PM7344 S/UNI-MPH
DATA SHEET
PMC-950449
ISSUE 6
MULTI-PHY USER NETWORK INTERFACE
After an abort, the RFDL state machine will be in the receiving all ones state, and
the data link status will be idle. When the first flag is detected, a new interrupt
will be generated, with a dummy data byte loaded into the FIFO buffer, to
indicate that the data link is now active.
Figure 28
- RFDL FIFO Overrun
B1 B2 B3
Serial Data
extracted from
ESF FDL
Flag D1 D2 D3
Dn-1 Dn R C1 C2 Flag D1 R Abort
RDLINT[x]
RDLEOM[x]
D[7:0]
D1D2
STATUSRD
OVR
This diagram shows the relationship between RFDL inputs and outputs for the
case where interrupts are programmed to occur when two data bytes are present
in the FIFO buffer. Each read is composed of two register reads, as described
above. In this example, data is not read by the end of B2. An overrun occurs
since unread data (Dn-3) has been overwritten by B1. This sets the RDLEOM[x]
output high, and resets both the RFDL and the FIFO buffer. The RFDL is held
disabled until the Status Register is read. The start flag sequence is not
detected since the RFDL is still held disabled when it occurs. Consequently, the
RFDL will ignore the entire frame including the abort sequence (since it has not
occurred in a valid frame or during flag reception, according to the RFDL).
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
237
PMC [ PMC-SIERRA, INC ]
