R – USB drive LED flash

embeddedhardwareledusb

I was recently reading about the Arduino's Hello World application, and I thought to myself, "I wonder if I can do that with hardware that I have right now."

Since I don't have an Arduino, I grabbed a usb flash drive that I had laying around and started googling around for information about it. I didn't find much helpful information in this area, so I'm now asking here: is it possible for me to access a USB drive's hardware (e.g. the LED) and interact with it via some programming environment (I was thinking C# should probably have some way to do this)?

Also, related to this subject – does anyone know what kind of commands USB drives use? For example, SCSI storage devices have a standardized command set; ATA devices have a similar protocol. How are things like simple read/write commands issued to a USB storage device?

Best Answer

While the USB protocol is fairly generic, the peripheral devices are really function specific and require some kind of device driver on the host to function properly.

While a USB Flash Drive has a micro-controller on it, most USB storage devices follow a common protocol. That is why you don't have to install a different device driver for every drive you plug into windows.

I'm pretty sure that the mass storage protocol does not have a "Turn LED on" message :) And while the company that implemented the USB drive might actually have a special command to do that (maybe for debugging), I would doubt it would be published.

While I'm no guru on Windows, I believe that in order for you to access the USB stack directly, you would have to write your own device driver and plug load it in the kernel. Can you imagine if a regular application could send the "format everything" command to an arbitrary USB device.

Related Solutions

Delphi – How to get list of USB removable hard drives and memory sticks

{$MINENUMSIZE 4}
const
  IOCTL_STORAGE_QUERY_PROPERTY =  $002D1400;

type
  STORAGE_QUERY_TYPE = (PropertyStandardQuery = 0, PropertyExistsQuery, PropertyMaskQuery, PropertyQueryMaxDefined);
  TStorageQueryType = STORAGE_QUERY_TYPE;

  STORAGE_PROPERTY_ID = (StorageDeviceProperty = 0, StorageAdapterProperty);
  TStoragePropertyID = STORAGE_PROPERTY_ID;

  STORAGE_PROPERTY_QUERY = packed record
    PropertyId: STORAGE_PROPERTY_ID;
    QueryType: STORAGE_QUERY_TYPE;
    AdditionalParameters: array [0..9] of AnsiChar;
  end;
  TStoragePropertyQuery = STORAGE_PROPERTY_QUERY;

  STORAGE_BUS_TYPE = (BusTypeUnknown = 0, BusTypeScsi, BusTypeAtapi, BusTypeAta, BusType1394, BusTypeSsa, BusTypeFibre,
    BusTypeUsb, BusTypeRAID, BusTypeiScsi, BusTypeSas, BusTypeSata, BusTypeMaxReserved = $7F);
  TStorageBusType = STORAGE_BUS_TYPE;

  STORAGE_DEVICE_DESCRIPTOR = packed record
    Version: DWORD;
    Size: DWORD;
    DeviceType: Byte;
    DeviceTypeModifier: Byte;
    RemovableMedia: Boolean;
    CommandQueueing: Boolean;
    VendorIdOffset: DWORD;
    ProductIdOffset: DWORD;
    ProductRevisionOffset: DWORD;
    SerialNumberOffset: DWORD;
    BusType: STORAGE_BUS_TYPE;
    RawPropertiesLength: DWORD;
    RawDeviceProperties: array [0..0] of AnsiChar;
  end;
  TStorageDeviceDescriptor = STORAGE_DEVICE_DESCRIPTOR;

function GetBusType(Drive: AnsiChar): TStorageBusType;
var
  H: THandle;
  Query: TStoragePropertyQuery;
  dwBytesReturned: DWORD;
  Buffer: array [0..1023] of Byte;
  sdd: TStorageDeviceDescriptor absolute Buffer;
  OldMode: UINT;
begin
  Result := BusTypeUnknown;

  OldMode := SetErrorMode(SEM_FAILCRITICALERRORS);
  try
    H := CreateFile(PChar(Format('\\.\%s:', [AnsiLowerCase(Drive)])), 0, FILE_SHARE_READ or FILE_SHARE_WRITE, nil,
      OPEN_EXISTING, 0, 0);
    if H <> INVALID_HANDLE_VALUE then
    begin
      try
        dwBytesReturned := 0;
        FillChar(Query, SizeOf(Query), 0);
        FillChar(Buffer, SizeOf(Buffer), 0);
        sdd.Size := SizeOf(Buffer);
        Query.PropertyId := StorageDeviceProperty;
        Query.QueryType := PropertyStandardQuery;
        if DeviceIoControl(H, IOCTL_STORAGE_QUERY_PROPERTY, @Query, SizeOf(Query), @Buffer, SizeOf(Buffer), dwBytesReturned, nil) then
          Result := sdd.BusType;
      finally
        CloseHandle(H);
      end;
    end;
  finally
    SetErrorMode(OldMode);
  end;
end;


procedure GetUsbDrives(List: TStrings);
var
  DriveBits: set of 0..25;
  I: Integer;
  Drive: AnsiChar;
begin
  List.BeginUpdate;
  try
    Cardinal(DriveBits) := GetLogicalDrives;

    for I := 0 to 25 do
      if I in DriveBits then
      begin
        Drive := Chr(Ord('a') + I);
        if GetBusType(Drive) = BusTypeUsb then
          List.Add(Drive);
      end;
  finally
    List.EndUpdate;
  end;
end;

Linux – Find which drive corresponds to which USB mass storage device in Linux

I'm not sure in which kernel version this was implemented, but the /sys/block/* entries are symlinks to the devices.

In other words, /sys/block/sdb symlinks to a different directory, and its name contains the USB device ID.

$ file /sys/block/sdb
/sys/block/sdb: symbolic link to `../devices/pci0000:00/0000:00:02.1/usb1/1-1/1-1.1/1-1.1:1.0/host31/target31:0:0/31:0:0:0/block/sdb'
                                                  USB version and port here---^^^^^

The 1-1.1 is the interesting part, denoting usb1-port 1.device 1. When plugged into a hub, another level is added: 1-2.3.1, denoting usb1-port 2.port 3.device 1.

Pseudocode:

get partition name # e.g. /dev/sdb1
get disk name # that would be /dev/sdb
get your basename # sdb
see where /sys/block/$your_basename points to # e.g. ../devices/blah/blah/1-2.1/blah
get the longest substring matching "\d-\d+(.\d+)*"  # e.g. 1-2.1
that is the device id you want
/sys/bus/usb/devices/$device_id/ has all kinds of information about it
the ID corresponds to hardware USB ports

Working example script in bash.

Best Answer

Related Solutions

Delphi – How to get list of USB removable hard drives and memory sticks

Linux – Find which drive corresponds to which USB mass storage device in Linux

Related Topic