R8C/10 Group
Rev.1.20 Jan 27, 2006 page 26 of 180
REJ09B0019-0120
6.4.3 Stop Mode
In stop mode, all oscillator circuits are turned off, so are the CPU clock and the peripheral function
clocks. Therefore, the CPU and the peripheral functions clocked by these clocks stop operating. The
least amount of power is consumed in this mode. If the voltage applied to Vcc pin is VRAM or more, the
internal RAM is retained.
However, the peripheral functions clocked by external signals keep operating. The following interrupts
can be used to exit stop mode.
• Key interrupt
______ ______ ______
• INT0 to INT2 interrupts (INT0 can be used only when there is no filter.)
• Timer X interrupt (when counting external pulses in event counter mode)
• Timer Y interrupt (when counting inputs from CNTR1 pin in timer mode)
• Serial interface interrupt (when external clock is selected)
• Entering Stop Mode
The microcomputer is placed into stop mode by setting the CM10 bit of CM1 register to “1” (all clocks
turned off). At the same time, the CM06 bit of CM0 register is set to “1” (divide-by-8 mode) and the
CM15 bit of CM10 register is set to “1” (main clock oscillator circuit drive capacity high).
Before entering stop mode, set the OCD1 to OCD0 bits to “002” (oscillation stop detection function
disable).
• Pin Status in Stop Mode
The status before wait mode is retained.
However, the XOUT(P47) pin is held “H” when the CM13 bit in the CM1 register is set to “1” (XIN-XOUT
pin). The P47(XOUT) is in input state when the CM13 bit is set to “0” (input port P46, P47).
• Exiting Stop Mode
The microcomputer is moved out of stop mode by a hardware reset or peripheral function interrupt.
When using a hardware reset to exit stop mode, set the ILVL2 to ILVL0 bits for the peripheral function
interrupts to “0002” (interrupts disabled) before setting the CM10 bit to “1”.
When using a peripheral function interrupt to exit stop mode, set up the following before setting the
CM10 bit to “1”.
1. In the ILVL2 to ILVL0 bits in the interrupt control register, set the interrupt priority level of the
peripheral function interrupt to be used to exit stop mode.
Also, for all of the peripheral function interrupts not used to exit stop mode, set the ILVL2 to ILVL0
bits to “0002”.
2. Set the I flag to “1”.
3. Enable the peripheral function whose interrupt is to be used to exit stop mode.
In this case, when an interrupt request is generated and the CPU clock is thereby turned on, an
interrupt sequence is executed.
The main clock divided by 8 of the clock which is used right before stop mode is used for the CPU
clock when exiting stop mode by a peripheral function interrupt.
6.4 Power Control
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