SH7706 Datasheet, PDF (624/749 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH™ RISC engine Family/SH7700 Series

Section 22 Power-Down Modes
Clock Pause Function
In software standby mode, the clock input from the EXTAL pin or CKIO pin can be halted and the
frequency can be changed. This function is used as follows:
1. Enter software standby mode using the appropriate procedures.
2. Once software standby mode is entered and the clock stopped within the chip, the STATUS1
pin output is low and the STATUS0 pin output is high.
3. Once the STATUS1 pin goes low and the STATUS0 pin goes high, the input clock is stopped
or the frequency is changed.
4. When the frequency is changed, an NMI, IRL, IRQ or on-chip supporting module (except the
internal timer) interrupt is input after the change. When the clock is stopped, the same
interrupts are input after the clock is applied.
5. After the time set in the WDT has elapsed, the clock starts being applied internally within the
chip, the STATUS1 and STATUS0 pins both go low, interrupts are handled, and operation
resumes.
22.3.3 Module Standby Function
Transition to Module Standby Function
Setting the standby control register MSTP8 to MSTP4, MSTP2 to MSTP0 bits to 1 halts the
supply of clocks to the corresponding on-chip supporting modules. This function can be used to
reduce the power consumption in normal mode and sleep mode. The module standby function
holds the state prior to halt of the external pins of the on-chip supporting modules. TMU external
pins hold their state prior to the halt. SCI external pins go to the reset state. With a few exceptions,
all registers hold their values.
If the realtime clock (RTC) is set to module standby mode (bit 1 in standby control register
(STBCR) set to 1) before any register in the RTC, SCI, or TMU is accessed, registers in the serial
communication interface (SCI) or timer unit (TMU) may not be read properly. To avoid this
problem, access (read or write) any register in the RTC, SCI, or TMU once or more before setting
the RTC to module standby mode.
Rev. 5.00 May 29, 2006 page 576 of 698
REJ09B0146-0500