9.6.2.2
MEMSTMG0R - SDRAM timing register 0
This register defines various timing parameters of the SDRAM interface.
All values are given in system clock periods 1/f
HCLK
.
Access
This register can be read/written in 32-bit units.
Address
<MemC_Base> + 04
H
Initial Value
0199 8452
H
. This register is initialized by any reset.
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
TEXSR[4:0]
0
TRC[3:0]
TXSR[3:0]
TRCAR[3:2]
R/W
R/W
R/W
R/W
R/W
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
TRCAR[1:0]
TWR[1:0]
TRP[2:0]
TRCD[2:0]
TRASMIN[3:0]
CASLAT[1:0]
R/W
R/W
R/W
R/W
R/W
R/W
Caution
The default value "0" of bit 26 must not be changed.
Bit
Bit name
Function
31 to 27
21 to 18
TEXSR[4:0]
TXSR[3:0]
TEXSR[4:0] and TXSR[3:0] define the time between exit of SDRAM self-refresh mode by
setting MEMCTRL.SREF = 0 and the start of the auto-refresh mode respectively data
transfer command.
The number of system clocks is calculated by TEXSR[4:0] << 4 + TXSR[3:0]
000
H
1 clock
001
H
2 clocks
...
...
006
H
7 clocks (default)
...
...
1FF
H
512 clocks
25 to 22
TRC[3:0]
TRC[3:0] defines the active-to-active command period.
0
H
1 clock
1
H
2 clocks
...
...
6
H
7 clocks (default)
...
...
F
H
16 clocks
17 to 14
TRCAR[3:0]
TRCAR[3:0] defines the minimum time to wait after auto-refresh before a next auto-
refresh or any other command is performed.
0
H
1 clock
1
H
2 clocks
...
...
6
H
7 clocks (default)
External Memory Interface Controller
Chapter 9
Preliminary User's Manual S19203EE1V3UM00
317
Summary of Contents for uPD72257
Page 39: ...Pin Functions Chapter 2 Preliminary User s Manual S19203EE1V3UM00 39...
Page 44: ...Chapter 2 Pin Functions 44 Preliminary User s Manual S19203EE1V3UM00...
Page 46: ...Chapter 2 Pin Functions 46 Preliminary User s Manual S19203EE1V3UM00...
Page 49: ...Pin Functions Chapter 2 Preliminary User s Manual S19203EE1V3UM00 49...
Page 52: ...Chapter 2 Pin Functions 52 Preliminary User s Manual S19203EE1V3UM00...
Page 54: ...Chapter 2 Pin Functions 54 Preliminary User s Manual S19203EE1V3UM00...
Page 331: ...External Memory Interface Controller Chapter 9 Preliminary User s Manual S19203EE1V3UM00 331...
Page 343: ......