DS471 Datasheet, PDF (13/37 Pages) Xilinx, Inc – Channel FIFO

Channel FIFO (CFIFO) (v1.00a)
Figure Top x-ref 9
Clk
Rst
Bus2RFIFO_Ch_Num[0:7]
Bus2RFIFO_Status_RdReq
Bus2RFIFO_Burst
Bus2RFIFO_Data_RdReq
RFIFO2Bus_Ack
RFIFO2Bus_ErrAck
RFIFO2Bus_Ch_Valid
RFIFO2Bus_DBus[0:31]
Comm2RFIFO_Ch_Num[0:7]
RFIFO2Comm_Ch_Valid
Comm2RFIFO_Burst
Comm2RFIFO_WrReq
RFIFO2Comm_Ack
RFIFO2Comm_ErrAck
Comm2RFIFO_DBus[0:31]
RFIFO2Comm_HalfFull
RFIFO2Comm_AlmostFull
RFIFO2Comm_Full
RFIFO2Comm_Vacancy[0:7]
Cycle 1
01
E0000000
6000
0001
01
89AB
CDEF
1122
3344
5566
7788
9900
0000
FF
FE
FD
FC
2
3
4
5
6
2000
0004
FB
7
8
9
10
DS471_09_101405
Figure 9: RFIFO Fixed Length Burst WriteTiming With ACK Delay
RFIFO Write Interface Operational Description
Data received from the data stream is transferred from the communications interface logic to the local
bus interface logic via the Read Channel FIFO (RFIFO). The input (write port) of the RFIFO is
connected to the data stream communications side of the IP (Comm Interface).
During a data receive operation, the Comm Interface specifies a channel number (Comm2RFIFO_) to
the RFIFO and determines that the channel is valid (RFIFO2Comm_ is asserted). The Comm interface
ensures there is room left in the RFIFO (RFIFO2Comm_ is not asserted) and then loads data into the
write port of the RFIFO. The write to the RFIFO is initiated by asserting the Comm2RFIFO_ signal. If
C_COMM_BURST_SIZE is greater than one, then as long as the write request signal is asserted (and the
currently active channel in the RFIFO is not full, and the number of words transferred is less than
C_COMM_BURST_SIZE), the Comm Interface can load data words into the CFIFO at each rising edge of the
clock signal. If the channel becomes full during a burst transfer, the RFIFO will not accept any new write
requests and will indicate this by asserting RFIFO2Comm_ while the write request is asserted. Once
C_COMM_BURST_SIZE words have been written to the RFIFO it will stop responding to the write
request until Comm2RFIFO_ is deasserted.
DS471 April 24, 2009
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13
Product Specification