HCS08 datasheet(253/290 Pages) MOTOROLA

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Data Sheet — MC9S08GB60/D V1.5

MOTOROLA

253

MC9S08GB/GT

WS — Wait or Stop Status

When the target CPU is in wait or stop mode, most BDC commands cannot function. However, the

BACKGROUND command can be used to force the target CPU out of wait or stop and into active

background mode where all BDC commands work. Whenever the host forces the target MCU into

active background mode, the host should issue a READ_STATUS command to check that

BDMACT = 1 before attempting other BDC commands.

1 = Target CPU is in wait or stop mode, or a BACKGROUND command was used to change from

wait or stop to active background mode.

0 = Target CPU is running user application code or in active background mode (was not in wait or

stop mode when background became active).

WSF — Wait or Stop Failure Status

This status bit is set if a memory access command failed due to the target CPU executing a wait or stop

instruction at or about the same time. The usual recovery strategy is to issue a BACKGROUND

command to get out of wait or stop mode into active background mode, repeat the command that failed,

then return to the user program. (Typically, the host would restore CPU registers and stack values and

re-execute the wait or stop instruction.)

1 = Memory access command failed because the CPU entered wait or stop mode.

0 = Memory access did not conflict with a wait or stop instruction.

DVF — Data Valid Failure Status

This status bit is not used in the MC9S08GB/GT because it does not have any slow access memory.

1 = Memory access command failed because CPU was not finished with a slow memory access.

0 = Memory access did not conflict with a slow memory access.

15.5.1.2 BDC Breakpoint Match Register (BDCBKPT)

This 16-bit register holds the address for the hardware breakpoint in the BDC. The BKPTEN and FTS

control bits in BDCSCR are used to enable and configure the breakpoint logic. Dedicated serial BDC

commands (READ_BKPT and WRITE_BKPT) are used to read and write the BDCBKPT register but is

not accessible to user programs because it is not located in the normal memory map of the MCU.

Breakpoints are normally set while the target MCU is in active background mode before running the user

application program. For additional information about setup and use of the hardware breakpoint logic in

the BDC, refer to 15.3.4 BDC Hardware Breakpoint.

15.5.2 System Background Debug Force Reset Register (SBDFR)

This register contains a single write-only control bit. A serial active background mode command such as

WRITE_BYTE must be used to write to SBDFR. Attempts to write this register from a user program are

ignored. Reads always return $00.

HCS08 데이터시트(PDF) 253 Page - Motorola, Inc