SH7730 Datasheet, PDF(527/1188 Page) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7780 Series

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SH7730 Datasheet, PDF (527/1188 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7780 Series

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Section 14 Reset and Power-Down Modes

14.4.3 Software Standby Mode

(1) Transition to Software Standby Mode

Executing the SLEEP instruction when the STBY bit in STBCR is 1 causes a transition from the

program execution state to software standby mode. In software standby mode, not only the CPU

but also the clock and on-chip peripheral modules halt. The clock output from the CKO pin also

halts. The RWDT that operates on the RCLK clock, however, continues to operate. The functions

of the VCC supplied (I/O) region that needs no clock (such as detection of NMI and IRQ interrupts)

also continue to operate.

The contents of the CPU and cache registers remain unchanged. For the register states of the on-

chip peripheral modules in software standby mode, refer to the register descriptions in each

section.

The procedure for a transition to software standby mode is as follows:

1. Set the STBY bit in STBCR to 1.

2. Execute the SLEEP instruction.

3. Software standby mode is entered and the clocks within the LSI are halted. The output of the

STATUS0 pin goes high.

(2) Exit from Software Standby Mode

Exit from software standby mode is driven by an interrupt (NMI, IRQ, CMT, or KEYSC), or a

power-on reset.

(a) Exit Driven by an Interrupt

When the clock is an externally input signal or from the internal crystal oscillator and the

oscillation is not stopped in software standby mode, an NMI, IRQ, CMT, or KEYSC interrupt will

trigger exit from software standby mode and make the STATUS0 pin go low.

When the internal crystal oscillator is used as the clock supply source and the oscillator is stopped

in software standby mode, only the NMI interrupt can trigger exit from software standby mode, in

which case the STATUS0 pin goes low. Note that exit from software standby mode cannot be

driven by the IRQ, PINT, or RTC interrupts when the internal crystal oscillator has been stopped.

Rev. 1.00 Sep. 19, 2007 Page 479 of 1136

REJ09B0359-0100

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