104
Agere Systems Inc.
Data Sheet
May 2001
and Packet Payload Engine
Ambassador T8110 PCI-Based H.100/H.110 Switch
10 Stream Rate Control
(continued)
10.2.2 L-Bus 16.384 Mbits/s Operation
Local stream 16.384 Mbits/s operation is implemented as two multiplexed 8.192 Mbits/s streams. Bits are shifted at
16.384 MHz, and 16 bits are shifted per 8.192 Mbits/s time-slot (refer to Figure 29). This operation makes use of
adjacent pairs of the existing single-byte hold and shift registers for local stream operation, with the local even
stream assigned as the incoming stream, and the local odd stream assigned as the outgoing stream. Pairs are
assigned as LD[0,1], LD[2,3], . . . LD[30,31]. When an L-bus group is set to operate at rate of 16.384 Mbits/s, the
hold and shift circuitry is configured such that the serial output of the even stream shift register feeds the serial
input of the odd stream shift register (refer to Figure 30).
5-9411 (F)
Figure 29. Local Stream 16.384 Mbits/s Timing
5-9426 (F)
Figure 30. Local Stream 16.384 Mbits/s Circuit
15
6
976 ns (ONE 8 Mbits/s TIME-SLOT)
TIME-SLOT n
INCOMING BITS ARE SAMPLED AT
THE 3/4 POINT OF THE BIT TIME
14
13
12
11
10
9
8
7
5
4
3
2
1
0
8.192 MHz
16.384 MHz
SERIAL DATA:
L_D[EVEN] (INCOMING),
L_D[ODD] (OUTGOING)
OFFLOAD INCOMING
BYTES FROM TIME-SLOT n – 1 TO HOLDING REGISTERS,
LOAD OUTGOING BYTES FOR
TIME-SLOT n TO SHIFT REGISTERS
OFFLOAD INCOMING
BYTES FROM TIME-SLOT n TO HOLDING REGISTERS,
LOAD OUTGOING BYTES FOR
TIME-SLOT n + 1 TO SHIFT REGISTERS
LOCAL
EVEN
STREAM
SHIFT
REGISTER
EVEN
STREAM
INCOMING
HOLDING
REGISTER
EVEN
STREAM
OUTGOING
HOLDING
REGISTER
ODD
STREAM
INCOMING
HOLDING
REGISTER
ODD
STREAM
OUTGOING
HOLDING
REGISTER
MS bit
LOCAL
ODD
STREAM
SHIFT
REGISTER
MS bit
8
8-bit BYTE TO
DATA MEMORY
DATA MEMORY
8
8
8-bit BYTE TO
DATA MEMORY
8-bit BYTE FROM
DATA MEMORY
8
(NO LOCAL EVEN
SERIAL OUTPUT
IF 16.384 Mbits/s
OPERATION)
OUTGOING
SERIAL DATA
(EVEN)
OUTGOING SERIAL DATA (ODD)
INCOMING SERIAL DATA (EVEN)
(NO LOCAL ODD
SERIAL INPUT
IF 16.384 Mbits/s
OPERATION)
INCOMING
SERIAL DATA
(ODD)
16.384 Mbits/s
ENABLE