Specifications

AN93
Rev. 0.9 89
3.3.35. U6C (LVS)
U6C contains the line voltage status register, LVS, and
resets to 0xXX00. Bits 7:0 are reserved, and a read
returns zero.
3.3.36. Modem Control and Interface Registers
Modem Control and Interface registers include registers
U6E, U70–U73, and U76–U79. These are bit-mapped
registers that control functions including TX/RX gain,
clocking, I/O, PCM codecs, intrusion detection, and
LVCS (line voltage current sense).
Table 55. U68 Bit Map
Bit Name Function
15:8 Reserved Read returns zero.
7:3 Reserved Do not modify.
2BTEBilling Tone Protect Enable.
0
= Disabled.
1
= Enabled.
1ROVReceive Overload.
0
= Normal receive input level.
1
= Excessive receive input level.
0BTDBilling Tone Detected.
0
= No billing tone.
1
= Billing tone detected (cleared by writing 0).
Table 56. U6A Bit Map
Bit Name Function
15 Reserved Read returns zero.
14 SQ1 Spark quenching. See OHS2.
13 Reserved Read returns zero.
12 SQ0 Spark quenching. See OHS2.
11:3 Reserved Read returns zero.
2 OVL Overload Detected.
This bit has the same function as ROV, but clears itself after the overload has been removed.
This bit is only masked by the off-hook counter and is not affected by the BTE bit.
1 Reserved Read only; value indeterminate.
0 Reserved Read returns zero.