MC9S08DZ16 FREESCALE [Freescale Semiconductor, Inc], MC9S08DZ16 Datasheet - Page 36

• Manufacturer Part Number: MC9S08DZ16
• Description: 8-Bit HCS08 Central Processor Unit (CPU)
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

Chapter 3 Modes of Operation
Background commands are of two types:
The active background mode is used to program a bootloader or user application program into the Flash
program memory before the MCU is operated in run mode for the first time. When the MC9S08DZ60
Series is shipped from the Freescale Semiconductor factory, the Flash program memory is erased by
default unless specifically noted so there is no program that could be executed in run mode until the Flash
memory is initially programmed. The active background mode can also be used to erase and reprogram
the Flash memory after it has been previously programmed.
For additional information about the active background mode, refer to the
3.5
Wait mode is entered by executing a WAIT instruction. Upon execution of the WAIT instruction, the CPU
enters a low-power state in which it is not clocked. The I bit in CCR is cleared when the CPU enters the
wait mode, enabling interrupts. When an interrupt request occurs, the CPU exits the wait mode and
resumes processing, beginning with the stacking operations leading to the interrupt service routine.
While the MCU is in wait mode, there are some restrictions on which background debug commands can
be used. Only the BACKGROUND command and memory-access-with-status commands are available
when the MCU is in wait mode. The memory-access-with-status commands do not allow memory access,
but they report an error indicating that the MCU is in either stop or wait mode. The BACKGROUND
command can be used to wake the MCU from wait mode and enter active background mode.
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Non-intrusive commands, defined as commands that can be issued while the user program is
running. Non-intrusive commands can be issued through the BKGD/MS pin while the MCU is in
run mode; non-intrusive commands can also be executed when the MCU is in the active
background mode. Non-intrusive commands include:
— Memory access commands
— Memory-access-with-status commands
— BDC register access commands
— The BACKGROUND command
Active background commands, which can only be executed while the MCU is in active background
mode. Active background commands include commands to:
— Read or write CPU registers
— Trace one user program instruction at a time
— Leave active background mode to return to the user application program (GO)
Wait Mode
MC9S08DZ60 Series Data Sheet, Rev. 4
Development Support
Freescale Semiconductor
chapter.