Breakpoint Set - Motorola M68EVB912B32 User Manual

OPERATION
BR

Breakpoint Set

BR
syntax:
BR [<Address> <Address> ...]
where:
<Address> are optional 16-bit hexadecimal numbers.
The BR command is used to set a software breakpoint at a specified address or to display any
previously set breakpoints. The function of a breakpoint is to halt user program execution when
the program reaches the breakpoint address. When a breakpoint address is encountered,
D-Bug12 disassembles the instruction at the breakpoint address, prints the CPU12's register
contents, and waits for a D-Bug12 command to be entered by the user.
Breakpoints are set by typing the breakpoint command followed by one or more breakpoint
addresses. Entering the breakpoint command without any breakpoint addresses will display all
the currently set breakpoints.
A maximum of 10 user breakpoints may be set at one time.
restrictions:
D-Bug12 implements the breakpoint function by replacing the opcode at the breakpoint address
in the users program with an SWI instruction when operating in EVB mode or with the BGND
instruction when operating in POD mode. A breakpoint may not be set on a user SWI instruction
when operating in EVB mode. In either mode, breakpoints may only be set at an opcode address,
and breakpoints may only be placed at memory addresses in alterable memory.
Even though D-Bug12 supports a maximum of 10 user-defined breakpoints, a maximum of 9
breakpoints may be set on the command line at one time. This restriction is due to the limitation
of the command-line processor, which allows a maximum of 10 command-line arguments,
including the command string.
When operating in POD mode, new breakpoints may not be set with the BR command when the
"R>" prompt is displayed. However, the BR command may be used to display breakpoints that
are currently set in the user's running program.
D-Bug12 version 2.0.0 does not support the MC68HC912B32's hardware breakpoint (H/W)
function. Later versions of D-Bug12, which may support this function, can be obtained from the
sources listed in Obtaining D-Bug12 Upgrades on page E-6.
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