What is V-USB?

V-USB is a firmware-only USB driver for Atmel's AVR microcontrollers. For more information please visit http://www.obdev.at/vusb/.

What is in this Repository?

This repository contains the source code of the driver (in the usbdrv subdirectory), examples (in the examples) subdirectory and other things you might need when you design a device using V-USB.

When you check out this repository, the resulting directory is not equivalent to the source code package which can be downloaded at http://www.obdev.at/vusb/. Some files in the source code package are generated by scripts when the package is created. On the other hand, the scripts which generate source files and the package are not contained in the package itself.

If you want to know more about the files and directories, see the file Readme.txt in the top level directory.

How do I Add the Driver to My Project?

In a Makefile

Simply copy the entire usbdrv subdirectory into your project's firmware source code directory. Then edit the firmware's Makefile and add the following object files to your binary:

usbdrv/usbdrv.o
usbdrv/usbdrvasm.o
usbdrv/oddebug.o

Then make sure that your Makefile contains rules to convert *.S and *.c to object files. See the Makefiles in the examples subdirectory for an inspiration.

With PlatformIO

The easiest way to use V-USB in PlatformIO is to just copy the usbdrv folder to the src directory of the project:

project/
├── platformio.ini
└── src/
    ├── main.c
    ├── usbconfig.h
    └── usbdrv/
        ├── usbdrv.c
        ├── usbdrv.h
        ├── usbdrvasm.S
        ├── usbdrvasm*.inc
        ├── oddebug.c
        └── oddebug.h

The usbconfig.h is part of your project. Derive it from the template as usual.

In platformio.ini you must make sure that .S files are preprocessed by the "C" preprocessor and then passed to the assembler. .inc and .asmfiles should not be touched, they are included as needed.

Here is a minimal example platformio.ini for a bare metal ATTiny85:

[env:attiny85]
platform = atmelavr
board = attiny85

board_build.f_cpu = 16500000L      ; also reaches usbdrvasm.S as -DF_CPU=...

build_flags =
    -Isrc                          ; explicit, so usbdrv/*.c find usbconfig.h
    -Wall

; keep the IAR-syntax assembly file out of the build
build_src_filter =
    +<*>
    -<usbdrv/usbdrvasm.asm>