FR60 MB91460E Series - Microcontrollers - Fujitsu

MB91460E Series
4.2. Recovery from shutdown mode
The following factors are available to recover from the shutdown state:
• Assert the reset signal at the INITX terminal for minimum 10 ms 12
• Input of a valid recovery request via an external interrupt terminal
• Real Ttime Clock Interrupt (when RTC interrupt is enabled)
• Hardware Watchdog reset (when HWWD is enabled in STOP mode)
• Main Clock Supervisor reset (when Main oscillator is running and Main Clock Supervisor is enabled and
recovery by HWWD is enabled)
Shutdown state is released when a valid recovery factor is permitted. After the Shutdown state release, the
device restarts with a settings initialization reset (INIT), just like power-up operation. Only the Real Time Clock,
the Oscillation Stabilization settings in STCR register, and the recovery source flags in the Shutdown registers
EXTF and SHDINT are not cleared.
The internal restart sequence is as follows:
1. Resume the internal power supply.
2. Reset and assert the initialization reset (INIT).
3. Wait for oscillation stabilization.
4. Start the reset sequence.
As the external interrupt source flags and the RTC flag are retained in EXTF and SHDINT registers, it is possible
to determine whether it is power-up operation or recovery from shutdown state by checking the flags.
4.2.1. The Real Time Clock at Recovery from Shutdown
In normal operation, the registers and settings of the Real Rime Clock are initialized by Software Reset (RST).
At recovery from Shutdown, the RTC is not initialized:
• The prescaler, second, minute and hour counters continue counting also during the recovery INIT state.
• The clock selection for the RTC (by CSCFG.OSC1, CSCFG.OSC0) remains unchanged.
• The RTC interrupt enable bits and interrupt flags (in WTCR and WTCE registers) remain unchanged.
So at each recovery from Shutdown, the RTC continues running and the current time as well as the interrupt
flags can be read from the RTC after recovery.
Note: The Interrupt Control Register for RTC (ICR58), the Interrupt Level Mask (ILM) register as well as the Condition
Code Register (CCR, containing the I-Flag) are cleared by the recovery INIT, so that all interrupt processing
is disabled.
If the software re-enables interrupt processing by setting ICR58, ILM and I-Flag, the software will process
the pending RTC interrrupt immediately.
1. The minimum INTX=0 pulse length is determined by the time the main oscillator needs for stabilization.
2. Reset by INITX=0 will kill the ShutDown state and restart the device like at power-on.
88 DS705-00002-1v3-E