Table of Contents
Advertisement
CHAPTER 8 LOW-POWER CONTROL CIRCUIT
■ Release of Stop Mode
The low-power consumption control circuit releases the stop mode when a reset is input or an interrupt
occurs. Because oscillation of the operating clock is halted before returning from the stop mode, the low-
power consumption control circuit enters the oscillation stabilization wait state, then releases the stop
mode.
●
Return by a reset
After the stop mode is released by a reset, the oscillation stabilization wait state is set. The reset sequence is
executed after the oscillation stabilization wait time.
Note:
The RST signal must be asserted for at least 100 μs + oscillation time of the oscillator + 16 machine
clock cycles in Stop Mode. Refer to the AC Characteristics Section of the data sheet.
●
Return by an interrupt
If an interrupt request of level seven or higher is issued from a peripheral circuit during the stop mode (IL2,
IL1, and IL0 of the interrupt control register (ICR) do not indicate "111
mode control circuit releases the stop mode. The interrupt is then handled as an ordinary interrupt after the
oscillation stabilization wait time of the main clock specified by the WS1 and WS0 bits of the clock
selection register (CKSCR). If the interrupt is accepted according to the setting of the I flag of the condition
code register (CCR), interrupt level mask register (ILM), and interrupt control register (ICR), the CPU
executes the interrupt processing. If the interrupt is not accepted, the CPU executes the instruction
following the instruction specifying the stop mode.
Note:
When interrupt processing is executed, the CPU normally executes the instruction following the
instruction in which switching to the stop mode has been specified. The CPU then proceeds to
interrupt processing. If the switching to the stop mode and acceptance of an external bus hold
request occur at the same time, however, the CPU may proceed to interrupt processing before
executing the next instruction.
Figure 8.5-2 shows the release of the stop mode (external reset).
154
"), the low-power consumption
B
Advertisement
Table of Contents
