The following information will focus on the software development.

board
=====

The BusVoodoo uses a [custom board](https://bus.cuvoodoo.info/manual/index.html#_hardware_development) based on a  [STM32F103RC](http://www.st.com/en/microcontrollers/stm32f103rc.html) micro-controller.

code
====

dependencies
------------

To develop the firmware, following Linux packages are required: 

- _arm-none-eabi-gcc_ to compile the source code
- _arm-none-eabi-binutils_ to create the firmware binaries
- _arm-none-eabi-gdb_ to debug the firmware
- _rake_ automate development steps
- _openocd_ to flash and debug over SWD (when using an ST-Link V2 adapter)
- _doxygen_ to compile the documentation

The source code uses the [libopencm3](http://libopencm3.org/) library.
The projects is already a git submodules.
It will be initialized when compiling the firmware.
Alternatively you can run once: `git submodule init` and `git submodule update`.

firmware
--------

To compile the firmware files run `rake`.
This will generate two firmware:

- _bootloader_: a USB DFU bootloader
- _application_: the main application

*IMPORTANT*: to build the firmware for BusVoodoo hardware version 0, prepend `BUSVOODOO_HARDWARE_VERSION=0` before every `rake` command. This will make sure the few pin assignment differences are taken into account in the firmware.

documentation
-------------

To generate doxygen documentation run `rake doc`.
The documentation describing all files, functions, and variables will be available in the _doc_ folder.

Further comments are in the source code.

flash
-----

There are two firmware images: `bootloader` and `application`.
The `bootloader` image allows to flash the `application` over USB using the DFU protocol.
The `bootloader` is started first and immediately jumps to the `application` if it is valid and the DFU mode is not forced.
The `application` image is the main application and is implemented in `application.c`.

The `bootloader` image will be flashed using SWD (Serial Wire Debug).
For that you need an SWD adapter.
The `Makefile` uses a Black Magic Probe (per default), or a ST-Link V2 along OpenOCD software.
To flash the `booltoader` using SWD run `rake flash_booloader`.

Once the `bootloader` is flashed it is possible to flash the `application` over USB using the DFU protocol by running `rake flash`.
The `application` advertises USB DFU support (along with the USB CDC ACM class).
If the application is broken, force the bootloader to start the DFU mode by shorting the contacts marked as DFU on the board while powering up.
It is also possible to flash the `application` image using SWD by running `rake flash_application`.

debug
-----

SWD also allows to debug the code running on the micro-controller using GDB.
To start the debugging session run `rake debug`.

USB
---

The firmware offers serial communication over USART 1 and USB (using the CDC ACM device class).