to the local system host. Detection of the Caller ID

information allows the application to answer calls from

only known sources. When a Caller ID signal is received,

the XE2420G provides the “CIDM” response to the host

to acknowledge that Caller ID information is being

detected. The modem’s Interrupt Register, U70, can also

be set to create an interrupt when Caller ID is detected.

The XE2420G decodes and passes the Caller ID characters

to the application host as they are received and provides

the “NO CARRIER” response to indicate when the Caller

ID message is complete. The XE2420G now resumes

monitoring the incoming Ring signal. If the calling number

is recognized by the application host, it can initiate a

connection using the ATA command.

XECOM

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XE2420G

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