Freescale Semiconductor, Inc.
Op e ra ting Mod e s
6.3 Sing le -Chip Mod e
In single-chip mode, the address and data buses are not available
externally, but there are three 8-bit input/output (I/O) ports and one 7-bit
I/O port. This mode allows the MCU to function as a self-contained
microcontroller, with maximum use of the pins for on-chip peripheral
functions. All address and data activity occurs within the MCU. Single-
chip mode is entered on the rising edge of RESET if the IRQ pin is within
normal operating range.
6.4 Low-Powe r Mod e s
The following paragraphs describe the low-power modes.
6.4.1 Stop Mod e
The STOP instruction places the MCU in its lowest power-consumption
mode. In stop mode, the internal oscillator is turned off, halting all
internal processing, including timer operation.
During stop mode, the CTCSR ($08) bits are altered to remove any
pending timer interrupt request and to disable any further timer
interrupts. The timer prescaler is cleared. The I bit in the CCR is cleared
to enable external interrupts. All other registers and memory remain
unaltered. All input/output lines remain unchanged. The processor can
be brought out of stop mode only by an external interrupt or reset.
General Release Specification
MC68HC05CT4 — Rev. 2.0
Operating Modes
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