HD6432621 Hitachi, HD6432621 Datasheet - Page 742

• Manufacturer Part Number: HD6432621
• Description: (HD64F262x Series) 16-Bit Microcomputer
• Manufacturer: Hitachi

21A.5.2 Usage Notes
DTC Module Stop: Depending on the operating status of the DTC, the MSTPA7 and MSTPA6
bits may not be set to 1. Setting of the DTC module stop mode should be carried out only when
the respective module is not activated.
For details, refer to section 8, Data Transfer Controller (DTC).
On-Chip Supporting Module Interrupt: Relevant interrupt operations cannot be performed in
module stop mode. Consequently, if module stop mode is entered when an interrupt has been
requested, it will not be possible to clear the CPU interrupt source or the DTC activation source.
Interrupts should therefore be disabled before entering module stop mode.
Writing to MSTPCR: MSTPCR should only be written to by the CPU.
21A.6 Software Standby Mode
21A.6.1 Software Standby Mode
A transition is made to software standby mode when the SLEEP instruction is executed when the
SBYCR SSBY bit = 1. In this mode, the CPU, on-chip supporting modules, and oscillator all stop.
However, the contents of the CPU’s internal registers, RAM data, and the states of on-chip
supporting modules other than the SCI, A/D converter, HCAN and I/O ports, are retained.
Whether the address bus and bus control signals are placed in the high-impedance state or retain
the output state can be specified by the OPE bit in SBYCR.
In this mode the oscillator stops, and therefore power dissipation is significantly reduced.
21A.6.2 Clearing Software Standby Mode
Software standby mode is cleared by an external interrupt (NMI pin, or pins IRQ0 to IRQ5), or by
means of the RES pin or STBY pin.
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Clearing with an interrupt
When an NMI or IRQ0 to IRQ5 interrupt request signal is input, clock oscillation starts, and
after the elapse of the time set in bits STS2 to STS0 in SYSCR, stable clocks are supplied to
the entire chip, software standby mode is cleared, and interrupt exception handling is started.
When clearing software standby mode with an IRQ0 to IRQ5 interrupt, set the corresponding
enable bit to 1 and ensure that no interrupt with a higher priority than interrupts IRQ0 to IRQ5
is generated. Software standby mode cannot be cleared if the interrupt has been masked on the
CPU side or has been designated as a DTC activation source.