9 SRAM CONTROLLER (SRAMC)
9-12
Seiko Epson Corporation
S1C33L26 TECHNICAL MANUAL
D[29:28], D[21:20], D[13:12], D[5:4]
CE
x
HOLD[1:0]: #CE
x
Hold Cycle Bits
Configures the #CE
x
signal hold time (read/write signal rising edge to #CE
x
rising edge).
7.3 #CE Hold Time Settings
Table 9.
CE
x
HOLD[1:0]
Hold time
0x3
4 cycles
0x2
3 cycles
0x1
2 cycles
0x0
1 cycle
(Default: 0x3)
D[27:24], D[19:16], D[11:8], D[3:0]
CE
x
WAIT[3:0]: #CE
x
Static Wait Cycle Bits
Configures the #CE
x
signal static wait cycle. If the number of static wait cycles is specified, the chip
enable and read/write signals are always prolonged for the number of specified cycles when the area is
accessed. If CE
x
WAIT[3:0] is set to 0, no static wait cycle is inserted. In this case, the minimum read/
write pulse width will be one cycle.
7.4 Static Wait Cycle Settings
Table 9.
CE
x
WAIT[3:0]
Static wait cycle
Read/write cycle
0xf
15 cycles
16 cycles (+ #WAIT)
0xe
14 cycles
15 cycles (+ #WAIT)
:
:
:
0x1
1 cycle
2 cycles (+ #WAIT)
0x0
0 cycles
1 cycle (+ #WAIT)
(Default: 0xf)
The area to which an SRAM device is connected allows dynamic wait control using the #WAIT pin in
addition to the static wait control.
BCLK
A[25:0]
#CE
x
#RD/#WR
*
D[15:0] (RD)
D[15:0] (WR)
#WAIT
valid
valid
(CE
x
SETUP = 0x0)
(CE
x
WAIT = 0x1)
(CE
x
HOLD = 0x0)
External wait cycle
via #WAIT
Static wait cycle
#CE setup cycle
#CE hold cycle
valid
7.1 Example of Timing Parameter Settings
Figure 9.