ML610Q174 User’s ManualChapter 4 MCU Control FunctionFEUL610Q174-01 4-124.3.3 STOP ModeThe STOP mode is the state where low-speed oscillation and high-speed oscillation stop and the CPU and peripheralcircuits stop the operation.When the stop code acceptor is enabled by writing “5nH”(n: an arbitrary value) and “0AnH”(n: an arbitrary value) tothe stop code acceptor (STPACP) sequentially and the STP bit of the standby control register (SBYCON) is set to “1”,the STOP mode is entered. When the STOP mode is set, the stop code acceptor is disabled.When an interrupt-enabled (the interrupt enable flag is “1”) P00 to P03 interrupt request is issued, the STP bit is set to“0”, the STOP mode is released, and the mode is returned to the program run mode.4.3.3.1 STOP Mode When CPU Operates with Low-Speed ClockWhen the stop code acceptor is in the enabled state and the STP bit of SBYCON is set to “1”, the STOP mode isentered, stopping low-speed oscillation and high-speed oscillation.When the interrupt-enabled (the interrupt enable flag is “1”) P00 to P03 interrupt request is issued, the STP bit is set to“0” and low-speed oscillation restarts. If the high-speed clock was oscillating before the STOP mode is entered, thehigh-speed oscillation restarts. When the high-speed clock was not oscillating before the STOP mode is entered,high-speed oscillation does not start.When an interrupt request occurs, the STOP mode is released after counting a built-in RC oscillation clock 128 times.,the mode is returned to the program mode, and the low-speed clock(LSCLK) restarts supply to the peripheral circuits.If the high-speed clock already started oscillation at this time, the high-speed clocks (OSCLK and HSCLK) also restartsupply to the peripheral circuits. After waiting for low-speed crystal oscillation start time(TXTL ) and low-speed crystaloscillation stable time(8192-pulse count), the low-speed clock changes from a built-in RC oscillation clock to thelow-speed crystal oscillation clock. Simultaneously, low-speed oscillation clock change interruption (LOSCINT) isgenerated.Refer to appendix C, “Electrical Characteristics” for TXTL .Figure 4-3 shows the operation waveforms in STOP mode when CPU operates with the low-speed clock.Figure 4-3 Operation Waveforms in STOP Mode When CPU Operates with Low-Speed Clock4.3.3.2 STOP Mode When CPU Operates with High-Speed ClockSYSCLKOscillation waveformOscillation waveformHigh-speedoscillationwaveformSBYCON.STP bitLSCLKHSCLK waveform HSCLK waveformHSCLKProgram operating mode STOP mode Program operating modeInterrupt requestTXTLLow-speed clockpulse countHiz Oscillation waveformLow-speed crystaloscillationwaveformBuilt-in RCoscillation waveformBuilt-in RC oscillation128 pulse countLow-speed oscillation clock changeinterrupt request
