Cirrus Logic EP73xx - Manual (Page 88)

8-4 EP7309/11/12 User’s Manual - DS508UM4
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Copyright Cirrus Logic, Inc. 2003
SRAM/Expansion Bus Controller
8
Wait States Field[2:5]: There are two tables to use to program a chip select with
a specific number of wait states. One table is specifically for 13
and 18 MHz operation and the other is for 36 MHz and above. The
operating speed of the bus will determine which table is used.
01 32-bit wide bus access High, Low
10 Reserved High, Low
11 8-bit wide bus access High, Low
Table 8-3: Wait States at 13 / 18 MHz Operation
13 MHz / 18 MHz Operation
Bit 3 Bit 2 Bit 1 Bit 0 Wait States Random Wait States Sequential
x x 0 0 4 3
x x 0 1 3 2
x x 1 0 2 1
x x 1 1 1 0
Table 8-4: Wait States at 36 MHz Operation
36 MHz Operation
Bit 3 Bit 2 Bit 1 Bit 0 Wait States Random Wait States Sequential
0 0 0 0 8 3
0 0 0 1 7 3
0 0 1 0 6 3
0 0 1 1 5 3
0 1 0 0 4 2
0 1 0 1 3 2
0 1 1 0 2 2
0 1 1 1 1 2
1 0 0 0 8 1
1 0 0 1 7 1
1 0 1 0 6 1
1 0 1 1 5 1
1 1 0 0 4 0
1 1 0 1 3 0
1 1 1 0 2 0
1 1 1 1 1 0
Table 8-2: Bus Width Selection Settings
Bus Width Field Expansion Transfer Mode
Port E bits 1,0 during
nPOR reset