Toshiba TMPR4925, Руководство пользователя

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Chapter 9 SDRAM Controller
9-15
9.4.2 SDRAM Timing Register (SDCTR) 0x8020
31 29 28 27 26 25 24 23 22 18 17 16
BC ACP PT RCD ACE PDAE RC CASL DRB
R/W R/W R/W R/W R/W R/W R/W R/W R/W : Type
101 11 1 1 0 0 00000 1 0
: Initial
value
15 14 13 12 11 0
DA SWB DIA RP
R/W R/W R/W R/W : Type
1 1 11 0x270
: Initial
value
Bits Mnemonic Field Name Description
31:29 BC Bank Cycle Time Bank Cycle Time (t
RC
) (Initial value: 101, R/W)
Specifies the bank cycle time.
( * 2)
000: 5 t
CK
(
*
1)
100: 9 t
CK
001: 6 t
CK
101: 10 t
CK
010: 7 t
CK
110: Reserved
011: 8 t
CK
111: Reserved
28:27 ACP Active Command
Time Active Command Period (tRAS) (Initial value: 11, R/W)
Specifies the active command time.
00: 3 t
CK
01: 4 t
CK
10: 5 t
CK
11: 6 t
CK
26 PT Precharge Time Precharge Time (tRP) (Initial value: 1, R/W)
Specifies the precharge time.
0: 2 t
CK
1: 3 t
CK
25 RCD RAS-CAS Delay RAS to CAS Delay (tRCD) (Initial value: 1, R/W)
Specifies the RAS - CAS delay.
0: 2 t
CK
1: 3 t
CK
24 ACE Advanced CKE Advanced CKE enable (Initial value: 0, R/W)
Enabling this function makes the timing at which CKE changes one cycle earlier.
0: Disable
1: Enable
23 PDAE Power Down
Auto Entry
Power Down Auto Entry Enable (Initial value: 0, R/W)
Enabling this function makes CKE become “L” while the SDRAMC is in the Idle
state. When refresh, memory access, or command execution is performed, CKE
automatically becomes “H”, the requested operation is performed, then CKE returns
to “L” when the operation is complete.
0: Disable
1: Enable
Figure 9.4.2 SDRAM Timing Register (1/2)