pef20320 Infineon Technologies Corporation, pef20320 Datasheet - Page 196

• Manufacturer Part Number: pef20320
• Description: Multichannel Network Interface Controller For Hdlc With 32 Channels
• Manufacturer: Infineon Technologies Corporation

User’s Manual
The fe-bit marks the end of one HDLC frame, the EOF bit marks the end of the Ethernet
frame. The additional information comprises the 8-bit word descriptor count, 16-bit word
frame count and EOF a 8-bit variable which indicates the last descriptor of the frame.
Message Entry Point
The message entry point calls two functions: IsdnRouteFrame and LanRouteFrame. An
Ethernet frame is processed by IsdnRouteFrame, an ISDN frame by LanRouteFrame.
The MUNICH32 receive descriptors are converted to LAN controller transmit descriptors
and those of the LAN controller are converted to MUNICH32 transmit descriptors.
Figure 94
Message Flow between DDMs and MROUTE Module
Besides the IsdnRouteFrame realizes the insertion of additional information and splits
an Ethernet frame on several B-channels. The additional information is stored in an extra
allocated transmit descriptor which is placed before the descriptor containing the data.
Every descriptor and the respective extra descriptor are connected to one message
descriptor. This message with set hold bit and set fe-bit in the descriptor containing the
data is further processed from the MUNICH32 DDM routine ‘Send Frame’.
LanRouteFrame reassembles the Ethernet frames. It takes into account, that the parts
might arrive with different delays. Every complete frame is connected to a message
descriptor and than processed from the LAN controller DDM.
MUNICH32
RC Descr
Message Descr
MUNICH32
TX Descr
MUNICH32
DDM
ISDN Route Frame
LAN Route Frame
MROUTE Module
196
LAN Controller
DDM
Application Notes
Message Descr
LAN Controller
TX Descr
LAN Controller
RC Descr
PEB 20320
ITS08292
01.2000