h8s-2138 Renesas Electronics Corporation., h8s-2138 Datasheet - Page 756

• Manufacturer Part Number: h8s-2138
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family/h8s/2100 Series
• Manufacturer: Renesas Electronics Corporation.

Section 24 Power-Down State
24.11
24.11.1 Overview of Direct Transition
There are three operating modes in which the CPU executes programs: high-speed mode, medium-
speed mode, and subactive mode. A transition between high-speed mode and subactive mode
without halting the program is called a direct transition. A direct transition can be carried out by
setting the DTON bit in LPWRCR to 1 and executing a SLEEP instruction. After the transition,
direct transition exception handling is started.
Direct Transition from High-Speed Mode to Subactive Mode: If a SLEEP instruction is
executed in high-speed mode while the SSBY bit in SBYCR, the LSON bit and DTON bit in
LPWRCR, and the PSS bit in TSCR (WDT1) are all set to 1, a transition is made to subactive
mode.
Direct Transition from Subactive Mode to High-Speed Mode: If a SLEEP instruction is
executed in subactive mode while the SSBY bit in SBYCR is set to 1, the LSON bit is cleared to 0
and the DTON bit is set to 1 in LPWRCR, and the PSS bit in TSCR (WDT1) is set to 1, after the
elapse of the time set in bits STS2 to STS0 in SBYCR, a transition is made to directly to high-
speed mode.
24.12
1. When making a transition to subactive mode or watch mode, set the DTC to enter module stop
2. The on-chip peripheral modules (DTC and TPU) which halt operation in subactive mode
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REJ09B0301-0400
mode (write 1 to the relevant bits in MSTPCR), and then read the relevant bits to confirm that
they are set to 1 before mode transition. Do not clear module stop mode (write 0 to the relevant
bits in MSTPCR) until a transition from subactive mode to high-speed mode or medium-speed
mode has been performed.
If a DTC activation source occurs in sub-active mode, the DTC will be activated only after
module stop mode has been cleared and high-speed mode or medium-speed mode has been
entered.
cannot clear an interrupt in subactive mode. Therefore, if a transition is made to sub-active
mode while an interrupt is requested, the CPU interrupt source cannot be cleared. Disable the
interrupts of each on-chip peripheral module before executing a SLEEP instruction to enter
subactive mode or watch mode.
Direct Transition
Usage Notes