AN93
Rev. 1.4
125
Bits 8:0 (OHT) set the delay between the time the modem goes off-hook and LVCS or LCS is read for an
overcurrent condition. The default value for this register is 30 ms (see Table 86).
U78 is a bit-mapped register that controls intrusion detection blocking and intrusion suspend. U78 resets to 0x0000
with a power-on or manual reset (see Table 87).
Bits 15:14 (IB) controls intrusion blocking after dialing has begun. Table 87 defines the bit values and intrusion
blocking.
Bits 7:0 (IS) set the delay between the start of dialing and the start of the intrusion algorithm when IB = 10
(see
Table 87).
U79 is a bit-mapped register. Bits 15:6 are reserved.
Bits 5:0 represent the line voltage, loop current, or on-hook line monitor (see Table 88). While the modem is on-
hook, the value in the LVCS register measures loop voltage (see Table 89). This value can be used to determine if
a line is connected or if a parallel phone or other device goes off-hook or on-hook. The accuracy of the LVCS bits is
±20%. When the modem goes off-hook, the value in the LVCS register measures loop current. LVCS can indicate
when a parallel phone or other device goes on-hook or off-hook and detect whether enough loop current is
available for the modem to operate or if an overload condition exists.
The line voltage monitor full scale may be modified by changing R5 as follows:
V
MAX
= V
MIN
+ 4.2 x (10 M
Ω
+ R5 + 1.78 k
Ω
) / (R5 + 1.78 k
Ω
) / 5
See Table 89. LVCS is backward-compatible with older ISOmodem revisions. The value is absolute and does not
reflect loop polarity. See U6C (LVS) [15:8] for 1 V/bit resolution and signed, two’s complement format and
U63 (LCS) [15:8] for 1.1 mA/bit loop current measurement. The values for loop voltage and loop current in U79 are
calculated by the modem from the values in U6C and U63 respectively.
Table 86. U77 Bit Map
Bit
Name
Function
15:12
IST
Intrusion Settling Time (250 ms units) 1 second default.
11
HOI
Hang-Up On Intrusion.
0
=
ISOmodem does not automatically hang up after an off-hook PPD interrupt.
1 = ISOmodem automatically hangs up after an off-hook PPD interrupt.
10
Reserved
Read returns zero.
9
AOC
AutoOvercurrent. Should be set for normal operation.
0
=
Disable.
1 = Enable.
8:0
OHT[8:0]
Off-Hook Time (1 ms units) 30 ms default.
Table 87. U78 Bit Map
Bit
Name
Function
15:14
IB
Intrusion Blocking.
00
=
No intrusion blocking.
01 = Intrusion disabled from start of dial to end of dial.
10 = Intrusion disabled from start of dial to IS register time-out.
11 = Intrusion disabled from start of dial to CONNECT XXX, NO DIALTONE, or
NO CARRIER
13:8
Reserved
Read returns zero.
7:0
IS
Intrusion Suspend (500 ms units) default = 0 ms.
Содержание Si2404
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Страница 200: ...AN93 200 Rev 1 4 Figure 31 TAM Handset and Speakerphone Voice Paths ...
Страница 201: ...AN93 Rev 1 4 201 Figure 32 Si3000 Codec Gain and Signal Selection Options ...
Страница 290: ...AN93 290 Rev 1 4 Figure 57 256 Band Spectral Display Figure 58 2048 Band Spectral Display ...
Страница 305: ...AN93 Rev 1 4 305 Figure 76 Parallel or SPI Port Interrupt Service Flowchart ...