Intel IQ80321 B.9 Debugging Basics

102 Board Manual

Intel® IQ80321 I/O Processor Evaluation Platform

Getting Started and Debugg er

B.9 Debugging Basics

Debuggers allo w developers to interrogate application code by allowing program flow control, da ta

observation, and data manipulation. The f low control functions include the abilit y to single-step

through the code, step into functions, step over functions, and run to b reakpoint (hardware or

software). The data observation and manipulation functions include acces s to memory, registers, and

variables. The combination of th e flow control and data funct ions allows the developer to d ebug

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. Debuggers can give insight that is difficult

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

functionality. They are intrusive by definition. They are software prog rams that interact with software

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

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

The following section provides a brief overview of breakpoints. See the Int el® 80321 I/O Processor

Developer’s Manual, for more detailed informati on.

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

software breakpoints were see n in Section B.7 of this Guide. Program execution can be halte d at a

particular line of code, stepped thr ough, and executed again to the next breakpoint via debug gers.

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

useful pieces of informati on can be monitored.

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

stacks, or other target information. Hardware br eakpoints handle difficult issues, by providing the

ability to set the processor conditions that cause the program to halt. Use hardware breakpoints to

locate problems such as reentrance, obscure timing, etc.

The 80321 contains two instruction breakpoint address registers (IBCR0 an d IBCR1), one data

breakpoint address registe r (DBR0), one configurable d ata mask/address register (D BR1), and one

data breakpoint control register (DBCON). The 80321 also supports a 2 56 entry, trace buffer, that

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