HCS08 datasheet(254/290 Pages) MOTOROLA

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Development Support

MC9S08GB/GT

254

MOTOROLA

Figure 15-6 System Background Debug Force Reset Register (SBDFR)

BDFR — Background Debug Force Reset

A serial active background mode command such as WRITE_BYTE may be used to allow an external

debug host to force a target system reset. Writing logic 1 to this bit forces an MCU reset. This bit

cannot be written from a user program.

15.5.3 DBG Registers and Control Bits

The debug module includes nine bytes of register space for three 16-bit registers and three 8-bit control

and status registers. These registers are located in the high register space of the normal memory map so

they are accessible to normal application programs. These registers are rarely if ever accessed by normal

user application programs with the possible exception of a ROM patching mechanism that uses the

breakpoint logic.

15.5.3.1 Debug Comparator A High Register (DBGCAH)

This register contains compare value bits for the high-order eight bits of comparator A. This register is

forced to $00 at reset and can be read at any time or written at any time unless ARM = 1.

15.5.3.2 Debug Comparator A Low Register (DBGCAL)

This register contains compare value bits for the low-order eight bits of comparator A. This register is

forced to $00 at reset and can be read at any time or written at any time unless ARM = 1.

15.5.3.3 Debug Comparator B High Register (DBGCBH)

This register contains compare value bits for the high-order eight bits of comparator B. This register is

forced to $00 at reset and can be read at any time or written at any time unless ARM = 1.

15.5.3.4 Debug Comparator B Low Register (DBGCBL)

This register contains compare value bits for the low-order eight bits of comparator B. This register is

forced to $00 at reset and can be read at any time or written at any time unless ARM = 1.

Bit 7

654321

Bit 0

Read:

00000000

Write:

BDFR(1)

NOTES:

1. BDFR is writable only through serial active background mode debug commands, not from user programs.

Reset:

00010000

= Unimplemented or Reserved

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