Freescale Semiconductor MCF5480 - Manual (Page 312)

MCF548x Reference Manual, Rev. 3
8-62 Freescale Semiconductor
The data_breakpoint can be included as an optional part of an address breakpoint.
The ColdFire debug architecture was created to provide this set of functionality without requiring the
traditional connection to the external system bus. Rather, the functionality is provided using only a
connection to a Freescale-defined 26-pin debug connector. By providing the required debug signals in
customer-specific designs, standard third-party emulators can be used for debug of these designs.
NOTE
The baseline debug functionality is described in any of the ColdFire
MCF52xx User’s Manuals, which are available as PDF files at:
http://www.freescale.com/ColdFire/. As an example, see the debug section
of the MCF5272 User’s Manual located under MCF5272 Product
Information.
8.8.2 ColdFire Debug Revision B
During development of the Version 3 ColdFire design, there were a number of enhancements to the
original debug functionality requested by customers and third-party developers. These requests resulted in
an expanded set of debug functionality named Revision B.
The Rev. B enhancements are as follows:
• Addition of a BDM SYNC _ PC command to display the processor’s current PC
• Creation of more flexible hardware breakpoint triggers, i.e., support for “OR” combinations
• Removal of the restrictions involving concurrent hardware breakpoint use and BDM command
activity
• Redefinition of the processor status values for the RTS instruction
• An external mechanism to generate a debug interrupt
• A mechanism to inhibit debug interrupts after the RTE exit
• A mechanism to identify the revision level of the debug module
Rev. B enhancements provide backward compatibility with the original design.
8.8.3 ColdFire Debug Revision C
Continuing discussions with customers and the developer community led to Revision C design
enhancements primarily related to improvements in the real-time debug capabilities of the ColdFire
architecture. The remainder of this section details these enhancements.
8.8.3.1 Debug Interrupts and Interrupt Requests (Emulator Mode)
In Rev. A and Rev. B ColdFire debug implementations, the response to a user-defined breakpoint trigger
can be configured to be one of three possibilities:
• The breakpoint trigger can merely be displayed on the DDATA bus, with no internal reaction to the
trigger. The trigger state information is displayed on DDATA in all situations.
• The breakpoint trigger can force the processor to halt and allow BDM activities.
• The breakpoint trigger can generate a special debug interrupt to allow real-time systems to quickly
process the interrupt and return to normal system executing as rapidly as possible.
The occurrence of the debug interrupt exception is treated as a special type of interrupt. It is considered to
be higher in priority than all normal interrupt requests and has special processor status values to provide
an external indication that this interrupt has occurred.