USB Mass Storage - ZuluSCSI/ZuluSCSI-firmware GitHub Wiki

USB Mass Storage for ZuluSCSI

Theory of operation

  1. Set EnableUSBMassStorage=1 in the [SCSI] section of zuluscsi.ini
  2. Connect ZuluSCSI to a computer with a USB cable. The device ZuluSCSI is installed in must be powered off!
  3. ZuluSCSI LED should turn on solid and begin blinking. It is now in Mass Storage mode.
  4. A drive corresponding to your SD card will show up in finder/explorer/etc.
  5. Perform any changes you wish.
  6. Eject the drive/drag it to trash to eject.
  7. ZuluSCSI LED should go out, and ZuluSCSI resumes normal operation.

The USB cable can now be unplugged (or it may be left plugged in to access Serial console), and the device attached to ZuluSCSI may be powered on.

If a USB cable is not attached to a PC at power on, ZuluSCSI will function normally. In other words, ZuluSCSI's behavior will change only when the USB cable is connected to a PC when the ZuluSCSI is not otherwise powered, whereupon it will enter Mass Storage Mode.

Important notes

  • ZuluSCSI start-up will be delayed up to a second with Mass Storage enabled.
  • If ZuluSCSI has entered Mass Storage mode, ZuluSCSI will not act as a SCSI emulator. This is expected behavior: don't turn on the device ZuluSCSI is installed in while using MSC mode as it will not see any Zulu disks.
  • Fast blinking represents reads, slow blinking represents writes. Transfer speeds will max out at USB 1.1 speeds of around 1MB/second. It may take 10-15 seconds for the SD card to become accessible on the PC during which the LED will be blinking: This is normal.
  • If the LED goes out instead of going solid or rapidly blinking when plugged into a PC, ZuluSCSI did not enter mass storage mode. Try again by unplugging USB from ZuluSCSI and plugging it back in; this can occur if the computer is slow to scan the USB device.
  • Do not allow the computer to go to sleep while a transfer is in progress. ZuluSCSI may eject itself if the computer goes to sleep.
  • Once mass storage mode has been exited, or if it was never entered, it is not possible to enter mass storage mode again until the ZuluSCSI has been powered off.
  • A SD card must be installed in the ZuluSCSI to use mass storage mode. It will not enter mass storage mode otherwise.
  • It is not currently possible to "live edit" the SD card's contents while still functioning as a SCSI emulator, due to a high probability of corrupting filesystem(s).