Rainbow Electronics DS31256 - Manual (Page 54)

DS31256
54 of 181
Bits 8 to 15/Transmit DS0 Data (TDATA). This register holds the most current DS0 byte transmitted. It is used
by the receive side Layer 1 state machine when channelized local loopback (CLLB) is enabled.
Register Name:
R[n]CFG[j] where n = 0 to 15 for each port and j = 0 to 127 for each DS0
Register Description: Receive Layer 1 Configuration Register
Register Address:
Indirect Access through CP[n]RD
Bit # 7 6 5 4 3 2 1 0
Name RCH#(8): Receive HDLC Channel Number
Default
Bit # 15 14 13 12 11 10 9 8
Name RCHEN RBERT n/a RV54 n/a CLLB n/a R56
Default
Note: Bits that are underlined are read-only; all other bits are read-write.
Bits 0 to 7/Receive Channel Number (RCH#). The CPU loads the number of the HDLC channels associated
with this particular DS0 channel. If the port is running in an unchannelized mode (RUEN = 1), the HDLC channel
number only needs to be loaded into R[n]CFG0. If the fast (52Mbps) HDLC engine is enabled on port 0, HDLC
channel 1 is assigned to it and, likewise, HDLC channel 2 is assigned to the fast HDLC engine on port 2, if it is
enabled. Therefore, these HDLC channel numbers should not be used if the fast HDLC engines are enabled.
00000000 (00h) = HDLC channel number 1 (also used for the fast HDLC engine on port 0)
00000001 (01h) = HDLC channel number 2 (also used for the fast HDLC engine on port 1)
00000010 (02h) = HDLC channel number 3 (also used for the fast HDLC engine on port 2)
00000011 (03h) = HDLC channel number 4
11111111 (FFh) = HDLC channel number 256
Bit 8/Receive 56kbps (R56). If the port is running a channelized application, this bit determines whether the LSB
of each DS0 should be processed or not. If this bit is set, the LSB of each DS0 channel is not routed to the HDLC
controller (or the BERT, if it has been enabled through the RBERT bit). This bit does not affect the operation of
the V.54 detector. It always searches on all 8 bits in the DS0.
0 = 64kbps (use all 8 bits in the DS0)
1 = 56kbps (use only the first 7 bits received in the DS0)
Bit 10/Channelized Local Loopback Enable (CLLB). Enabling this loopback forces the transmit data to replace
the receive data. This bit must be set for each and every DS0 channel that is to be looped back. In order for the
loopback to become active, the DS0 channel must be enabled (RCHEN = 1) and the DS0 channel must be set into
the 64kbps mode (R56 = 0).
0 = loopback disabled
1 = loopback enabled
Bit 12/Receive V.54 Enable (RV54E). If this bit is cleared, this DS0 channel is not examined to check if the V.54
loop pattern is present. If set, the DS0 is examined for the V.54 loop pattern. When searching for the V.54 pattern
within a DS0 channel, all 8 bits of the DS0 channel are examined, regardless of how the DS0 channel is
configured (i.e., 64k or 56k).
0 = do not examine this DS0 channel for the V.54 loop pattern
1 = examine this DS0 channel for the V.54 loop pattern
Bit 14/Route Data Into BERT (RBERT). Setting this bit routes the DS0 data into the BERT function. If the DS0
channel has been configured for 56kbps operation (R56 = 1), the LSB of each DS0 channel is not routed to the
BERT block. In order for the data to make it to the BERT block, the host must also configure the BERT for the
proper port through the master control register (Section
5 ).
0 = do not route data to BERT
1 = route data to BERT