TXC-05802AIPQ Transwitch Corporation, TXC-05802AIPQ Datasheet - Page 8

• Manufacturer Part Number: TXC-05802AIPQ
• Manufacturer: Transwitch Corporation

Specifications of TXC-05802AIPQ

• Operating Supply Voltage (typ): 3.3/5V
• Operating Temperature Classification: Industrial
• Package Type: PQFP
• Mounting: Surface Mount
• Pin Count: 208
• Lead Free Status / Rohs Status: Not Compliant

To detect CellBus bus errors, a BIP-8 (Bit Interleave Parity byte) is calculated over the 54-byte data field that
extends from the first Tandem Routing Header byte through the final payload data byte, Byte 47. The BIP-8 is
generated by the transmitting CUBIT- Pro using the following algorithm. The first byte of the Tandem Routing
Header is exclusive-or gated with an all-ones byte, creating a starting seed value. This seed value is then
exclusive-or gated with the second byte of the Tandem Routing Header. The result is then exclusive-or gated
with the next byte in the cell. This process is repeated with every successive byte in the cell, through Byte 47 of
the payload, and the final result is transmitted as the BIP-8 byte in cycle 15. The receiving CUBIT- Pro performs
the same process and compares the generated BIP-8 with the received BIP-8. If no errors are detected the
receiving CUBIT- Pro pulls CBACK low, acknowledging receipt of a cell. The CellBus Routing Header has its
own CRC-4 field and is not included in the BIP-8 calculation. A cell with a BIP-8 or CRC-4 error is discarded.
The only signals required to operate the bus which are not sourced by a CUBIT- Pro device are two transfer
clocks: write clock (CBWC) and read clock (CBRC). These clock signals are of the same frequency, but may
be slightly phase-offset to allow for reliable bus operation. The framing pulse used to define the bus frame
cycle is sent out by one of the CUBIT-Pros, and the arbitration function is also performed by the same
CUBIT- Pro . Each CUBIT- Pro contains the circuitry for both the Bus Arbiter and the Frame Pulse Generator.
Only one CUBIT- Pro will have this circuitry enabled, by setting control pin ENARB.
CellBus Bus Cell Routing
The CellBus bus architecture allows several types of cell routing from any one inlet port to the outlet ports of the
CUBIT-Pros on the CellBus bus:
• Point-to-Point Routing: In Unicast or Single Address cell routing a cell coming into an inlet port is transferred
• Point-to-Multipoint (Broadcast): A cell coming into the inlet port can be routed to the outlet ports of all the
• Point-to-Multipoint (Multicast): In multicast routing the cell arriving at the inlet port is sent to the subset of out-
to a single outlet port. The CUBIT- Pro can address a cell to itself, effectively implementing both the inlet and
outlet ports.
CUBIT-Pros on the CellBus bus.
let ports that belong to the specific multicast session by means of selection in the receiving CUBIT-Pros.
Framing Pulse
Cell body
Cell body
Request
Request
Request
Grant
Grant
Figure 4. CellBus Bus 16/32-User Modes - Frame Formats
16-User Mode
Users 1-16
Users 1-16
Users 1-16
- 8 -
Framing Pulse
Cell body
Cell body
Request
Request
Request Users 1-16
Grant
Grant
32-User Mode
Users 17-32
Users 1-16
Ed. 3, November 1999
TXC-05802
CUBIT- Pro
TXC-05802-MB
Even
Odd