XE5692H Ver la hoja de datos (PDF) - Xecom

Número de pieza

componentes Descripción

Fabricante

XE5692H

Half-Size, Low-Cost Global Embedded Modem

Xecom 

XE5692H Shared Line Features

The XE5692H can monitor telephone line

conditions before, after and during calls. This

allows the system to avoid conflicts with other

equipment connected to the same telephone line.

There are two line monitoring modes; Connect

Detect and Handset Interrupt.

Connect Detect:

Connect Detect is active when the XE5692H is

on-hook. With AT%V2 selected the XE5692H

verifies the availability of the telephone line by

checking the DC loop voltage before going off-

hook for dialing or answering a call. The nominal

value of loop voltage is stored in register U85,

typically 48 volts. The XE5692H can detect either

the lack of an installed telephone line or that the

connected line is in use.

Handset Interrupt:

The Handset Interrupt feature permits the modem

to yield the telephone line to other equipment

connected to the same line. This prevents the

XE5692H from blocking outgoing emergency calls

when the line is shared as in a residential

application including set top boxes and automated

meter readers. For Handset Interrupt the modem

monitors the loop current while it is off-hook. The

Loop current will drop if a piece of equipment

connected to the same telephone line goes off-

hook. The Handset Interrupt function is controlled

by registers U77 and U78. U78 defines when the

Handset Interrupt is operable, and U77 allows the

operator to configure the modem to disconnect

immediately upon detecting another piece of

equipment on the telephone line.

NO LINE If the telephone line is disconnected

from the modem, the voltage on Tip and Ring will

be zero. If the modem reads a DC loop voltage of

3 volts or less, the modem will not go off-hook and

will issue the “NO LINE” response.

LINE IN USE If a telephone handset, fax

machine or other piece of equipment connected to

the telephone line is in use, the DC loop voltage

will drop. Typically the DC loop voltage will drop to

around 10 volts while the telephone line is in use. If

the modem sees a DC loop voltage between 3

volts and 85% of the nominal loop voltage (41

volts typical), the modem will not go off-hook but

will transmit the “LINE IN USE” response

If neither the “NO LINE” or “LINE IB USE”

conditions is true, the XE5692H goes off-hook and

completes the original command.

U77: Bit 11 of U77 sets the XE5692H to

automatically disconnect any time another piece of

equipment connects to the line while the modem is

off-hook. This configuration is recommended when

the modem will be sharing a line with a telephone

handset as it provides the quickest access to the

phone line for emergency calls. If U77 bit 11 is not

set, then U70 bit 10 should be. U70 bit 10 causes

the modem to provide an interrupt when the off-

hook condition of the other equipment is detected.

U78 Bits 14 and 15 of U78 control when the

Handset Interrupt will be active.

• If both bits are reset, Handset Interrupt is

disabled.

• If only bit 14 is set, the modem monitors the line

for a Handset Interrupt after dialing.

• If only bit 15 is set, the XE5692H activates

Handset Interrupt when the timer set by bits 0 to

7 expires. Bits 0-7 set this timer in 500

millisecond increments.

• If both bits 14 and 15 are set, the modem starts

monitoring for a Handset Interrupt after the

modem handshake is completed.

XECOM

(10)

XE5692H

Share Link: