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RELEASED
DATA SHEET
PM7366 FREEDM-8
ISSUE 4
PMC-1970930
FRAME ENGINE AND DATA LINK MANAGER
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA,INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
40
Field
Description
Offset[1:0]
The Offset[1:0] bits indicate the byte offset of the data packet from the
start of the buffer. If this value is non-zero, there will be ‘dummy’ (i.e.
undefined) bytes at the start of the data buffer prior to the packet data
proper.
For a linked list of RPDs, only the first RPD's Offset field is valid. All
other RPD Offset fields of the linked list are set to 0.
Status [5:0]
The Status[5:0] bits indicate the status of the received packet.
Status[0]
Status[1]
Status[2]
Status[3]
Status[4]
Status[5]
Rx buffer overrun
Packet exceeds max. allowed size
CRC error
Packet Length not an exact no. of bytes
HDLC abort detected
Unused (set to 0)
For a linked list of RPDs, only the last RPD's Status field is valid. All
other RPD Status fields of the linked list are invalid and should be
ignored. When a packet requires only one RPD, the Status field is
valid.
Bytes in Buffer [15:0]
The Bytes in Buffer[15:0] bits indicate the number of bytes actually
used in the current RPD's data buffer to store packet data. The count
excludes the 'dummy' bytes inserted as a result of a non-zero Offset
field. A count greater than 32767 bytes indicates a packet that is
shorter than the expected length of the FCS field.
The Bytes in Buffer field is invalid when Status[0] or Status[4] is
asserted .
Next RPD Pointer
[13:0]
The Next RPD Pointer[13:0] bits store a RPDR which enables the
RMAC to support linked lists of RPDs. This field, which is only valid
when CE is equal to logic zero, contains the RPDR to the next RPD in
a linked list. The RMAC links RPDs when more than one buffer is
needed to store a packet.
The Next RPD Pointer is not valid for the last RPD in a linked list
(when CE=1). When a packet requires only one RPD, the Next RPD
Pointer field is not valid.
Receive Buffer Size
[15:0]
The Receive Buffer Size[15:0] bits indicate the size in bytes of the
current RPD's data buffer. This field is expected to be configured by
the Host during initialisation. The Receive Buffer Size must be a non-
zero integer multiple of 16 and less than or equal to 32752.
The Receive Buffer Size field is valid in all RPDs.