PM7344 datasheet(250/293 Pages) PMC

250 / 293 page

PM7344 S/UNI-MPH

DATA SHEET

PMC-950449

ISSUE 6

MULTI-PHY USER NETWORK INTERFACE

PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE

234

c) If FLG=1 and the link state was inactive, then set the link state to active,

discard the last data byte, and go to step 1.

ELSE

d) Save the last data byte read.

e) If EOM=1, then read the CRC and NVB[2:0] bits of the RFDL Status

f) If FE=0, then go to step 2, else go to step 1.

DMA-Controlled Mode

The RFDL can also be used with a DMA controller to process the frame data. In

the DMA controlled mode, the RDLINT[x] output of the RFDL is used as a DMA

request input to the DMA controller, and the RDLEOM[x] output is used as an

interrupt to the processor to allow handling of exceptions and as an indication of

when to process a frame. The RXDMASIG bit of the Datalink Options Register

should be set to logic 1.

The RDLINT[x] output of the RFDL is connected through a gate to the DMA

request input of the DMA controller to optionally inhibit the DMA request if the

RDLEOM[x] output is high. The DMA controller reads the data bytes from the

RFDL whenever the RDLINT[x] output is high. When the current byte read from

the RFDL Receive Data Register is the last byte in a frame (due to an end-of-

message or an abort), or an overrun condition occurs, then the RDLEOM[x]

output goes high. The DMA controller is inhibited from reading any more bytes,

and the processor is interrupted. The processor can then halt the DMA

controller, read the RFDL Status Register, process the frame, and finally reset

the DMA controller to process the data for the next frame. The RDLEOM[x]

output can optionally be enabled to generate a processor interrupt through the

common INTB output via the RDLEOME bit in the Datalink Options register,

rather than tying the RDLEOM[x] output directly to the microprocessor. This

allows a central microprocessor controlling the S/UNI-MPH operation to also

respond to conditions affecting the DMA servicing of RFDL. When using the

INTB output, the central processor must poll the Source Selection/Interrupt ID,

Interrupt Source #1 and Interrupt Source #2 Registers to identify the source of

the interrupt before beginning any interrupt service routine.

PM7344 Datasheet(PDF) 250 Page - PMC-Sierra, Inc