MC9S08JM16CGTE FREESCALE [Freescale Semiconductor, Inc], MC9S08JM16CGTE Datasheet - Page 32

• Manufacturer Part Number: MC9S08JM16CGTE
• Description: Microcontrollers
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

Chapter 3 Modes of Operation
After entering active background mode, the CPU is held in a suspended state waiting for serial background
commands rather than executing instructions from the user application program.
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 MC9S08JM16
series are shipped from the Freescale 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
Support.”
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 the condition code register (CCR) is cleared
when the CPU enters wait mode, enabling interrupts. When an interrupt request occurs, the CPU exits wait
mode and resumes processing, beginning with the stacking operations leading to the interrupt service
routine.
While the MCU is in wait mode, background debug commands can be used on the following restrictions.
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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 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)
Only the BACKGROUND command and memory-access-with-status commands are available
while 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 stop or wait mode.
The BACKGROUND command can be used to wake the MCU from wait mode and enter active
background mode.
Wait Mode
MC9S08JM16 Series Data Sheet, Rev. 2
Chapter 18, “Development
Freescale Semiconductor