M30222 Datasheet, PDF (25/237 Pages) Mitsubishi Electric Semiconductor – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

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Specifications in this manual are tentative and subject to change
MITSUBISHI MICROCOMPUTERS
M30222 Group
Rev. G
Wait Mode
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
Wait Mode
When a WAIT instruction is executed, the BCLK stops and the microcomputer enters the wait mode. In
this mode, oscillation continues but the BCLK and Watchdog timer stop. Writing “1” to the WAIT periph-
eral function clock stop bit and executing a WAIT instruction stops the clock being supplied to the
internal peripheral functions, allowing power dissipation to be reduced. Table 1.11 shows the status of
the ports in wait mode.
Wait mode is cancelled by a hardware reset or an interrupt. If an interrupt is used to cancel wait mode,
the microcomputer restarts from the interrupt routine using as BCLK, the clock that had been selected
when the WAIT instruction was executed.
Usage Precautions
When switching to either wait mode or stop mode, instructions occupying four bytes either from the WAIT
instruction or from the instruction that sets the every-clock stop bit to “1” within the instruction queue are
prefetched and then the program stops. So put at least four NOPs in succession either to the WAIT instruc-
tion or to the instruction that sets the every-clock stop bit to “1”.
Table 1.11. Port Status during wait mode
Pin
Port
CLKOUT/P75
Mode
When fC1 selected
When f1, clock divided
counter output selected
Single-chip mode
Retains status before wait mode
Does not stop
Retains status before stop mode.
Does not stop when the WAIT
peripheral function clock stop bit is "0".
When the WAIT peripheral function
clock stop bit is "1", the status im-
mediately prior to entering wait mode
is maintained.
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