HD404374FT datasheet(46/161 Pages) RENESAS

46 / 161 page

HD404374/HD404384/HD404389/HD404082/HD404084 Series

Rev.5.00, Sep.11.2003, page 46 of 161

Active mode:

In active mode all functions operate. In this mode, the MCU operates on clocks generated by the OSC

1 and

OSC

2 oscillator circuits.

Standby mode:

In standby mode the oscillators continue to operate but clocks relating to instruction execution halt. As a

result, CPU operation stops, and registers, RAM, and the D port/R port set for output retain their state

immediately prior to entering standby mode. Interrupts, timers, the serial interface, and other peripheral

functions continue to operate.

Power consumption is lower than in active mode due to the halting of the CPU.

The MCU is switched to standby mode by executing the SBY instruction in active mode. Standby mode is

cleared by

RESET input or an interrupt request. When standby mode is cleared by RESET input, an MCU

reset is performed. When standby mode is cleared by an interrupt request, the MCU enters active mode and

executes a instruction following the SBY instruction. After executing the instruction, if the interrupt enable

flag is set to 1, interrupt handling is executed; if the interrupt enable flag is cleared to 0, the interrupt

request is held pending and normal instruction execution is continued.

MCU operation flowchart is shown in figure 12.

HD404374FT Datasheet(PDF) 46 Page - Renesas Technology Corp