Rainbow Electronics DS2154 - Manual (Page 23)

DS2154
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RCLA CCR3.0 Receive Carrier Loss (RCL) Alternate Criteria.
0=RCL declared upon 255 consecutive zeros (125 us)
1=RCL declared upon 2048 consecutive zeros (1 ms)
POWER–UP SEQUENCE
On power–up, after the supplies are stable, the DS2154
should be configured for operation by writing to all of the
internal registers (this includes the Test Registers) since
the contents of the internal registers cannot be pre-
dicted on power–up. Next, the LIRST (CCR5.7) bit
should be toggled from zero to one to reset the line inter-
face circuitry (it will take the DS2154 about 40 ms to
recover from the LIRST bit being toggled). Finally, after
the RSYSCLK and TSYSCLK inputs are stable, the
ESR bit should be toggled from a zero to a one and then
back to zero (this step can be skipped if the elastic
stores are not being used). Both TCLK and RCLKI must
be present for the parallel control port to operate prop-
erly.
CCR4: COMMON CONTROL REGISTER 4 (Address=A8 Hex)
(MSB) (LSB)
RLB LLB LIAIS TCM4 TCM3 TCM2 TCM1 TCM0
SYMBOL POSITION NAME AND DESCRIPTION
RLB CCR4.7 Remote Loopback.
0=loopback disabled
1= loopback enabled
LLB CCR4.6 Local Loopback.
0=loopback disabled
1=loopback enabled
LIAIS CCR4.5 Line Interface AIS Generation Enable. See Figure 1–1 for details.
0=allow normal data from TPOSI/TNEGI to be transmitted at TTIP and
TRING
1=force unframed all ones to be transmitted at TTIP and TRING
TCM4 CCR4.4 Transmit Channel Monitor Bit 4. MSB of a channel decode that deter-
mines which transmit channel data will appear in the TDS0M register. See
Section 6 for details.
TCM3 CCR4.3 Transmit Channel Monitor Bit 3.
TCM2 CCR4.2 Transmit Channel Monitor Bit 2.
TCM1 CCR4.1 Transmit Channel Monitor Bit 1.
TCM0 CCR4.0 Transmit Channel Monitor Bit 0. LSB of the channel decode.
REMOTE LOOPBACK
When CCR4.7 is set to a one, the DS2154 will be forced
into Remote LoopBack (RLB). In this loopback, data
input via the RPOSI and RNEGI pins will be transmitted
back to the TPOSO and TNEGO pins. Data will con-
tinue to pass through the receive side framer of the
DS2154 as it would normally and the data from the
transmit side formatter will be ignored. Please see
Figure 1–1 for more details. LOCAL LOOPBACK
When CCR4.6 is set to a one, the DS2154 will be forced
into Local LoopBack (LLB). In this loopback, data will
continue to be transmitted as normal through the trans-
mit side of the DS2154. Data being received at RTIP
and RRING will be replaced with the data being trans-
mitted. Data in this loopback will pass through the jitter
attenuator. Please see Figure 1–1 for more details.