HD6433802H Datasheet, PDF (128/435 Pages) Hitachi Semiconductor – Single-Chip Microcomputer

5.7 Active (Medium-Speed) Mode
5.7.1 Transition to Active (Medium-Speed) Mode
If the RES pin is driven low, active (medium-speed) mode is entered. If the LSON bit in SYSCR2
is set to 1 while the LSON bit in SYSCR1 is cleared to 0, a transition to active (medium-speed)
mode results from IRQ₀, IRQ₁ or WKP₇ to WKP₀ interrupts in standby mode, timer A, timer F,
IRQ₀, or WKP₇ to WKP₀ interrupts in watch mode, or any interrupt in sleep mode. A transition
to active (medium-speed) mode does not take place if the I bit of CCR is set to 1 or the particular
interrupt is disabled in the interrupt enable register.
Furthermore, it sometimes acts with half state early timing at the time of transition to active
(medium-speed) mode.
5.7.2 Clearing Active (Medium-Speed) Mode
Active (medium-speed) mode is cleared by a SLEEP instruction.
• Clearing by SLEEP instruction
A transition to standby mode takes place if the SLEEP instruction is executed while the SSBY bit
in SYSCR1 is set to 1, the LSON bit in SYSCR1 is cleared to 0, and the TMA3 bit in TMA is
cleared to 0. The system goes to watch mode if the SSBY bit in SYSCR1 is set to 1 and bit TMA3
in TMA is set to 1 when a SLEEP instruction is executed.
When both SSBY and LSON are cleared to 0 in SYSCR1 and a SLEEP instruction is executed,
sleep mode is entered. Direct transfer to active (high-speed) mode or to subactive mode is also
possible. See 5.8, Direct Transfer, below for details.
• Clearing by RES pin
When the RES pin is driven low, a transition is made to the reset state and active (medium-speed)
mode is cleared.
5.7.3 Operating Frequency in Active (Medium-Speed) Mode
Operation in active (medium-speed) mode is clocked at the frequency designated by the MA1 and
MA0 bits in SYSCR1.
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