August 1, 2011 AT 2:55 pm

The Isostick – Optical drive in a usb stick

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This is an interesting native-USB hack. An atmel (1287?) with a microsd slot that ‘looks’ like an optical disk drive to allow booting. We think someone could probably hack this together using an our Atmega32u4 breakout board or Teensy, MicroSD breakout board, and a heavy dose of LUFA.


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6 Comments

  1. I use grub4dos to boot ISO images
    from standard USB sticks.
    It works surprisingly well.
    Why should I use this pice of dedicated hardware?
    – lolli32

  2. …and beyond booting,
    I mount iso images on linux
    and windows systems to read them.
    Again there is no need for dedicated hardware.
    However, I would like to have a hardware
    emulating floppy disks on a shugart bus.
    – lolli32

  3. I really hope it’s not an at90usb1286 or equivalent, because the datarate on the device would *suck*. Those are only full-speed (12Mbps), and SD card access would have to be done with the SPI, which can only do 8Mbps…

    I suspect it’s more like a AT91SAM3U, which would have both high-speed USB and a hardware SDIO interface. That would actually be able to sustain a decent amount of bandwidth, as long as the SDHC protocol is implemented properly.

  4. It’s great to see one of these developed solely for cd drive emulation… now if only there was a section of read/write standard flash drive… oh wait wasn’t that the U3 drive? U3 drives were a complete pain to flash the cd drive portion, and they kinda died out.

    Hopefully isostick will catch on.

  5. Omega, it is an Atmel AVR32 with High-Speed (480Mbit/s) USB and hardware SD/MMC controller. The SD bus clock on the AVR32 has a maximum of 33MHz (half the max CPU rate of 66MHz). I evaluated the SAM3U soon after it went into production (I already had working AVR32 code), but found that most microSD cards do not perform fast enough to justify the move.

    The isostick gets 12.5MByte/s sustained from both the flash and optical drives, and the write speed depends on the microSD card used. We will be using Class 6 or Class 10 cards.

    See my blog for lots of technical details on isostick: http://blog.elegantinvention.com

    Thanks,
    Eric Agan

  6. Alistair Withworth

    People in China have been hacking Kingston USB keys to mount filesystem images for years. Too bad there’s so little documentation in English, I had to find out how to do it from an exchange student.

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