Achronix Speedster22i User Macro Guide - Manual (Page 139)

Memories BRAM80KFIFO
Speedster22i Macro Cell Library Achronix Semiconductor Proprietary PAGE 122
Table 6-17: FIFO write_width versus Maximum Write Depth
write_width
FIFO Write
Depth
fwft = 1’b0
FIFO Write
Depth
fwft = 1’b1
40 2048 2049
36 2048 2049
32 2048 2049
20 4096 4097
18 4096 4097
16 4096 4097
10 8192 8193
9 8192 8193
8 8192 8193
5 16384 16385
4 16384 16385
2 32768 32769
1 65536 65537
Table 6-18: din, dinp, dinpx bit assignments per write_width values
write_width dinpx[3:0] dinp[3:0] din[31:0]
user_din[39:36] user_din[35:32] user_din[31:0]
4’hx user_din[35:32] user_din[31:0]
4’hx 4’hx user_din[31:0]
2’bxx,user_din[19:18] 2’bxx,user_din[17:16] 16’hxxxx,user_din[15:0]
4’hx user_din[17:16] 16’hxxxx,user_din[15:0]
4’hx 4’hx 16’hxxxx,user_din[15:0]
3’bxxx,user_din[9] 3’bxxx,user_din[8] 24’hxxxxxx,user_din[7:0]
4’hx 3’bxxx,user_din[8] 24’hxxxxxx,user_din[7:0]
4’hx 4’hx 24’hxxxxxx,user_din[7:0]
4’hx 3’bxxx,user_din[4] 28’hxxxxxxx,user_din[3:0]
4’hx 4’hx 28’hxxxxxxx,user_din[3:0]
4’hx 4’hx 30’hxxxxxxxx,user_din[1:0]
4’hx 4’hx 31’hxxxxxxxx,user_din[0]
read_width
The read_width parameter defines the width of the data output bus of the FIFO from one to
forty bits. The allowed value of the read_width is subject to the combinations defined below
in
Table 6‐19: FIFO read_width versus Maximum Read Depth . Table 6‐17: FIFO
write_width versus Maximum Write Depth defines the maximum depth of the FIFO for each
of the valid values of the write_width parameter. The default value of the read_width
parameter is 40’h0.
40
36
32
20
18
16
10
9
8
5
4
2
1