peb3456 Infineon Technologies Corporation, peb3456 Datasheet - Page 72

• Manufacturer Part Number: peb3456
• Description: Channelized T3 Termination With Ds3 Framer, M13 Multiplexer, T1/ E1 Framers And 256 Channel Hdlc/ppp Controller
• Manufacturer: Infineon Technologies Corporation

4.4.1
The internal receive buffer provides buffering of frame data and status between the
protocol handler and the receive data management units. Internal buffers are essential
to avoid data loss due to the PCI bus latency, especially in the presence of multiple
devices on the same PCI bus, and to enable a minimized bus utilization through burst
accesses.
The incoming data from the protocol handler is stored in a receive central buffer shared
complete DWORD is ready or the last byte of a frame has been received. Each channel
has an individual programmable threshold code, which determines after how many
DWORDs a data transfer into the shared memory is generated. The threshold therefore
defines the maximum burst length for a particular channel in receive direction. A data
transfer is also requested as soon as a frame end has been reached. Programming the
burst length to be greater than 1 DWORD avoids too frequent accesses to the PCI bus,
thereby optimizing use of this resource.
For real time channels with lowest possible latency (example: constant bit rate) a value
Table 4-3
Table 4-4
4.3.7
Data is transmitted beginning with byte zero in increasing order. Vice versa data
received is stored starting with byte zero. The position of byte zero depends on the
selected endian mode.
Each byte itself consists of eight bits starting with bit zero (LSB) up to bit seven (MSB).
Data on the serial line is transmitted starting with the LSB. The first bit received is stored
in bit zero.
4.4
by all the 256 channels. The buffer is written by the protocol handler every time a
of one DWORD can be selected for the burst length.
Data Sheet
BNO
BNO
3
7
Transmission Bit/Byte Ordering
Buffer Management
Internal Receive Buffer
Byte3
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-
Example for little/big Endian with BNO = 3
Example for little big Endian with BNO = 7
Byte 2
Byte 2
Byte 6
Little Endian
Little Endian
Byte 1
Byte 1
Byte 5
Byte 0
Byte 0
Byte 4
72
Byte 0
Byte 0
Byte 4
Byte 1
Byte 1
Byte 5
Big Endian
Big Endian
Functional Description
Byte 2
Byte 2
Byte 6
PEB 3456 E
Byte3
05.2001
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