Debugging options

New in version 3.4.

See also

Please make sure to read PIO Unified Debugger guide first.


A name of debugging tool. This option is useful when board supports more than one debugging tool (adapter, probe) or you want to create Custom debugging configuration.

See available tools in Tools & Debug Probes.


platform = ...
board = ...
debug_tool = custom


An initial breakpoint that makes your program stop whenever a certain point in the program is reached. Default value is set to tbreak main and means creating a temporary breakpoint at int main(...) function and automatically delete it after the first time a program stops there.


Please note that each debugging tool (adapter, probe) has limited number of hardware breakpoints.

If you need more Project Initial Breakpoints, please place them in debug_extra_cmds.


platform = ...
board = ...

; Examples 1: disable initial breakpoint
debug_init_break =

; Examples 2: temporary stop at ``void loop()`` function
debug_init_break = tbreak loop

; Examples 3: stop in main.cpp at line 13
debug_init_break = break main.cpp:13

; Examples 4: temporary stop at ``void Reset_Handler(void)``
debug_init_break = tbreak Reset_Handler


Initial commands that will be passed to back-end debugger.

PlatformIO dynamically configures back-end debugger depending on a debug environment. Highly recommended to DO NOT override this option.

For example, the custom initial commands for GDB:

platform = ...
board = ...
debug_init_cmds =
  target extended-remote $DEBUG_PORT
  monitor reset halt
  monitor init
  monitor reset halt


Extra commands that will be passed to back-end debugger after initialization. For example, add custom breakpoint and load .gdbinit from a project directory for GDB:

platform = ...
board = ...
debug_extra_cmds =
  break main.cpp:13
  break foo.cpp:100
  source .gdbinit


Initial Project Breakpoints: Use break path/to/file:LINE_NUMBER to define initial breakpoints for debug environment. Multiple breakpoints are allowed.

To save session breakpoints, please use save breakpoints [filename] command in Debug Console. For example, save breakpoints .gdbinit. Later, this file could be loaded via source [filename] command. See above.


Specify a command which will be used to load program/firmware to a target device. Possible options:

  • load - default option
  • some command - pass any debugging client command (GDB, etc.)
  • load address - load program at specified address, where “address” should be a valid number
  • preload - some embedded devices have locked Flash Memory (a few Freescale Kinetis and NXP LPC boards). In this case, firmware loading using debugging client is disabled. preload command instructs PlatformIO Core (CLI) to load program/firmware using development platform “upload” method (via bootloader, media disk, etc)
  • (empty value, debug_load_cmd =), disables program loading at all.


Allows one to control when PlatformIO should load debugging firmware to the end target. Possible options:

  • always - load for the each debugging session, default
  • modified - load only when firmware was modified
  • manual - do not load firmware automatically. You are responsible to pre-flash target with debugging firmware in this case.


Allows one to setup a custom debugging server. By default, boards are pre-configured with a debugging server that is compatible with “on-board” debugging tool (adapter, probe). Also, this option is useful for a Custom debugging tool.

Option format (multi-line):

  • First line is an executable path of debugging server
  • 2-nd and the next lines are arguments for executable file


platform = ...
board = ...
debug_server =


A debugging port of a remote target. Could be a serial device or network address. PlatformIO detects it automatically if is not specified.

For example:

  • /dev/ttyUSB0 - Unix-based OS
  • COM3 - Windows OS
  • localhost:3333


A custom path to SVD file which contains information about device peripherals.