Datasheet
DS2148/DS21Q48
33 of 73
Table 4-5. Internal Rx Termination Select
RT1
(CCR5.1)
RT0
(CCR5.0)
INTERNAL RECEIVE
TERMINATION CONFIGURATION
0 0 Internal receive-side termination disabled
0 1
Internal receive-side 120Ω enabled
1 0
Internal receive-side 100Ω enabled
1 1
Internal receive-side 75Ω enabled
CCR6 (05H): COMMON CONTROL REGISTER 6
(MSB)
(LSB)
LLB RLB ARLBE ALB RJAB ECRS2 ECRS1 ECRS0
SYMBOL POSITION DESCRIPTION
LLB CCR6.7 Local Loopback. In Local Loopback (LLB), transmit data will be
looped back to the receive path passing through the jitter attenuator if it
is enabled. Data in the transmit path will act as normal. See Figure 1-1
and Section 6.2.2 for details.
0 = loopback disabled
1 = loopback enabled
RLB CCR6.6 Remote Loopback. In Remote Loopback (RLB), data output from the
clock/data recovery circuitry will be looped back to the transmit path
passing through the jitter attenuator if it is enabled. Data in the receive
path will act as normal while data presented at TPOS and TNEG will be
ignored. See Figure 1-1 and Section 6.2.1 for details.
0 = loopback disabled
1 = loopback enabled
ARLBE CCR6.5 Automatic Remote Loopback Enable and Reset. When this bit is set
high, the device will automatically go into remote loopback when it
detects loop-up code programmed into the receive loop-up code
definition registers (RUPCD1 and RUPCD2) for a minimum of 5
seconds and it will also set the RIR2.1 status bit. Once in a RLB state, it
will remain in this state until it has detected the loop code programmed
into the receive loop-down code definition registers (RDNCD1 and
RDNCD2) for a minimum of 5 seconds at which point it will force the
device out of RLB and clear RIR2.1. Toggling this bit from a 1 to a 0
can reset the automatic RLB circuitry. The action of the automatic
remote loopback circuitry is logically ORed with the RLB (CCR6.6)
control bit (i.e., either one can cause a RLB to occur).
ALB CCR6.4 Analog Loopback. In analog loopback (ALB), signals at TTIP and
TRING will be internally connected to RTIP and RRING. The incoming
signals, from the line, at RTIP and RRING will be ignored. The signals
at TTIP and TRING will be transmitted as normal. See Figure 1-1
and
Section 6.2.3
for more details.
0 = loopback disabled
1 = loopback enabled