
iiBusModuLes:sdRaMContRoLLeR(sdRaMC)
s1C33L17teChniCaLManuaL
ePson
ii-4-17
II
SDRAMC
Power-downmode
The S1C33L17 supports two power-down modes for the C33 PE Core (HALT and SLEEP).
haLtmode
The LCDC will be able to access the SDRAM in HALT mode, if it is not disabled in normal mode.
Setting SDAPCPU_CKE (D6/0x301B00) and SDAPCPU_HCKE (D7/0x301B00) determines whether
the CPU and DMA will be able to access the SDRAM in HALT mode or not.
sdaPCPu_CKe:SDRAMCCPUAPPClockControlBitintheGatedClockControlRegister0
(D6/0x301B00)
sdaPCPu_hCKe:SDRAMCCPUAPPClockControl(HALT)BitintheGatedClockControlRegister0
(D7/0x301B00)
TableII.4.1.5.4SDAPP_CPU_CLKClockStatus
Mode
Normalmode
HALTmode
sdaPCPu_hCKe
x
1
0
sdaPCPu_CKe
1
0
1
0
x
sdaPLCdC_CKe
1
0
1
0
1
0
1
0
x
sdRaMclock(
)
On(CPU,DMAandLCDC)
On(CPUandDMA)
On(LCDC)
Off(cannotbeaccessed)
On(DMAandLCDC)
On(DMA)
On(LCDC)
Off(cannotbeaccessed)
:()indicatesthemodulesthatcanaccesstheSDRAM.
note: To maintain data in the SDRAM during HALT status with no SDRAM clock supplied, place the
SDRAMinself-refreshmodebysettingSELDO(D25/0x301608)to1beforestoppingtheSDRAM
clock.
sLeePmode
In SLEEP mode, the SDRAM can be turned off to reduce power consumption by the following procedure:
1. If the CPU runs with the program stored in the SDRAM, it must be changed to a program located in the
built-in RAM or a memory other than the SDRAM.
2. Turn the SDRAM power off.
3. Switch the ports used for the SDRAM to general-purpose ports.
4. Drive the data and address buses to low.
5. Set SDON (D4/0x301600) to 0 to disable the SDRAMC.
6. Execute the slp instruction.
sdon:SDRAMControllerEnableBitintheSDRAMInitialRegister(D4/0x301600)
Perform the following procedure when the CPU wakes up:
1. The CPU wakes up from SLEEP status.
2. Configure the port functions for SDRAM.
3. Release the data and address buses from forced low driving.
4. Turn the SDRAM power on.
5. Wait 100 or 200 s for the SDRAM be stabilize according to the SDRAM specification.
6. Set SDON (D4/0x301600) to 1 to enable the SDRAMC.
7. Initialize the SDRAMC.