MC3S12RG128 Datasheet, PDF (212/546 Pages) Freescale Semiconductor, Inc – Microcontrollers

Chapter 7 Breakpoint Module (BKPV1) Block Description
In all cases, BDM related breakpoints will have priority over those generated by the Breakpoint sub-block.
This priority includes breakpoints enabled by the TAGLO and TAGHI external pins of the system that
interface with the BDM directly and whose signal information passes through and is used by the
Breakpoint sub-block.
NOTE
BDM should not be entered from a breakpoint unless the BKEN bit is set in
the BDM. Even if the ENABLE bit in the BDM is negated, the CPU actually
executes the BDM firmware code. It checks the ENABLE and returns if
enable is not set. If the BDM is not serviced by the monitor then the
breakpoint would be re-asserted when the BDM returns to normal CPU
flow.
There is no hardware to enforce restriction of breakpoint operation if the
BDM is not enabled.
MC3S12RG128 Data Sheet, Rev. 1.05
212
Freescale Semiconductor