Skip to main content

Configuring Your Paragon PCB with Vial


  • Install QMK Toolbox to flash the PCB.
  • USB C cable to connect the PCB to your device.

Flashing the PCB

  1. Download the appropriate hex file for your PCB. Make sure the file extension remains as .hex.

  2. Open QMK Toolbox.

  3. Set the PCB into DFU mode. Note: the PCB must be connected to your device to be set into DFU mode.

    • DFU mode can be enabled through the following methods:

      1. Press the RESET button, located on the back of the PCB near the JST connector.
      2. If you already built your PCB, hold down both SHIFT keys (left and right) and press B.
        • Note: We do NOT recommend building your PCB without testing it first.
    • QMK Toolbox will tell you if the PCB is in DFU mode with the following message:

      Atmel DFU device connected: ATMEL ATm32U4DFU (03EB:2FF4:0000)
  4. In QMK Toolbox, click Open and load the downloaded hex file for your PCB.

  5. Click Flash. A successful flash will provide the following message:

    Attempting to flash, please don't remove device
    > dfu-programmer atmega32u4 erase --force
    > Erasing flash... Success
    > Checking memory from 0x0 to 0x6FFF... Empty
    > dfu-programmer atmega32u4 flash --force /Users/<your_user>/Downloads/paragon_<PCB_type>_vial.hex
    > 0% 100% Programming 0x5A80 bytes...
    > [>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>] Success
    > 0% 100% Reading 0x7000 bytes...
    > [>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>] Success
    > Validating... Success
    > 0x5A80 bytes written into 0x7000 bytes memory (80.80%)
    > dfu-programmer atmega32u4 reset
    Flash complete
    Atmel DFU device disconnected: ATMEL ATm32U4DFU (03EB:2FF4:0000)

Configuring your PCB through Vial

  1. Head over to with your PCB connected to your device.

  2. Click on Start Vial. A list of connected devices should pop up.

  3. Select Paragon from the device pop-up. At this point, the Vial UI should show up and display the layout schematic.

Configuring the Encoder

  1. To configure the behavior of the encoder in Vial, click on either of the two encoder buttons shown in the layout schematic.

  2. The left-side encoder shows an icon of turning the encoder counterclockwise. The right-side encoder shows an icon of turning the encoder clockwise.

  3. Clicking on either encoder button will allow you to map another function to it from the provided set.

Common Issues

  • My left Alt key isn't working.

    • Make sure you flashed the PCB with the correct hex file and loaded the JSON in VIA to configure the layout.
  • I received the following error when flashing my PCB:

    erasing flash success.
    checking memory 0x0 to 0x6fff empty.
    error reading line 1.
    atmega32u4 reset
    flash complete
    • Make sure to download the hex file correctly and save it with the .hex extension.