Altera First-In-First-Out Partitioner Bedienungsanleitung PDF herunterladen (Seite 17)

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Getting Started FIFO Partitioner Megafunction User Guide

Figure 9. Writing 16-bit words and reading 8-bit words

FIFOs with a narrow write port and a wide read port

Figure 10 illustrates write and read operations to a FIFO with a 8-bit-wide

write-side bus, and a 16-bit-wide read-side bus. In this example the read

port is operating at half the frequency of the write port. Four 8-bit words

are written to the FIFO. Notice that the wr_level_3 flag is incremented

to 4, and the rd_level_3 flag is incremented to 2. Two 16-bit word read

operations empty the FIFO. Notice that the first 8-bits written to the FIFO

are the least-significant 8 bits in the 16-bit read operation. Also note that

rd_empty_n does not deassert, indicating that data is available, until

enough words have been written on the narrow write port, to fill an entire

word on the wide read-side port.

clk_port_a_2

wr_en_a_2

wr_data_a_2

wr_level_2

wr_empty_2

wr_full_2

clk_port_b_2

read_b_2

rd_data_b_2

rd_level_2

rd_full_2

rd_empty_2

0 2 4 321 0

000201 FF

FF01 0002 0003 0004 0005 00070006 0008

1 2 ... 12 13 14 15 16 17 18 19 20 21 22

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Altera First-In-First-Out Partitioner Bedienungsanleitung Seite 17