hf2-cli 0.2.2

CLI for Microsoft HID Flashing Library for UF2 Bootloaders
hf2-cli-0.2.2 is not a library.


Command line implementation of the hf2 flashing over hid protocol commonly used in by Microsoft MakeCode and Adafruit hardware.

Unless you know otherwise, you probably want cargo-hf2


Utilizes the hidapi-sys crate which uses libusb.


Youll need libusb depending on your distro you might do sudo apt-get install libudev-dev libusb-1.0-0-dev.

If you'd like to not use sudo, you'll need udev rules. With your board plugged in and in bootloader mode, use lsusb to find your vendorid, seen here as 239a

Bus 001 Device 087: ID 239a:001b Adafruit Industries Feather M0

Then put your vendorid below and save to something like /etc/udev/rules.d/99-adafruit-boards.rules

ATTRS{idVendor}=="239a", ENV{ID_MM_DEVICE_IGNORE}="1"
SUBSYSTEM=="usb", ATTRS{idVendor}=="239a", MODE="0666"
SUBSYSTEM=="tty", ATTRS{idVendor}=="239a", MODE="0666"

Then reboot or run

sudo udevadm control --reload-rules
sudo udevadm trigger


On mac, as of Catalina you will get a permissions prompt and must follow directions to allow "Input Monitoring" for the Terminal application.


cargo install hf2-cli


$ hf2
hf2 0.1.0
Microsoft HID Flashing Format


    -h, --help       Prints help information
    -V, --version    Prints version information

    -p <pid>
    -v <vid>

    bininfo                  This command states the current mode of the device
    dmesg                    Return internal log buffer if any. The result is a character array.
    flash                    flash
    help                     Prints this message or the help of the given subcommand(s)
    info                     Various device information. The result is a character array. See INFO_UF2.TXT in UF2
                             format for details.
    reset-into-app           Reset the device into user-space app.
    reset-into-bootloader    Reset the device into bootloader, usually for flashing
    verify                   verify

It will attempt to autodetect a device by sending the bininfo command any whitelisted devices it finds and using the first one that responds or you can specify pid and vid (before the subcommand) instead.

hf2 deals in binaries, not elf files so you're going to have to get a bin with something like cargo objcopy --example ferris_img --release -- -O binary ferris_img.bin Then you need your bootloaders address offset.

hf2 -v 0x239a -p 0x003d flash -f neopixel_rainbow.bin -a 0x4000


If it cant find a device, make sure your device is in a bootloader mode ready to receive firmware.

thread 'main' panicked at 'Are you sure device is plugged in and in bootloader mode?: OpenHidDeviceError', src/libcore/result.rs:1165:5
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace.

On the PyGamer, 2 button presses enables a blue and green screen that says PyGamer and also generally creates a flash drive which you should be able to see (though this doesn't use that method).

If you find another error, be sure to run with debug to see where in the process it failed and include those logs when reporting

RUST_LOG=debug hf2 -v 0x239a -p 0x003d flash -f neopixel_rainbow.bin -a 0x4000