R0K572011S000BE Renesas Electronics America, R0K572011S000BE Datasheet - Page 278

• Manufacturer Part Number: R0K572011S000BE
• Description: KIT STARTER FOR SH7201
• Manufacturer: Renesas Electronics America
• Series: Renesas Starter Kits (RSK)r
• Type: MCUr

Specifications of R0K572011S000BE

• Contents: CPU Board, LCD Display Module, E8 Emulator, Cable, QuickStart Guide and CD-ROM
• For Use With/related Products: SH7201
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Section 9 Bus State Controller (BSC)
(5)
An auto-refresh cycle starts when the auto-refresh operation enable bit (DRFEN) in SDRAM
refresh control register 1 (SDRFCNT1) is set to 1. After that refresh requests are issued at fixed
intervals, activating auto-refresh cycles. However, the activation of auto-refresh cycles may
sometimes be delayed because refresh requests are not accepted during read or write accesses.
A refresh request is issued immediately if the auto-refresh operation enable bit (DRFEN) in
SDRAM refresh control register 1 (SDRFCNT1) is set to 1 while auto-refresh is enabled.
The refresh counter is halted in self-refresh or deep-power-down mode. After recovery from self-
refresh or deep-power-down mode an auto-refresh cycle is activated, after which the counter value
is reset and the counter begins operating again
Make auto-refresh settings in SDRAM refresh control register 1 (SDRFCNT1). Note that refresh
cycles affect all SDRAM channels. Figure 9.9 shows an auto-refresh cycle timing example.
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Auto-Refresh
CKIO
SDRAM command
Figure 9.9 Auto-Refresh Cycle Timing Example (DREFW Bit Set Value: 0010)
Figure 9.8 Example of Timing of Recovery from Self-Refresh Mode
DSL: Deselect command
RFA: Auto-refresh command
RFX: Self-refresh exit command
Self-refresh mode
CKIO
SDRAM command
(CKE = L)
(DREFW Bit Set Value: 0010)
DSL: Deselect command
RFA: Auto-refresh command
Self-refresh clearing
REX
Auto-refresh cycle
RFA
interval
DREFW
DSL
DREFW
DSL
DSL
DSL
RFA
Auto-refresh
cycle
DREFW
DSL
R01UH0026EJ0300 Rev. 3.00
DSL
SH7201 Group
Sep 24, 2010