XRT94L33IB-L Exar Corporation, XRT94L33IB-L Datasheet - Page 194

• Manufacturer Part Number: XRT94L33IB-L
• Description: IC MAPPER DS3/E3/STS-1 504TBGA
• Manufacturer: Exar Corporation

Specifications of XRT94L33IB-L

• Applications: Network Switches
• Interface: Bus
• Voltage - Supply: 3.14 V ~ 3.47 V
• Package / Case: 504-LBGA
• Mounting Type: Surface Mount
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

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XRT94L33
3-CHANNEL DS3/E3/STS-1 TO STS-3/STM-1 MAPPER IC DATA SHEET
Rev.1.2.0.
The Format of the ATM Cell that is Read from the “Transmit Cell Extraction” Buffer
As the user reads out the contents of an ATM cell from the “Transmit Cell Extraction” Buffer (via the
Microprocessor Interface), they will be expected to read this ATM cell data via a 32-bit wide register/buffer
interface. As a consequence, the user must read out 56 byte size ATM cells from the “Transmit Cell
Extraction” Buffer. The byte format of this 56-byte ATM cell is as illustrated below.
Figure 27: Byte Format of the ATM Cells that are read out from the “Transmit Cell Extraction” Memory
Header Bytes (4 Bytes)
HEC Byte (1 Byte)
User Defined Field (3 Bytes)
Cell Payload Bytes (48 Bytes)
As a consequence, the user must read out a total of 14 “32-bit” words from the “Transmit Cell Extraction”
buffer for each ATM cell that is read out of the Transmit Cell Extraction Buffer.
Procedure for Reading a Cell from the “Transmit Cell Extraction Buffer”
The user can read an ATM cell from the “Transmit Cell Extraction Buffer” within the Transmit ATM Cell
Processor block, by executing the following steps.
STEP 1 – Flush the contents of the “Transmit Cell Extraction Buffer”
This is accomplished by executing a “Transmit Cell Extraction Buffer” RESET. The user can perform this
“Cell Extraction Buffer” RESET by doing the following.
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