V-USB – A Firmware-Only USB Driver for Atmel AVR Microcontrollers

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V-USB – A Firmware-Only USB Driver for Atmel AVR Microcontrollers

V-USB is a software-only implementation of a low-speed USB device for Atmel’s AVR® microcontrollers, making it possible to build USB hardware with almost any AVR® microcontroller, not requiring any additional chip.

Thanks Travis!

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  1. Any chance that we might see this driver ported to the Arduino?

  2. @adafruit – Let me know once you’ve tried it out. I’m curious about how well it works.

    @ julienj – Doesn’t the Arduino have an FTDI TTL-RS232 to USB chip? That kind of negates the purpose of this driver.

  3. I’m surprised you weren’t aware of this project, ladyada! It’s been around for a while.

    I wouldn’t expect it to be ported to the Arduino, it requires a lot of timing sensitive hacks (quite a bit of assembler if I recall correctly), it would be EXTREMELY difficult to do it without the timing control provided by AVR-GCC.

    No reason you can’t use Arduino hardware with it, but you’ll need to develop with AVR-GCC. Not all arduino hardware has the FTDI chip, and for hardware with “bare” UART ports, one may wish to use USB for computer communications and have the UART available for communication with something else.

    I believe at least one of the projects is USB in, DMX out – pretty much not possible to do that with single-UART AVRs if you use the USB-to-serial-to-UART solution for PC comms.

  4. It’s actually fairly simple to get running. I managed to get it running with an ATtiny85 on a breadboard (and a USBtinyISP) in about half an hour. The final result ended up in a couple of little telepresence robots [1]. It tends to be a little picky about USB hubs, and it isn’t quite as stable as a hardware solution.

    I’ve just made up a metaboard clone, and I’m curious to see if I can get some manner of USB communication working through the arduino environment.

    [1] http://www.tony.thompson.name/2010/01/little-robots-hardware/
    [2] http://metalab.at/wiki/Metaboard

  5. If my memory serves me right, V-USB is available for 16MHz as well as 12MHz so it should be portable fairly easily.

    There are many more uses for USB than serial communication – keyboards and mice for example

  6. Entropy, we reviewed this for possible use with our AVR programmer, but went with the USBtiny core instead. Think of it as update to the project which used to be called “AVRUSB” or something.

    We use usb bitbang drivers in the usbtinyisp. They work ‘OK’, V-USB is more flexible, but had a really bizarre license for a while that scared us off from using it. I think that its been changed now.

  7. It’s GPL now — with commercial licenses available.

    Some of the commercial licenses come with dedicated VID/PID pairs.

  8. Oh, and there are some clock speeds that do not require crystal accuracy on AVRs with built in PLL support. For example, it’ll run fine on an ATtiny45/85 with the internal oscillator.

  9. It’s actually not an update of AVR-USB, it’s just a rename due to Atmel lawyers. 🙂

    (I’ve been following it on a semi-regular basis for a while. It became much more feasible when they added support for AVRs clocked at 16 MHz.)

  10. I read this post via the twitter feed. It was interesting to see both sides of the what will be an ongoing story.

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