# Build instructions for Embedded (ARM port)

First clone, initialize submodules and install Pipenv as defined [here](index.md).

## Requirements

You will need the GCC ARM toolchain for building and OpenOCD for flashing to a device.
You will also need Python dependencies for signing.

### Debian/Ubuntu

```sh
sudo apt-get install scons gcc-arm-none-eabi libnewlib-arm-none-eabi
```

### OS X

1. Download [gcc-arm-none-eabi](https://developer.arm.com/open-source/gnu-toolchain/gnu-rm/downloads)
2. Follow the [install instructions](https://launchpadlibrarian.net/287100883/readme.txt)
3. To install OpenOCD, run `brew install open-ocd`
4. Run `pipenv run make vendor build_boardloader build_bootloader build_firmware`

## Building

```sh
pipenv run make vendor build_boardloader build_bootloader build_firmware
```

## Uploading

Use `make upload` to upload the firmware to a production device. Do not forget to [enter bootloader](https://wiki.trezor.io/User_manual-Updating_the_Trezor_device_firmware__TT) on the device beforehand.

## Flashing

For flashing firmware to blank device (without bootloader) use `make flash`,
or `make flash STLINK_VER=v2-1` if using a ST-LINK/V2.1 interface.
You need to have OpenOCD installed.

## Building in debug mode

You can also build firmware in debug mode to see log output or run tests.

```sh
PYOPT=0 pipenv run make build_firmware
```

You can then use `screen` to enter the device's console. Do not forget to add your user to the `dialout` group or use `sudo`. Note that both the group and the tty name can differ, use `ls -l` to find out proper names on your machine.

```sh
screen /dev/ttyACM0
```

Debug console via serial port is enabled only for the Bitcoin-only firmware.
If you need the console to debug non-Bitcoin features, please edit `src/usb.py`,
disable WebAuthn USB interface and enable the VCP USB interface.
