Breakpoint Commands

To display information about the breakpoints commands available in MDB, type help breakpoints. The following table provides additional information for this class of commands

Table 1. Breakpoint Commands
Command Description
Break Sets a breakpoint at the specified source line number.

Command format:

break filename:linenumber [passCount]


break newmain.c:142 4

Sets a breakpoint at an absolute address.

Command format:

break *address [passCount]

  • address – the address of the program memory to break on – use the command: 'print /a' to get a symbol address.
  • passCount – the parameter is optional. Indicates the number of times the break ‘on condition’ is met before the program halts.


break *0x9d0000cc 5

MDB assigns a breakpoint number and returns:Breakpoint 0 at 0x9d0000cc: file newmain.c, line 16.

Sets a breakpoint at the beginning of the function.

Command format:

break function_name [passCount]


break function_foo 5

Delete Deletes a breakpoint – if no argument is specified, this deletes all breakpoints.

You can abbreviate this command as d.

Command format:

delete [breakpoint number]

d [breakpoint number]

The breakpoint number is generated by MDB for the Break and/or Watch commands.


delete or D

delete 1 or d 1

Halt Stops the debugger program.
Watch Sets a data breakpoint at the specified memory address, variable name, or an SFR (special function register).

Command format:

Watch address breakonType[:value] [passCount]

  • address – the name of a global variable, SFR, or data memory address to be watched.

    Use command 'print /a' to get a variable address.

  • breakonType:

    R -- Read.

    W -- Write.

    RW -- Read or Write.

  • value – this parameter is optional. If it is specified, the program will break only when the value held in the data memory matches the specified value.
  • passCount – this parameter is optional. The number of times the breakon condition is met before the program breaks.


watch 0xa0007ff0 R:0xf 1

watch 0xa0007ff0 R:10 1

watch my_Variable W 4

MDB will assign and return the watchpoint number, for example: Watchpoint 1.