ST Link (st util) Specific Configuration

{
    "version": "0.2.0",
    "configurations": [
        {
            "type": "cortex-debug",
            "request": "launch",
            "servertype": "stutil",
            "cwd": "${workspaceRoot}",
            "executable": "./firmware.elf",
            "name": "Debug (ST-Util)",
            "device": "STM32F103RB",
            "v1": false
        }
    ]
}

v1

If you are using an older ST-Link V2 (for example the ST-Link that is embedded in the STM32 Value Line Discovery board), you need to specify "v1": true in the launch configuration.