Section 8 Bus State Controller (BSC)
Rev. 5.00 May 29, 2006 page 230 of 698
REJ09B0146-0500
Tp
TRr
TRrw
TRrw
(Tpc)
CKIO
CKE
CSn
RASU
,
RASL
CASU
,
CASL
RD/
WR
Figure 8.25 Synchronous DRAM Auto-Refresh Timing
2. Self-Refreshing
Self-refresh mode is a kind of standby mode in which the refresh timing and refresh addresses
are generated within the synchronous DRAM. Self-refreshing is activated by setting both the
RMODE bit and the RFSH bit to 1. The self-refresh state is maintained while the CKE signal
is low. Synchronous DRAM cannot be accessed while in the self-refresh state. Self-refresh
mode is cleared by clearing the RMODE bit to 0. After self-refresh mode has been cleared,
command issuance is disabled for the number of cycles specified by the TPC bits in MCR.
Self-refresh timing is shown in figure 8.26. Settings must be made so that self-refresh clearing
and data retention are performed correctly, and auto-refreshing is performed at the correct
intervals. When self-refreshing is activated from the state in which auto-refreshing is set, or
when exiting standby mode other than through a power-on reset, auto-refreshing is restarted if
RFSH is set to 1 and RMODE is cleared to 0 when self-refresh mode is cleared. If the
transition from clearing of self-refresh mode to the start of auto-refreshing takes time, this time
should be taken into consideration when setting the initial value of RTCNT. Making the
RTCNT value 1 less than the RTCOR value will enable refreshing to be started immediately.
After self-refreshing has been set, the self-refresh state continues even if the chip standby state
is entered using the this LSI standby function, and is maintained even after recovery from
standby mode other than through a power-on reset. In case of a power-on reset, the bus state
controller's registers are initialized, and therefore the self-refresh state is cleared.
Self-refreshing is performed in normal operation, in sleep mode, in standby mode, and in case
of a manual reset.
Summary of Contents for SH7706 Series
Page 8: ...Rev 5 00 May 29 2006 page viii of xlviii ...
Page 160: ...Section 5 Cache Rev 5 00 May 29 2006 page 112 of 698 REJ09B0146 0500 ...
Page 370: ...Section 11 Watchdog Timer WDT Rev 5 00 May 29 2006 page 322 of 698 REJ09B0146 0500 ...
Page 554: ...Section 17 Pin Function Controller PFC Rev 5 00 May 29 2006 page 506 of 698 REJ09B0146 0500 ...
Page 576: ...Section 18 I O Ports Rev 5 00 May 29 2006 page 528 of 698 REJ09B0146 0500 ...
Page 746: ...Index Rev 5 00 May 29 2006 page 698 of 698 REJ09B0146 0500 ...
Page 749: ...SH7706 Group Hardware Manual ...