TSI148-133CL IDT, Integrated Device Technology Inc, TSI148-133CL Datasheet - Page 48

• Manufacturer Part Number: TSI148-133CL
• Description: IC PCI-VME BRIDGE 456PBGA
• Manufacturer: IDT, Integrated Device Technology Inc
• Series: Tsi148&Trade;r

Specifications of TSI148-133CL

• Applications: PCI-to-VME Bridge
• Interface: PCI
• Voltage - Supply: 3.3V
• Package / Case: 456-PBGA
• Mounting Type: Surface Mount
• Package Type: BGA
• Rad Hardened: No
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 800-1906

2. VME Interface > VME Slave
2.2.1.2
48
VME Slave Transactions
The Tsi148 VMEbus Interface supports different transaction types, including one to four byte
single beat transactions, and burst transactions. These transactions must be mapped to
corresponding transactions on the destination bus. For more information on transaction
mapping, refer to
VME Slave Read Transaction
VME Slave read operation depends on whether the transfer is a block or single cycle. If the
transfer is a SCT, the VME Slave requests a single beat transfer from the Linkage Module.
The VMEbus acknowledgement is held until the data is received from PCI/X.
If the read operation is a block transfer, the VME Slave requests a block of data from the
Linkage Module. The VME Slave read buffer is used to store the data received from the
Linkage Module. The data is stored in the buffer until it is needed to complete a VMEbus
transaction.
The VME Slave read buffer has a programmable virtual buffer size and refill threshold. This
flexibility enables the buffer to be optimized for various block sizes. The virtual buffer size
can be set to 64, 128, 256 or 512 bytes. The virtual buffer size and refill threshold are
programmable in the Slave Image registers (see
When the VME Slave receives a BLT or MBLT read command, the VME Slave prefetches
data (through the Linkage Module to get the data) based on the virtual buffer size.
As data is removed from the VME Slave read buffer, it is refilled based on the refill threshold.
The refill threshold can be set to half-full or empty. When the refill threshold is set to half-full,
the VME Slave read buffer is refilled when it is less than half-full. This functionality enables
the VMEbus master to read data from PCI/X without interruption. In applications where the
packet size is small, the data from the initial read can be all that is required and reading
additional data would waste PCI/X bus bandwidth. In this case, the refill threshold can be set
to empty to conserve bandwidth on the PCI/X bus. If the buffer is drained and additional data
is required by the VME Master, the buffer is refilled based on the buffer size and address.
When the VME Slave receives a 2eVME or 2eSST read command, the prefetch size is
determined by the byte count received from the VMEbus master. The entire byte count is read
on the PCI/X bus. Tsi148 supports the maximum 2eVME/2eSST byte-count of 2 Kbytes.
Prefetching is not used during Single Cycle Transfers.
Section 2.2.1.1 on page
45.
Section 10.4.46 on page
Tsi148 PCI/X-to-VME Bus Bridge User Manual
277).
80A3020_MA001_13