TXC-04252AIPQ Transwitch Corporation, TXC-04252AIPQ Datasheet - Page 47

• Manufacturer Part Number: TXC-04252AIPQ
• Manufacturer: Transwitch Corporation

Specifications of TXC-04252AIPQ

• Pin Count: 160
• Screening Level: Industrial
• Package Type: PQFP
• Lead Free Status / Rohs Status: Not Compliant

BUS TIMING
Timing for adding a TU/VT to the add bus is derived from the like-named drop bus, or from the like-named add
bus. Bus timing may be selected by using a lead, or through software. Upon power-up or a device reset, the
SBTEN (Software Bus Timing Enable) control bit is reset to 0 and the ABUST lead controls bus timing selec-
tion. To enable the software to control timing, the SBTEN control bit must be first written with a 1, which will
override the state placed on the ABUST lead. When SBTEN is 1, bus timing (add or drop bus timing) is con-
trolled by the DRPBT control bit. The various states associated with the bus timing selection are shown in the
table below.
UNEQUIPPED OPERATION
The QE1M is capable of sending an unequipped channel or unequipped supervisory channel in all add modes
of operation. Generally a channel which has either the UCHnE bit or both the UCHnE and USCHnE bits set in
the port provisioning registers will add an unequipped channel or unequipped supervisory channel for the
TU/VT selected. An unequipped channel has a TU/VT pointer consisting of a valid NDF, size bits equal to 01,
and a fixed pointer value of 105. The remaining VT overhead bytes and the payload are sent as zeros. The
unequipped supervisory channel has an identical pointer to the unequipped channel, but sends a valid J2 byte,
and valid BIP-2 bits and RDI-bit in V5, and valid RDI-bits in Z7. The QE1M also sends a valid Z6 byte. The V5,
RDI, Z7 RDI, and Z6 bytes can be set to zero by other control bits if they are not required. There are some dif-
ferences in operation based on the UEAME bit in register 014H. The following table describes these differ-
ences.
Note: X = Don’t Care
ABUST lead
High
Low
X
X
Proprietary TranSwitch Corporation Information for use Solely by its Customers.
SBTEN
0
0
1
1
DRPBT
X
X
0
1
Bus Timing Selection
DATA SHEET
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Add bus timing selected by ABUST lead.
Drop bus timing selected by ABUST lead.
Add bus timing selected by DRPBT bit.
Drop bus timing selected by DRPBT bit.
Action
Ed. 3, December 2000
TXC-04252
TXC-04252-MB
QE1M