Renesas H8S/2111B, Hardware Manual

Page: 511 / 582

Rev. 1.00, 05/04, page 477 of 544
20.10 Module Stop Mode
Module stop mode can be individually set for each on-chip peripheral module.
When the corresponding MSTP bit in MSTPCR is set to 1, module operation stops at the end of
the bus cycle and a transition is made to module stop mode. In turn, when the corresponding
MSTP bit is cleared to 0, module stop mode is cancelled and the module operation resumes at the
end of the bus cycle. In module stop mode, the internal states of modules other than the SCI and
PWM are retained.
After the reset state is cancelled, all modules are in module stop mode.
While an on-chip peripheral module is in module stop mode, read/write access to its registers is
disabled.
20.11 Direct Transitions
The CPU executes programs in three modes: high-speed, medium-speed, and subactive. When a
direct transition is made from high-speed mode to subactive mode, there is no interruption of
program execution. A direct transition is enabled by setting the DTON bit in LPWRCR to 1 and
then executing the SLEEP instruction. After a transition, direct transition exception handling
starts.
The CPU makes a transition to subactive mode when the SLEEP instruction is executed in high-
speed mode with the SSBY bit in SBYCR set to 1, the LSON bit and DTON bit in LPWRCR set
to 11, and the PSS bit in TSCR (WDT_1) set to 1.
To make a direct transition to high-speed mode after the time set in the STS2 to STS0 bits in
SBYCR has elapsed, execute the SLEEP instruction in subactive mode with the SSBY bit in
SBYCR set to 1, the LSON bit and DTON bit in LPWRCR set to 01, and the PSS bit in TSCR
(WDT_1) set to 1.