options.md

Session options list

Note: The names of these options are expected to change before the 1.0 release of pyOCD, so they will be better normalized and grouped.

General options

Note that the project_dir, no_config, and config options must come from either a keyword argument or the options parameter passed to the Session constructor due to how early they are processed. The consequence of this is that these options cannot be set in a YAML config file.

Option Name	Type	Default	Description
adi.v5.max_invalid_ap_count	int	3	If this number of invalid APs is found in a row, then AP scanning will stop. The 'scan_all_aps' option takes precedence over this option if set.
allow_no_cores	bool	False	Prevents raising an error if no core were found after CoreSight discovery.
auto_unlock	bool	True	If the target is locked, it will by default be automatically mass erased in order to gain debug access. Set this option to False to disable auto unlock.
cache.read_code_from_elf	bool	True	Controls whether reads of code sections will be taken from an attached ELF file instead of the target memory. This can improve performance, especially over slow target connections. Requires an ELF file to be set.
chip_erase	str	'sector'	Whether to perform a chip erase or sector erases when programming flash. The value must be one of 'auto', 'sector', or 'chip'.
cmsis_dap.deferred_transfers	bool	True	Whether to use deferred transfers in the CMSIS-DAP probe backend. By disabling deferred transfers, all writes take effect immediately. However, performance is negatively affected.
cmsis_dap.limit_packets	bool	False	Restrict CMSIS-DAP backend to using a single in-flight command at a time. This is useful on some systems where USB is problematic, in particular virtual machines.
commander.history_length	int	1000	Number of entries in the pyOCD Commander command history. Set to -1 for unlimited.
config_file	str	See description	Relative path to a YAML config file that lets you specify session options either globally or per probe. The format of the file is documented above. The default is a pyocd.yaml or pyocd.yml file in the working directory.
connect_mode	str	'halt'	Controls how pyOCD connects to the target. One of 'halt', 'pre-reset', 'under-reset', 'attach'. 'halt': immediately halt all accessible cores upon connect. 'pre-reset': perform a hardware reset prior to connect and halt. 'under-reset': assert hardware reset during the connect sequence, then deassert after the cores are halted. This connect mode is often necessary to gain control of a target that is in a deep low power mode. 'attach': connect to a running target without halting cores.
cpu.step.instruction.timeout	float	0.0	Timeout in seconds for instruction step operations. The default of 0 means no timeout. Note that stepping may take a very long time for to return in cases such as stepping over a branch into the Secure world where the debugger doesn't have secure debug access, or similar for Privileged code in the case of UDE.
dap_protocol	str	'default'	Wire protocol, either 'swd', 'jtag', or 'default'.
dap_swj_enable	bool	True	Send SWJ transition sequence to switch between SWD and JTAG.
dap_swj_use_dormant	bool	False	When switching between SWD and JTAG, use the SWJ sequence added in ADIv5.2 that transitions through a new dormant state. Requires a SWJ-DPv2. Note that if the connection attempt fails using the deprecated sequence (when this option is disabled), then pyOCD will automatically attempt to use the new sequence. This option simply skips the deprecated sequence in case it causes problems or it is known that dormant state is required for the target.
debug.log_flm_info	bool	False	Log details of loaded .FLM flash algos.
debug.traceback	bool	True	Print tracebacks for exceptions.
enable_multicore_debug	bool	False	Whether to put pyOCD into multicore debug mode. The primary effect is to modify the default software reset type for secondary cores to use VECTRESET, which will fall back to emulated reset if the secondary core is not v7-M.
fast_program	bool	False	Setting this option to True will use CRC checks of existing flash sector contents to determine whether pages need to be programmed.
frequency	int	1000000 (1 MHz)	SWD/JTAG frequency in Hertz.
hide_programming_progress	bool	False	Disables flash programming progress bar when True.
keep_unwritten	bool	True	Whether to load existing flash content for ranges of sectors that will be erased but not written with new data.
logging	str, dict	No default	Either a dictionary with logging configuration, or a path to a separate yaml logging configuration file. See the logging configuration documentation for details of how to use this option.
no_config	bool	False	Do not use default config file.
pack	str, list of str	No default	Path or list of paths to CMSIS Device Family Packs. Devices defined in the pack(s) are added to the list of available targets.
probeserver.port	int	5555	TCP port for the debug probe server.
project_dir	str	See description	Path to the session's project directory. Defaults to the working directory when the pyocd tool was executed.
reset_type	str	'sw'	Which type of reset to use by default (one of 'default', 'hw', 'sw', 'sw_sysresetreq', 'sw_vectreset', 'sw_emulated').
reset.hold_time	float	0.1	Number of seconds to hold hardware reset asserted.
reset.post_delay	float	0.1	Number of seconds to delay after a reset is issued.
reset.halt_timeout	float	2.0	Timeout for waiting for the core to halt after a reset and halt.
resume_on_disconnect	bool	True	Whether to resume a halted target when disconnecting.
scan_all_aps	bool	False	Controls whether all 256 ADIv5 AP addresses will be probed.
serve_local_only	bool	True	When this option is True, the GDB server, probe server, semihosting telnet, and raw SWV server are only served on localhost, making them inaccessible across the network. Set to False to enable connecting to these ports from any machine on the network.
smart_flash	bool	True	If set to True, the flash loader will attempt to not program pages whose contents are not going to change by scanning target flash memory. A value of False will force all pages to be erased and programmed.
target_override	str	No default	Target type name to use instead of default board target or default cortex_m.
test_binary	str	No default	Specify the test binary file name used by the functional test suite (in the test/ directory). The binary must be in the binaries/ directory. This option is most useful when set in a board config file for running the functional tests on boards that cannot be automatically detected.
user_script	str	No default	Path of the user script file.
warning.cortex_m_default	bool	True	Whether to show the warning when no target type is selected and the default cortex_m target type is used. The warning is never shown if the cortex_m target type is explicitly specified.

GDB server options

These session options are currently only applied when running the GDB server.

Option Name	Type	Default	Description
enable_semihosting	bool	False	Set to True to handle semihosting requests. Also see the semihost_console_type option.
enable_swv	bool	False	Whether to enable SWV printf output over the semihosting console. Requires the swv_system_clock option to be set. The SWO baud rate can be controlled with the swv_clock option.
gdbserver_port	int	3333	Base TCP port for the gdbserver. The core number, which is 0 for the primary core, will be added to this value.
persist	bool	False	If True, the GDB server will not exit after GDB disconnects.
report_core_number	bool	False	Whether gdb server should report core number as part of the per-thread information.
rtos.enable	bool	True	Overall enable flag for RTOS aware debugging. By default it's enabled but can be switched off if necessary.
rtos.name	str	No default	Name of the RTOS plugin to use. If not set, all RTOS plugins are given a chance to load.
semihost_console_type	str	'telnet'	If set to 'telnet' then the semihosting telnet server will be started. If set to 'console' then semihosting will print to the console.
semihost_use_syscalls	bool	False	Whether to use GDB syscalls for semihosting file access operations, or to have pyOCD perform the operations. This is most useful if GDB is running on a remote system.
step_into_interrupt	bool	False	Set this option to True to enable interrupts when performing step operations. Otherwise interrupts will be disabled and step operations cannot be interrupted.
swv_clock	int	1000000 (1 MHz)	Frequency in Hertz of the SWO baud rate.
swv_system_clock	int	No default	Frequency in Hertz of the target's system clock. Used to compute the SWO baud rate divider.
swv_raw_enable	bool	True	Enable flag for the raw SWV stream server.
swv_raw_port	int	3443	TCP port number for the raw SWV stream server.
telnet_port	int	4444	Base TCP port number for the semihosting telnet server. The core number, which will be 0 for the primary core, is added to this value.
vector_catch	str	'h'	Enable vector catch sources, one letter per enabled source in any order, or all or none. The source letters are: h=hard fault b=bus fault m=mem fault e=secure fault i=irq err s=state err c=check err p=nocp r=reset a=all n=none
xpsr_control_fields	bool	False	When set to True, XPSR and CONTROL registers will have their respective bitfields defined for presentation in gdb.

J-Link probe options

These session options are available when the SEGGER J-Link debug probe plugin is active.

Option Name	Type	Default	Description
jlink.power	bool	True	Enable target power when connecting via a JLink probe, and disable power when disconnecting. Default is True.
jlink.device	str	No default	Set the device name passed to the J-Link. Normally, it doesn't matter because pyOCD does has its own device support, and so when this option is unset, "Cortex-M4" is used just to supply something valid. (For non-M4-based devices, you might see a warning about unexpected core type if you look at the J-Link logs, but this is harmless. J-Link does not support a "none" or "unknown" device type.)

Picoprobe options

These session options are available when the Picoprobe debug probe plugin is active.

Option Name	Type	Default	Description
picoprobe.safeswd	bool	False	Use safer but slower SWD transfer function with Picoprobe. Default is False, so possible WAIT or FAULT SWD acknowldeges and protocol errors will not be caught immediately.