MC68HC705K1 Datasheet, PDF (58/140 Pages) Freescale Semiconductor, Inc – HCMOS Microcontroller Unit

Low-Power Modes
Freescale Semiconductor, Inc.
• Sets the IRQE bit in the IRQ status and control register to enable
external interrupts
• Clears the I bit in the condition code register, enabling interrupts
• Stops the internal oscillator, turning off the central processor unit
(CPU) clock and the timer clock, including the computer operating
properly (COP) watchdog
The STOP instruction does not affect any other registers or any
input/output (I/O) lines.
These conditions bring the MCU out of stop mode:
• An external interrupt signal on the IRQ/V_PP pin — A high-to-low
transition on the IRQ/V_PP pin loads the program counter with the
contents of locations $03FA and $03FB.
• An external interrupt signal on a port A external interrupt pin — If
the PIRQ bit in the mask option register is programmed to a
logic 1, a low-to-high transition on a PA3–PA0 pin loads the
program counter with the contents of locations $03FA and $03FB.
• External reset — A logic 0 on the RESET pin resets the MCU and
loads the program counter with the contents of locations $03FE
and $03FF.
When the MCU exits stop mode, processing resumes after a
stabilization delay of 4064 oscillator cycles.
6.4 Wait Mode
Technical Data
The WAIT instruction puts the MCU in an intermediate
power-consumption mode and has these effects on the MCU:
• Clears the I bit in the condition code register, enabling interrupts
• Sets the IRQE bit in the IRQ status and control register, enabling
external interrupts
• Stops the CPU clock, but allows the internal oscillator and timer
clock to continue to run
The WAIT instruction does not affect any other registers or any I/O lines.
Low-Power Modes
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MC68HC705K1 — Rev. 2.0