XE2422H Просмотр технического описания (PDF) - Unspecified
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XE2422H Datasheet PDF : 20 Pages
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XE2422H Shared Line Features
The XE2422H monitors line conditions before, after,
and during calls. This allows conflicts with other
equipment connected to the telephone line to be
avoided. The XE2422H includes two Shared Line
Features; Connect Detect and Handset Interrupt.
Connect Detect
Register SDB stores the XE2422H on-hook
telephone line voltage. The modem checks the value
of register SDB before going off-hook to avoid
interrupting a call in progress. The typical value for
telephone line voltage while on-hook is 48 volts. A
lower voltage level indicates that the line is either
disconnected from the modem or is currently in use.
Register SDB is an 8 bit register. It stores the loop
voltage as a 2’s complement number with each bit
representing 1 volt. The Most Significant Bit
represents the polarity of the loop voltage.
Handset Interrupt:
Handset Interrupt permits the modem to yield the
phone line when other equipment on the line goes
off-hook. This prevents the modem from blocking
outgoing emergency calls when the telephone line is
shared as in residential use. The modem monitors
loop current while it is off-hook. The loop current
will drop if another device on the line goes off-hook.
Register SF3 holds the loop current value in 1.1
milliamp increments. The XE2422H updates SF3
regularly. The loop current value stored in SF3 is
compared to the values of registers S11 and S12. If
the value S12 is greater than the value of SF3 plus
S11, then the XE2422H assumes the equipment
connected to the telephone line has gone off-hook,
issues the Handset Interrupt response “i” and, if so
configured, issues an Interrupt to the host controller.
The host controller determines whether to terminate
the call and yield the line to the other equipment.
V.22/Bell 212 Fast Connect
The XE2422H supports Fast Connect algorithms for Bell 212 and V.22 operation. These reduce the
handshaking time required for faster transaction times in applications with small data loads. Nine Registers
are used to control the Fast Connect feature as shown in the chart below
Register
S1E
S1F
S20
S21
S22
S23
S24
S34
S35
Function
Transmit Answer Tone Length
Answer Tone to Transmit Delay
Unscrambled Ones Length (V.22)
Transmit Scrambled Ones Delay (V.22)
Transmit Scrambled Ones Length (V.22)
V.22/V.22b Data Delay Low
V.22/V.22b Data Delay High
Answer Tone Length (S1E =0x00)
Receive V.22 Scrambled Ones Length
Units
1s
5/3 ms
5/3 ms
53.3 ms
5/3 ms
5/3 ms
5/3 ms
5/3 ms
5/3 ms
Default
0x03
0x2D
0x5D
0x09
0xA2
0xCB
0x08
0x5A
0xA2
Fast
Connect
0x00
0x00
0x00
0x00
0x00
0x00
0x00
0xF0
0x00
XECOM
(8)
XE2422H
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