Toshiba TLCS-900/H1 Series Manual page 395

6. "Auto Exit" problem when exiting from SDRAM Self-Refresh Mode
The SDRAM specification may not be satisfied when using the Self-Refresh function
together with CPU stand-by function or changing clock,. because when the CPU releases
HALT mode, the Self-Refresh Auto Exit function automatically operates.
The following figure shows an example of how to avoid this problem using S/W.
(Control Outline)
f
SYS
20MHz
｜
｜
32KHz
CPU
SR Change
ENTRY
Port condition
SDRAM control pin
SDRAM controller
internal condition
AR
condition
SDRAM condition
AR
condition
*The target ports to change are SDCKE pin and SDCS pin.
*The method of Self-refresh Entry includes the condition 4).
* SR : Self-refresh , AR : Auto-refresh
Gear-down or
Change to Low clock
Change
HALT
to port CLK
HALT
condition
General port setting
SR condition
Gear-up or
Change to High clock
Interrupt
SR
Change
ENTRY
CLK
AR
condition
Auto EXIT
SR condition
92CH21-393
TMP92CH21
Change
SR
to port
EXIT
SDRAM control pin
SR condition
condition
condition
2009-06-19
AR
AR