MC68HC05K0 Datasheet, PDF (61/154 Pages) Freescale Semiconductor, Inc – HCMOS Microcontroller Unit

Freescale Semiconductor, Inc.
Low-Power Modes
Wait Mode
6.4 Wait Mode
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.
These conditions restart the CPU clock and bring the MCU out of wait
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 mask option for the port A external interrupt function is
selected, a low-to-high transition on a PA3–PA0 pin loads the
program counter with the contents of locations $03FA and $03FB.
• A timer interrupt — A timer overflow or a real-time interrupt request
loads the program counter with the contents of locations $03F8
and $03F9.
• A COP watchdog reset — A timeout of the mask-optional COP
watchdog resets the MCU and loads the program counter with the
contents of locations $03FE and $03FF. Software can enable
real-time interrupts so that the MCU can periodically exit wait
mode to reset the COP watchdog.
• Low-voltage reset — A low-voltage detect resets the MCU and
loads the program counter with the contents of locations $03FE
and $03FF (if this mask option is selected).
• 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.
MC68HC05K0 • MC68HC05K1 — Rev. 2.0
Low-Power Modes
For More Information On This Product,
Go to: www.freescale.com
Technical Data