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DS3171/DS3172/DS3173/DS3174
136
bit must be set high for a minimum of 100ns and then set back low. This software bit is logically ORed with the
inverted hardware signal
RST
and the
0 = Normal operation
1 = Force all internal registers to their default values
Register Name:
PORT.CR2
Register Description:
Port Control Register 2
Register Address:
(0,2,4,6)42h
Bit
# 15 14 13 12 11 10 9 8
Name TLEN TTS RMON TLBO
RESERVED
LM2 LM1 LM0
Default
0 0 0 0 0 0 0 0
Bit
# 7 6 5 4 3 2 1 0
Name
RESERVED
RESERVED
FM2 FM1 FM0
RESERVED RESERVED
RESERVED
Default
0 0 0 0 0 0 0 0
Bit 15: Transmit Line IO Signal Enable (TLEN).
This bit is used to enable to transmit line interface output pins
TLCLKn, TPOSn/TDATn and TNEGn.
0 = Disable, force outputs low
1 = Enable normal operation
Bit 14: Transmit LIU Tri-State (TTS)
This bit is used to tri-state the transmit TXPn and TXNn pins. The LIU is still
powered up when the pins are tri-stated. It has no effect when the LIU is disabled and powered down.
0 = TXPn and TXNn driven
1 = TXPn and TXNn tri-stated
Bit 13: Receive LIU Monitor Mode (RMON)
This bit is used to enable the receive LIU monitor mode pre-amplifier.
Enabling the pre-amplifier adds about 20 dB of linear amplification for use in monitor applications where the signal
has been reduced 20 dB using resistive attenuator circuits.
0 = Disable the 20 dB pre-amp
1 = Enable the 20 dB pre-amp
Bit 12: Transmit LIU LBO (TLBO)
This bit is used enable the transmit LBO circuit which causes the transmit
signal to have a wave shape that approximates about 225 feet of cable. This is used to reduce near end crosstalk
when the cable lengths are short. This signal is only valid in DS3 LIU mode.
0 = TXPn and TXNn have full amplitude signals
1 = TXPn and TXNn signals approximate 225 feet of cable
Bits 10 to 8: Port Interface Mode (LM[2:0]).
The
LM[2:0]
bits select main port interface operational modes. The
default state disables the LIU and the JA. See Table 10-26.
Bits 5 to 3: Framing Mode (FM[2:0]).
The FM[2:0] bits select main framing operational modes. Default: DS3 C-bit.
See