Table of Contents
Advertisement
5.8
Direct Transfer
5.8.1
Overview of Direct Transfer
The CPU can execute programs in three modes: active (high-speed) mode, active (medium-speed)
mode, and subactive mode. A direct transfer is a transition among these three modes without the
stopping of program execution. A direct transfer can be made by executing a SLEEP instruction
while the DTON bit in SYSCR2 is set to 1. After the mode transition, direct transfer interrupt
exception handling starts.
If the direct transfer interrupt is disabled in interrupt enable register 2, a transition is made instead
to sleep mode or watch mode. Note that if a direct transition is attempted while the I bit in CCR is
set to 1, sleep mode or watch mode will be entered, and it will be impossible to clear the resulting
mode by means of an interrupt.
• Direct transfer from active (high-speed) mode to active (medium-speed) mode
When a SLEEP instruction is executed in active (high-speed) mode while the SSBY and LSON
bits in SYSCR1 are cleared to 0, the MSON bit in SYSCR2 is set to 1, and the DTON bit in
SYSCR2 is set to 1, a transition is made to active (medium-speed) mode via sleep mode.
• Direct transfer from active (medium-speed) mode to active (high-speed) mode
When a SLEEP instruction is executed in active (medium-speed) mode while the SSBY and
LSON bits in SYSCR1 are cleared to 0, the MSON bit in SYSCR2 is cleared to 0, and the DTON
bit in SYSCR2 is set to 1, a transition is made to active (high-speed) mode via sleep mode.
• Direct transfer from active (high-speed) mode to subactive mode
When a SLEEP instruction is executed in active (high-speed) mode while the SSBY and LSON
bits in SYSCR1 are set to 1, the DTON bit in SYSCR2 is set to 1, and the TMA3 bit in TMA is set
to 1, a transition is made to subactive mode via watch mode.
• Direct transfer from subactive mode to active (high-speed) mode
When a SLEEP instruction is executed in subactive mode while the SSBY bit in SYSCR1 is set to
1, the LSON bit in SYSCR1 is cleared to 0, the MSON bit in SYSCR2 is cleared to 0, the DTON
bit in SYSCR2 is set to 1, and the TMA3 bit in TMA is set to 1, a transition is made directly to
active (high-speed) mode via watch mode after the waiting time set in SYSCR1 bits STS2 to STS0
has elapsed.
112
Advertisement
Table of Contents
