TockOS Support Tool

pip, python-3, tock
pip install tock-loader==0.1.0



Tool for programming Tock onto hardware boards.


pip3 install tockloader --user

If you want tab completions:

register-python-argcomplete tockloader >> ~/.bashrc


This tool installs a binary called tockloader, which supports several commands.

Primary Commands

These are the main commands for managing apps on a board.

tockloader install

Load Tock applications on to the board. Use --no-replace to install multiple copies of the same app.

tockloader update

Update an application that is already flashed to the board with a new binary.

tockloader uninstall [application name(s)]

Remove an application from flash by its name.

Board Inspection Commands

These query the board for its current state.

tockloader list

Print information about the apps currently loaded onto the board.

tockloader info

Show all properties of the board.

Utility Commands

These provide other helpful features.

tockloader listen

Listen to UART printf() data from a board. Use the option --rtt to use Segger's RTT listener instead of using a serial port.

Other Commands

These provide more internal functionality.

tockloader flash

Load binaries onto hardware platforms that are running a compatible bootloader. This is used by the TockOS Make system when kernel binaries are programmed to the board with make program.

tockloader inspect-tab

Show details about a compiled TAB file.

tockloader enable-app [application name(s)]

Enable an app so that the kernel will run it at boot.

tockloader disable-app [application name(s)]

Disable an app so that the kernel will not start it at boot.

tockloader sticky-app [application name(s)]

Mark an app as sticky so that the --force flag is required to uninstall it.

tockloader unsticky-app [application name(s)]

Remove the sticky flag from an app.

tockloader list-attributes

Show all of the attributes that are stored on the board.

tockloader set-attribute [attribute key] [attribute value]

Set a particular attribute key to the specified value. This will overwrite an existing attribute if the key matches.

tockloader remove-attribute [attribute key]

Remove a particular attribute from the board.

tockloader dump-flash-page [page number]

Show the contents of a page of flash.

tockloader read [address] [# bytes]

Read arbitrary flash memory from the board.

tockloader list-known-boards

Print which boards tockloader has default settings for built-in.

Specifying the Board

For tockloader to know how to interface with a particular hardware board, it typically reads attributes from the bootloader to identify properties of the board. If those are unavailable, they can be specified as command line arguments.

tockloader [command] --arch [arch] --board [board]
  • arch: The architecture of the board. Likely cortex-m0 or cortex-m4.
  • board: The name of the board. This helps prevent incompatible applications from being flashed on the wrong board.

Tockloader also supports a JTAG interface using JLinkExe. JLinkExe requires knowing the device type of the MCU on the board.

tockloader [command] --jlink --arch [arch] --board [board] \
--jlink-cmd [jlink_cmd] --jlink-device [device] --jlink-speed [speed] --jlink-if [if]
  • jlink_cmd: The JLink executable to invoke. Defaults to JLinkExe on Mac/Linux, and JLink on Windows.
  • device: The JLinkExe device identifier.
  • speed: The speed value to pass to JLink. Defaults to 1200.
  • if: The interface to pass to JLink.

Tockloader can also do JTAG using OpenOCD. OpenOCD needs to know which config file to use. Note: you will likely need an up-to-date version of OpenOCD for everything to work. On MacOS you can use brew install --HEAD openocd to get a version from git.

tockloader [command] --openocd --arch [arch] --board [board] --openocd-board [openocd_board] \
--openocd-cmd [openocd_cmd] --openocd-options [openocd_options] \
--openocd-commands [openocd_commands]
  • openocd_board: The .cfg file in the board folder in OpenOCD to use.

  • openocd_cmd: The OpenOCD executable to invoke. Defaults to openocd.

  • openocd_options: A list of Tock-specific flags used to customize how Tockloader calls OpenOCD based on experience with various boards and their quirks. Options include:

    • noreset: Removes the command reset init; from OpenOCD commands.
    • nocmdprefix: Removes the commands init; reset init; halt; from OpenOCD commands.
    • workareazero: Adds the command set WORKAREASIZE 0; to OpenOCD commands.
    • resume: Adds the commands soft_reset_halt; resume; to OpenOCD commands.
  • openocd_commands: This sets a custom OpenOCD command string to allow Tockloader to program arbitrary chips with OpenOCD before support for the board is officially include in Tockloader. The following main operations can be customized:

    • program: Operation used to write a binary to the chip.
    • read: Operation used to read arbitrary flash memory on the chip.
    • erase: Operation that erases arbitrary ranges of flash memory on the chip.

    The custom values are specified as key=value pairs, for example, --openocd_commands 'program=write_image; halt;' 'erase=flash fillb {address:#x} 0xff 512;'. Operation strings can include wildcards which will get set with the correct value by Tockloader:

    • {{binary}}: The binary file path.
    • {address:#x}: The specified address for the binary to be programmed at.
    • {length}: The number of bytes. Only valid for the read operation.

Example Usage

Install an app, make sure it's up to date, and make sure it's the only app on the board:

tockloader install --make --erase

Get all info from the board that can be used to help debugging:

tockloader info

Print additionally debugging information. This can be helpful when using JTAG.

tockloader install --debug

Get printf() data from a board:

tockloader listen

Additional Flags

There are additional flags that might be useful for customizing tockloader's operation based on the requirements of a particular hardware platform.

  • --app-address: Manually specify the address at the beginning of where apps are stored. This can be in hex or decimal.
  • --bundle-apps: This forces tockloader to write all apps as a concatentated bundle using only a single flash command. This will require that anytime any app changes in any way (e.g. its header changes or the app is updated or a new app is installed.) all apps are re-written.


  • Supported communication protocols
    • Serial over USB
    • Segger JLinkExe JTAG support
    • OpenOCD JTAG support
  • JLink RTT listener

Complete Install Instructions

Tockloader is a Python script that is installed as an executable. To use Tockloader, you need python3, a couple dependencies, and the Tockloader package.

  • Ubuntu

    sudo apt install python3-pip
    pip3 install -U pip --user     # update pip
    pip3 install tockloader --user
  • MacOS

    brew install python3
    pip3 install tockloader
  • Windows

Internal Notes

Test Locally

To test the code locally without installing as a package, from the top-level directory:

python3 -m tockloader.main <COMMANDS>

Upload to PyPI

python3 sdist bdist_wheel
twine upload dist/*

Build Docs

pip3 install mkdocs
cd docs
cd ..
mkdocs serve --dev-addr=