Stop Mode - Renesas M16C/64A Series User Manual

M16C/64A Group
9.3.4

Stop Mode

In stop mode, all oscillator are stopped, so the CPU clock and peripheral function clocks are also
stopped. Therefore, the CPU and the peripheral functions using these clocks stop operating. The least
amount of power is consumed in this mode. If the voltage applied to pins VCC1 and VCC2 is VRAM or
greater, the contents of internal RAM are retained. When applying 2.7 V or less to pins VCC1 and
VCC2, make sure VCC1 ≥ VCC2 ≥ VRAM.
However, the peripheral functions activated by external signals keep operating.
9.3.4.1 Entering Stop Mode
The MCU enters stop mode by setting the CM10 bit in the CM1 register to 1 (all clocks turned off). At
the same time, the CM06 bit in the CM0 register becomes 1 (divide-by-8 mode), and the CM15 bit in
the CM1 register becomes 1 (main clock oscillator drive capability high).
Before entering stop mode, set the CM20 bit to 0 (oscillator stop/restart detect function disabled).
When the CM11 bit is 1 (PLL clock used as the CPU clock source), set the CM11 bit to 0 (main clock
used as the CPU clock source), and then the PLC07 bit to 0 (PLL turned off) before entering stop
mode.
When using stop mode, set the following:
(1) Set the I flag to 0.
(2) Set the interrupt priority level of bits ILVL2 to ILVL0 in the interrupt control register for the
peripheral function interrupt which is used to exit stop mode. Start the peripheral function which
is used to stop mode if it is stopped.
(3) Set 000b (interrupt disabled) to bits ILVL2 to ILVL0 in the interrupt control registers for the
peripheral function interrupts not used to exit stop mode.
(When using any of the following resets or interrupts to exit stop mode, set 000b to bits ILVL2 to
ILVL0 in all interrupt control registers for peripheral function interrupts: hardware reset, voltage
monitor 0 reset, NMI interrupt, voltage monitor 1 interrupt, or voltage monitor 2 interrupt)
(4) Set the I flag to 1.
(5) Set the CM10 bit in the CM1 register to 1.
9.3.4.2 Pin Status in Stop Mode
Table 9.7 lists Pin Status in Stop Mode.
Table 9.7 Pin Status in Stop Mode
Pin
A0 to A19, D0 to D15,
CS0 to CS3 , BHE
RD , WR , WRL , WRH
HLDA , BCLK
ALE
I/O ports
f1, f8, f32, fC
CLKOUT
selected
XOUT
XCIN, XCOUT
R01UH0136EJ0210 Rev.2.10
Jul 31, 2012
Memory Expansion Mode
Microprocessor Mode
Retains status just prior to stop mode
High
High
Undefined
Retains status just prior to stop mode Retains status just prior to stop mode
Cannot be used as CLKOUT pin
High
High-impedance
9. Power Control
Single-Chip Mode
Cannot be used as bus control pin
Retains status just prior to stop mode
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