9 SRAM CONTROLLER (SRAMC)
9-4
Seiko Epson Corporation
S1C33L26 TECHNICAL MANUAL
#CE hold time
The hold time for #CE
x
signals (from a read/write signal rising edge to the #CE
x
rising edge) can be set to with-
in the range from 1 to 4 cycles. Use CE
x
HOLD[1:0] in the SRAMC_TMG47 and SRAMC_TMG810 registers
for settings.
4.2.3 #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)
Static wait cycles
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. According to the specifications of the connected
device, set an appropriate wait cycle using CE
x
WAIT[3:0] in the SRAMC_TMG47 and SRAMC_TMG810 reg-
isters. 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.
4.2.4 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
4.2.1 Example of Timing Parameter Settings
Figure 9.