AN93
Rev. 1.4
123
U77 is a bit-mapped register that controls parameters relating to intrusion detection and overcurrent detection. U77
resets to 0x401E with a power-on or manual reset (see Table 86).
Bits 15:12 (IST) set the delay between the time the modem goes off-hook and the intrusion detection algorithm
begins. This register has 250 ms increments, and the default value is 4 (1 sec).
Bit 11 (HOI) determines whether the host or modem responds to an intrusion. HOI = 0 (default) prevents the
modem from hanging-up in response to an intrusion without host intervention. In this case, the host monitors
U70 [2] (PPD) and takes the appropriate action when PPD is asserted indicating an intrusion. If HOI = 1, the
modem hangs up immediately and will not go off-hook and dial when an intrusion is detected without host
intervention. If %V
N
commands are set, HOI also causes the LINE IN USE result code upon PPD interrupt.
Bit 9 (AOC) = 0b disables Auto Overcurrent. If enabled, the modem sets the DAA OPE bit to enable Auto
Overcurrent protection in the DAA. When LCS > 160 mA (or 60 mA in current limit mode), the DAA switches to
800
mode and sets the OPD bit. The modem then waits for 5 ms, clears the OPE bit to return to normal DC
termination mode and clears the OPD bit. The modem decrements an internal counter, N, which is initialized to the
value in U1DD. When N reaches 0 (indicating an overcurrent situation for an extended period of time), the modem
goes back on-hook. After one second, the modem goes off-hook again with the OPE bit set.
In the case where the OPD bit is set and LVS > 50 V, the modem forces N to a value of 4, if U1DD>4. This prevents
damage from a high voltage event, such as a power line cross. The counter, N, is reinitialized to U1DD value when
overcurrent is absent for 250 ms. See Figure 28 for a detailed description of the overcurrent protection operation.
Table 85. U76 Bit Map
Bit
Name
Function
15:9
OHSR
Off-Hook Sample Rate for Intrusion Detection (40 ms units).
(1 second default)
8
FACL
Force ACL.
0
=
While off-hook, ACL is automatically updated with LVCS value.
1 = While off-hook, ACL saves previously written value.
7:5
DCL
Differential Current Level (3 mA units, 6 mA default)
4:0
ACL
Absolute Current Level (3 mA units, 0 mA default)
Содержание Si2404
Страница 2: ...AN93 2 Rev 1 4 ...
Страница 27: ...AN93 Rev 1 4 27 Figure 7 Parallel Interface Read Timing Figure 8 Parallel Interface Write Timing ...
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 ...