Intel IQ80321 C.9 Debugging Basics

Board Manual 119

Intel® IQ80321 I/O Processor E valuation Platform

Getting Started and Debugger

C.9 Debugging Basics

Debuggers allow developer s to interrogate application co de by allowing program flow c ontrol, data

observation, and data manipulation. The flow control functions include the ability to sing le-step

through the code, step into fu nctions, step over functions , and run to breakpoint (ha rdware or

software). The data observation and manipulation functions include access to mem ory, registers, and

variables. The combination of the flow con trol and data functions allows the develop er to debug

problems as they occur or to validate the application code. As the size of an ap plication grows, the

need to be able to narrow down the cause of a problem to a few lines of code is imperative.

Debuggers have a finite set of capabilities and limitations. Debu ggers can give insight that is difficult

to obtain without them, but they can fail wh en they are not used within the limits of their

functionality. They are intrusive by defi nition. They are software programs that interact with s oftware

monitors or hardware (JTAG) to control a target program. U ltimately, the debugger works best when

the developer understands wha t it can and can not do and uses it within those constraints.

The following section provide s a brief overview of breakp oints. See the Intel® 80321 I/O Processor

Developer’s Manual, for more detailed information.

Software breakpoints are setup and utilized via debugger utilities ( such as Code|Lab). The abilities of

software breakpoints were seen in SectionC.7 of this Guide. Program execu tion can be halted at a

particular line of code, stepp ed through, and executed agai n to the next breakpoint via de buggers.

During this process, register values, memory address contents, variable contents, and man y other

useful pieces of information can be monitored.

Hardware breakpoints step and breakpoint in code in either ROM or RA M without altering the code,

stacks, or other target informa tion. Hardware breakpoin ts handle difficult issues, by pr oviding the

ability to set the processor conditions tha t cause the program to halt. Use hardware break points to

locate problems such as reentrance, obscure timing, etc.

The 80321 contains two instru ction breakpoint address reg isters (IBCR0 and IBCR1), one data

breakpoint address register (DBR0), one configurable data mask/address register (DBR1), and one

data breakpoint control register (DBCON). The 80321 also supports a 256 entr y, trace buffer, that

records program execution information. The registers to control the trace bu ffer are located in CP14.