PM8313 datasheet(153/192 Pages) PMC

153 / 192 page

PM8313 D3MX

DATA SHEET

PMC-920702

ISSUE 5

M13 MULTIPLEXER

143

link state as idle (all ones or bit-oriented messages active) or active (flags

received).

The RFDL can be used in a polled, interrupt driven, or DMA controlled mode for

the transfer of frame data. In the polled mode, the RDLINT and RDLEOM

outputs of the RFDL are not used, and the processor controlling the RFDL must

periodically read the Status Register to determine when to read the Data

the RDLINT output to determine when to read the Data Register. In the DMA

controlled mode, the RDLINT output of the RFDL is used as a DMA request input

to the DMA controller, and the RDLEOM output is used as an interrupt to the

processor to allow handling of exceptions and as an indication of when to

process a frame.

In the case of interrupt driven data transfer from the RFDL to the processor, the

RDLINT output of the RFDL is connected to the interrupt input of the processor.

The processor interrupt service routine should process the data in the following

order:

1. Read the RFDL Data Register.

2. Read the RFDL Status Register to check for, in order, underrun, OVR, FLG,

EOMR, and FE.

3. If the FIFO has underrun (i.e. the Status Register returns 00 Hex), then

discard the last data byte and wait for the next interrupt.

4. If OVR=1, then discard the last frame and wait for the next interrupt.

5. If FLG=0 (i.e. an abort has been received) and the link state was active, then

set the link state to inactive, discard the last frame, and wait for the next

interrupt.

6. If FLG=1 and the link state was inactive, then set the link state to active,

discard the last data byte, and wait for the next interrupt.

7. Otherwise, save the last data byte read.

8. If EOMR=1, then check the CRC, NVB and process the frame.

9. If FE=0, then go to step 1, else wait for the next interrupt.

The interrupt service routine can optionally read the Status Register first to check

for an overrun condition, and then for available data, before advancing to step

one above.

PM8313 Datasheet(PDF) 153 Page - PMC-Sierra, Inc