
iiBusModuLes:sdRaMContRoLLeR(sdRaMC)
s1C33L17teChniCaLManuaL
ePson
ii-4-23
II
SDRAMC
0x301600:sdRaMinitialRegister(psdRaMC_ini)
name
address
Registername
Bit
Function
setting
init. R/W
Remarks
–
–
sdon
sden
iniMRs
iniPRe
iniReF
D31–5
D4
D3
D2
D1
D0
reserved
SDRAMcontrollerenable
SDRAMinitializeflag
MRScommandenableforinit.
PALLcommandenableforinit.
REFcommandenableforinit.
–
0
–
R/W
R
R/W
0whenbeingread.
00301600
(W)
1 Initialized
0 Notinitialized
1 Enabled
0 Disabled
1 Enabled
0 Disabled
1 Enabled
0 Disabled
1 Enabled
0 Disabled
sdRaMinitial
register
(pSDRAMC_INI)
d[31:5] Reserved
d4
sdon:sdRaMControllerenableBit
This bit enable the SDRAM controller.
1 (R/W): Enable
0 (R/W): Disable (default)
When SDON is set to 1, the SDRAM controller activates. Before setting SDON to 1, the SDRAMC
clocks must be supplied to the SDRAM controller.
d3
sden:sdRaMinitializeFlag
This bit indicates that the SDRAM has finished initialization (Mode Register Set).
1 (R):
Initialized
0 (R):
Not initialized (default)
SDEN is reset to 0 after power-on, and is set to 1 upon completion of the initialization sequence. Make
sure that SDEN is set to 1 before the SDRAM is accessed.
d2
iniMRs:MRsCommandenableforinitializationBit
This bit enables to output the MRS (Mode Register Set) command for initialization sequence.
1 (R/W): Enable
0 (R/W): Disable (default)
In order to initialize the SDRAM, the PALL (Precharge All), REF (Auto Refresh), and MRS (Mode
Register Set) commands must be executed sequentially. Note that the initialization sequence depends on
the SDRAM. Refer to the specifications of the SDRAM to be used for the initialization sequence.
Example 1: PALL
→ REF → REF → MRS (→ EMRS)
Example 2: PALL
→ MRS → REF → REF (→ REF → REF → REF → REF → REF → REF)
To execute the MRS/EMRS (Mode Register Set/Extended Mode Register Set) command, write 0x14
to this register (INIMRS should be set to 1). Then write any data to a specific address shown below
according to the CAS latency (MRS) or extended mode parameters (EMRS).
TableII.4.4.2DataWriteAddresstoExecutetheMRS/EMRSCommand
CPuaddress
sdRaMaddress
MRs
CASlatency=1
CASlatency=2
CASlatency=3
eMRs
A15
A14
A13
A12
A11
A10
A9
A8
A7
A6
A5
A4
A3
A2
A1
1
0
SeeSDRAMspecifications.
0
1
0
1
0
1
0
1
BA1
Mode
reserved
Testmode
CASlatency
WB
Burstlength
BT
Mode
reserved
DS
PASR
TCSR
BA0
SDA12 SDA11 SDA10 SDA9
SDA8
SDA7
SDA6
SDA5
SDA4
SDA3
SDA2
SDA1
SDA0
For example, to execute an MRS command with 2 of CAS latency specified, write data (any value) to
address 0x10000442 (when the SDRAM is mapped to area 19) after writing 0x14 to the SDRAM Initial
Register (0x301600).
note: TheCASlatencyspecifiedintheMRScommandmustbethesameastheCAS[1:0](D[3:2]/
0x301610)setvalue.
Cas[1:0]: CASLatencySetupBitsintheSDRAMApplicationConfigurationRegister(D[3:2]/0x301610)