> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/vedderb/bldc/llms.txt
> Use this file to discover all available pages before exploring further.

# Flashing

> Upload compiled firmware to your VESC using a SWD debugger or VESC Tool over USB.

There are two methods to flash firmware onto a VESC: using a SWD hardware debugger, or uploading via VESC Tool over USB.

<CardGroup cols={2}>
  <Card title="Method 1: SWD debugger" icon="cpu">
    Requires STLink or compatible JTAG/SWD probe. Needed for first-time flashing and recovering a bricked device.
  </Card>

  <Card title="Method 2: VESC Tool USB" icon="usb">
    Upload a `.bin` file through the VESC Tool application. No extra hardware required once a bootloader is present.
  </Card>
</CardGroup>

## Method 1: SWD debugger

This method uses OpenOCD and a SWD/JTAG probe (such as an STLink v2) to write firmware directly to the device.

<Steps>
  <Step title="Flash the bootloader">
    Before flashing application firmware for the first time, you must flash the bootloader. Clone and build the [bldc-bootloader](https://github.com/vedderb/bldc-bootloader) project and follow its instructions.
  </Step>

  <Step title="Build your target firmware">
    Build the firmware for your board:

    ```bash theme={null}
    make 100_250
    ```
  </Step>

  <Step title="Flash the firmware">
    Use the `_flash` make target for your board. For the VESC 100/250:

    ```bash theme={null}
    make 100_250_flash
    ```

    This invokes OpenOCD to write the compiled `.elf` to the device over SWD.
  </Step>
</Steps>

<Note>
  On Linux, you can use the STLink v2 programmer without root access by installing the udev rules. See [Prerequisites](/building/prerequisites) for the commands.
</Note>

## Method 2: VESC Tool USB upload

This method uploads a compiled `.bin` file through the VESC Tool application over USB. A working bootloader must already be present on the device.

<Warning>
  Do not disconnect power or USB from the VESC during the upload process. Doing so risks bricking the device.
</Warning>

<Steps>
  <Step title="Build the firmware">
    Build the `.bin` file for your board:

    ```bash theme={null}
    make 100_250
    ```

    The output file is located at `build/100_250/100_250.bin`.
  </Step>

  <Step title="Connect to the VESC in VESC Tool">
    Open VESC Tool and connect to your VESC over USB.
  </Step>

  <Step title="Navigate to the Firmware tab">
    Select the **Firmware** tab from the left side menu.
  </Step>

  <Step title="Select your firmware file">
    Click the **Custom file** tab, then click the folder icon to browse for and select your `.bin` file (e.g. `build/100_250/100_250.bin`).
  </Step>

  <Step title="Start the upload">
    Press the upload firmware button (downward arrow) in the bottom right to begin the upload.

    It is normal for VESC Tool to show a disconnect during the upload process.
  </Step>

  <Step title="Wait for completion">
    Wait for the loading bar to complete, then **wait an additional 10 seconds** before disconnecting anything.

    <Warning>
      Disconnecting power or USB before the 10-second wait completes after "FW Upload DONE" risks bricking your VESC.
    </Warning>
  </Step>

  <Step title="Reconnect">
    The VESC will disconnect itself once the new firmware is running. You can then reconnect in VESC Tool.
  </Step>
</Steps>

## If your VESC is bricked

A bricked VESC cannot accept USB firmware uploads because the bootloader is no longer functional. To recover:

1. Use a SWD debugger (Method 1 above) to re-flash valid firmware directly.
2. You must flash the [bootloader](https://github.com/vedderb/bldc-bootloader) first, then the application firmware.

<Note>
  A SWD debugger is the only way to recover a bricked VESC. Keep one available if you are frequently updating firmware.
</Note>