RP2040 Auto Flash

Auto-flash your Raspberry Pi Pico / RP2040 UF2 files from VS Code without pressing BOOTSEL — exactly like Arduino IDE does.

How It Works

This extension replicates the 1200bps DTR magic trick used by the Arduino-Pico core (uf2conv.py):

1. Opens your RP2040's serial COM port at 9600 baud
2. Asserts DTR (Data Terminal Ready)
3. Waits ~100ms
4. Clears DTR
5. Switches to 1200 baud and closes the port
6. The RP2040 firmware detects this sequence and reboots into USB bootloader mode
7. Extension waits for the RPI-RP2 USB drive to appear
8. Copies your .uf2 file to the drive → RP2040 flashes itself and reboots ✅

⚠️ This trick requires that your RP2040 firmware exposes a USB CDC serial interface. If your firmware has no USB serial, the board must be reset manually the first time (hold BOOTSEL while plugging in), then flash via this extension — from that point on auto-reset works as long as your firmware includes USB serial.

Installation

From VSIX (manual install)

# 1. Clone / download this extension folder
# 2. Install dependencies
npm install

# 3. Package it
npm run package
# → produces rp2040-autoflash-1.0.3.vsix

# 4. Install in VS Code
code --install-extension rp2040-autoflash-1.0.3.vsix

From VS Code

Ctrl+Shift+P → Extensions: Install from VSIX… → select the .vsix file.

Commands

Open the Command Palette (Ctrl+Shift+P) and search for RP2040:

Right-click shortcut

Right-click any .uf2 file in the Explorer sidebar → RP2040: Auto Flash UF2

Settings

Open Settings (Ctrl+,) and search for rp2040:

workspace .vscode/settings.json example

{
  "rp2040-autoflash.serialPort": "/dev/ttyACM0",
  "rp2040-autoflash.uf2Path": "${workspaceFolder}/build/firmware.uf2",
  "rp2040-autoflash.bootloaderWaitMs": 3000
}

Supported Platforms

Linux: udev rule (avoid sudo)

Add this rule so VS Code can access serial ports without root:

echo 'SUBSYSTEM=="tty", ATTRS{idVendor}=="2e8a", MODE="0666"' | sudo tee /etc/udev/rules.d/99-rp2040.rules
sudo udevadm control --reload-rules && sudo udevadm trigger

Workflow with Pico SDK / CMake

# Build your firmware (CMake)
cd build && cmake .. && make -j4

# The extension will find build/firmware.uf2 automatically if you set uf2Path
# Or right-click firmware.uf2 in VS Code Explorer → RP2040: Auto Flash UF2

Combine with a VS Code Task (.vscode/tasks.json)

{
  "version": "2.0.0",
  "tasks": [
    {
      "label": "Build & Flash RP2040",
      "type": "shell",
      "command": "cd build && make -j4",
      "group": { "kind": "build", "isDefault": true },
      "presentation": { "reveal": "always" },
      "dependsOn": [],
      "postBuild": {
        "command": "rp2040-autoflash.flash"
      }
    }
  ]
}

Troubleshooting

"No serial ports found"

• Make sure your RP2040 firmware includes a USB CDC serial interface (stdio_usb_init() in C SDK, or import usb_cdc in CircuitPython).
• On Linux, add your user to the dialout group: sudo usermod -aG dialout $USER then log out/in.

"Could not find RPI-RP2 drive"

• Increase bootloaderWaitMs to 5000 or more.
• On Windows, check Device Manager — the drive should appear as a removable disk.
• Set drivePath manually if auto-detect fails.

Reset works but board stays in bootloader

• The UF2 file may be corrupt or built for a different board. Verify with picotool info firmware.uf2.