# hf2

Implements [Microsofts HID Flashing Format (HF2)](https://github.com/microsoft/uf2/blob/86e101e3a282553756161fe12206c7a609975e70/hf2.md) to upload firmware to UF2 bootloaders. UF2 is factory programmed extensively by [Microsoft MakeCode](https://www.microsoft.com/en-us/makecode) and [Adafruit](https://www.adafruit.com) hardware.

Unless you know otherwise, you probably want [cargo-hf2](https://github.com/jacobrosenthal/hf2-rs)

## prerequisites

By default enables the hidapi feature and utilizes the [hidapi-sys crate](https://crates.io/crates/hidapi) which uses [libusb](https://github.com/libusb/hidapi). Presumably other transports could be added in the future that implement the ReadWrite trait internally.

### linux

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

```bash
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

```bash
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

```bash
sudo udevadm control --reload-rules
sudo udevadm trigger
```

### mac

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

## install

`cargo install cargo-hf2`

## use

Assuming using default feature hidapi and sloppily just grabbing the first device

```rust
let api = HidApi::new().expect("Couldn't find system usb");
let dev = api.device_list().nth(0).unwrap().open_device(&api).unwrap();
let chk = hf2::checksum_pages(&dev, 0x4000, 1).unwrap();
dbg!(chk.checksums);
```

## troubleshooting

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

```bash
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

```bash
RUST_LOG=debug cargo run
```