CHiPs

December 2023/2024 Guide To Pico Debug Probe With Ubuntu 22.04/24.04

As of 2024-12, I am now using Ubuntu 24.04, and updated this document accordingly, these instructions may not work on Ubuntu 22.04 anymore.

Prerequisites

• A Raspberry Pi Pico Debug Probe, cf. https://www.raspberrypi.com/products/debug-probe/
• An Ubuntu 24.04 64 bits machine (x86-64 in my case)

Firmware setup

The Raspberry Pi Pico Debug Probe uses the debugprobe.uf2 UF2 file.

Grab it from https://github.com/raspberrypi/picoprobe/releases.

Install it on the probe in bootsel mode:

• Unplug probe from USB
• Open probe lid
• Press Bootsel button
• Plug probe back to USB
• Wait for RPI-PI2 mount point to appear
• Release Bootsel button
• Drag debugprobe.uf2 to RPI-PI2
• Close probe lid

Please note tht:

• picoprobe.uf2 debugprobe_on_pico.uf2 debugprobe_on_pico2.uf2 are intended for when you use a “real” Pico or Pico 2
• AFAIK, Pico W and Pico 2 W are not compatible

Software installation

OpenOCD

This assumes you have already installed a C compiling toolchain, this should be a good start:

sudo apt install build-essential autoconf automake libtool pkg-config

NB: Ubuntu 24.04 has an openocd 0.12 package, and it seems Pico Debug Probe support is included:

$ dpkg -L openocd | egrep "rp2040|rp2350|pico|cmsis-dap"
/usr/share/openocd/scripts/board/pico-debug.cfg
/usr/share/openocd/scripts/interface/cmsis-dap.cfg
/usr/share/openocd/scripts/target/rp2040-core0.cfg
/usr/share/openocd/scripts/target/rp2040.cfg

Perhaps there sould be support for RP3250, too…

[Obsolete?] However, it seems CMSIS-DAP support needs you to build Raspberry Pi’s version of OpenOCD:

cd ~/src
git clone https://github.com/raspberrypi/openocd
cd openocd
# Should be the defaut one
git checkout rp2040-v0.12.0
./bootstrap
./configure --enable-picoprobe
make -j($nproc)
sudo make install

Make sure your user is part of dialout and plugdev groups, or only root will be able to launch OpenOCD.

sudo cp -pv ./contrib/60-openocd.rules /etc/udev/rules.d
sudo systemctl restart udev

Other tools

We need multi-architecture versions of binutils and gdb:

sudo apt install binutils-multiarch gdb-multiarch

Even with this installed, scripts try to launch nm-multiarch and objdump-multiarch, so we need to have symbolic links to them:

sudo ln -s /usr/bin/nm /usr/local/bin/nm-multiarch
sudo ln -s /usr/bin/objdump /usr/local/bin/objdump-multiarch

VS Code

For my example project for HAGL’s Pico VGA board (https://github.com/CHiPs44/hagl_pico_vgaboard_example), a working .vscode/launch.json is:

{
  "version": "0.2.0",
  "configurations": [
    {
      "cwd": "${workspaceRoot}",
      "executable": "./example/build/hagl_pico_vgaboard_example.elf",
      "name": "Debug example with OpenOCD",
      "request": "launch",
      "type": "cortex-debug",
      "servertype": "openocd",
      "gdbPath": "gdb-multiarch",
      "configFiles": ["interface/cmsis-dap.cfg", "target/rp2040.cfg"],
      "searchDir": ["/usr/share/openocd/scripts/"],
      "showDevDebugOutput": "raw",
      "openOCDLaunchCommands": ["adapter speed 5000"],
      "svdFile": "${env:PICO_SDK_PATH}/src/rp2040/hardware_regs/rp2040.svd",
      "runToEntryPoint": "main",
      "postRestartCommands": ["break main", "continue"],
      "liveWatch": {
        "enabled": true,
        "samplesPerSecond": 4
      }
    }
  ]
}

Parameter executable must be changed to path of the ELF file for your project in the build directory.

For svdFile, you must have a clone of Pico SDK, and PICO_SDK_PATH environment variable must point to it, but it’s rather standard Pico stuff.

VS Code extensions

It seems that installing Cortex-Debug extension from marus25 is now sufficient to launch debugging with F5.

There is now an official Raspberry Pi Pico extension (https://github.com/raspberrypi/pico-vscode) which helps to setup simple projects, downloads up to date compilers, but does not yet handle seting project’s name via a variable, for example.

EOF

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