am79c30a Advanced Micro Devices, am79c30a Datasheet - Page 22

• Manufacturer Part Number: am79c30a
• Description: Digital Subscriber Controller ?dsc ?circuit
• Manufacturer: Advanced Micro Devices

Therefore, in this example, MCR1 provides a data link
from the S Interface and MCR2 sets up a voice connec-
tion across the S Interface.
To loopback a channel, the same channel code is used
for port 1 and port 2. For example, to loopback B1, B2,
and Ba, the MCRs would be:
MCR3 has higher priority than MCR2. MCR2 has
higher priority than MCR1.
If multiple connections are made to the same port, the
data from the connecting ports in the highest priority
22
Register 7 6 5 4 3 2 1 0 Channel Connection
MCR1
MCR2
MCR3
0 0 0 1 0 0 0 1 B1 (LIU) Loopback
0 0 1 0 0 0 1 0 B2 (LIU) Loopback
0 0 1 1 0 0 1 1 Ba (MAP) Loopback
Port 1
MPI
Port 2
Bb
Bc
Figure 2. MUX Logical Channels
Bd
Am79C30A/32A Data Sheet
Peripheral Port
B-channel
Ba MAP
MUX
Be
MCR will overwrite the data from the connecting port in
the lower priority MCR, for example:
The final data transfers are:
Therefore, the data transfer from B1 (LIU) to Bb (MPI)
is lost in the arrangement proposed in MCR2.
Register 7 6 5 4 3 2 1 0 Channel Connection
MCR1
MCR2
MCR3
B1 (LIU) receives Bb (MPI),
Ba (MAP) receives Bb (MPI),
Bb (MPI) receives Ba (MAP).
Bf
0 0 0 0 0 0 0 0 No connect
0 0 0 1 0 1 0 0 B1 (LIU)
0 1 0 0 0 0 1 1 Bb (MPI)
Port 1
Port 2
B1
B2
LIU
09893H-3
Ba (MAP)
Bb (MPI)