USB_desc giving me wrong/different number of interfaces (Line6 HX Stomp)...

[kempline]

... compared to pyusb

Here's the output of USB_desc

`
01

Device descriptor:
Descriptor Length: 12
Descriptor type: 01
USB version: 0200
Device class: EF
Device Subclass: 02
Device Protocol: 01
Max.packet size: 40
Vendor ID: 0E41
Product ID: 4246
Revision ID: 0200
Mfg.string index: 01
Prod.string index: 03
Serial number index: 02
Number of conf.: 01
total_length: 32

Configuration descriptor:
Total length: 0020
Num.intf: 01
Conf.value: 01
Conf.string: 00
Attr.: C0
Max.pwr: 00

Interface descriptor:
Intf.number: 00
Alt.: 00
Endpoints: 02
Intf. Class: FF
Intf. Subclass: 00
Intf. Protocol: 00
Intf.string: 00

Endpoint descriptor:
Endpoint address: 81
Attr.: 02
Max.pkt size: 0040
Polling interval: 00

Endpoint descriptor:
Endpoint address: 01
Attr.: 02
Max.pkt size: 0040
Polling interval: 00

Addr:1(0.0.1)
`

And here's the output of a python script basically dumping the current configuration:

DEVICE ID 0e41:4246 on Bus 000 Address 003 =================
bLength : 0x12 (18 bytes)
bDescriptorType : 0x1 Device
bcdUSB : 0x200 USB 2.0
bDeviceClass : 0xef Miscellaneous
bDeviceSubClass : 0x2
bDeviceProtocol : 0x1
bMaxPacketSize0 : 0x40 (64 bytes)
idVendor : 0x0e41
idProduct : 0x4246
bcdDevice : 0x200 Device 2.0
iManufacturer : 0x1 LINE 6
iProduct : 0x3 HX Stomp
iSerialNumber : 0x2 3090436
bNumConfigurations : 0x1
CONFIGURATION 1: 0 mA ====================================
bLength : 0x9 (9 bytes)
bDescriptorType : 0x2 Configuration
wTotalLength : 0x130 (304 bytes)
bNumInterfaces : 0x6
bConfigurationValue : 0x1
iConfiguration : 0x0
bmAttributes : 0xc0 Self Powered
bMaxPower : 0x0 (0 mA)
INTERFACE 0: Vendor Specific ===========================
bLength : 0x9 (9 bytes)
bDescriptorType : 0x4 Interface
bInterfaceNumber : 0x0
bAlternateSetting : 0x0
bNumEndpoints : 0x2
bInterfaceClass : 0xff Vendor Specific
bInterfaceSubClass : 0x0
bInterfaceProtocol : 0x0
iInterface : 0x0
ENDPOINT 0x81: Bulk IN ===============================
bLength : 0x7 (7 bytes)
bDescriptorType : 0x5 Endpoint
bEndpointAddress : 0x81 IN
bmAttributes : 0x2 Bulk
wMaxPacketSize : 0x200 (512 bytes)
bInterval : 0x0
ENDPOINT 0x1: Bulk OUT ===============================
bLength : 0x7 (7 bytes)
bDescriptorType : 0x5 Endpoint
bEndpointAddress : 0x1 OUT
bmAttributes : 0x2 Bulk
wMaxPacketSize : 0x200 (512 bytes)
bInterval : 0x0
INTERFACE 1: Audio =====================================
bLength : 0x9 (9 bytes)
bDescriptorType : 0x4 Interface
bInterfaceNumber : 0x1
bAlternateSetting : 0x0
bNumEndpoints : 0x0
bInterfaceClass : 0x1 Audio
bInterfaceSubClass : 0x1
bInterfaceProtocol : 0x20
iInterface : 0x0
INTERFACE 2: Audio =====================================
bLength : 0x9 (9 bytes)
bDescriptorType : 0x4 Interface
bInterfaceNumber : 0x2
bAlternateSetting : 0x0
bNumEndpoints : 0x0
bInterfaceClass : 0x1 Audio
bInterfaceSubClass : 0x2
bInterfaceProtocol : 0x20
iInterface : 0x0
INTERFACE 2, 1: Audio ==================================
bLength : 0x9 (9 bytes)
bDescriptorType : 0x4 Interface
bInterfaceNumber : 0x2
bAlternateSetting : 0x1
bNumEndpoints : 0x1
bInterfaceClass : 0x1 Audio
bInterfaceSubClass : 0x2
bInterfaceProtocol : 0x20
iInterface : 0x0
ENDPOINT 0x3: Isochronous OUT ========================
bLength : 0x7 (7 bytes)
bDescriptorType : 0x5 Endpoint
bEndpointAddress : 0x3 OUT
bmAttributes : 0x5 Isochronous
wMaxPacketSize : 0xe0 (224 bytes)
bInterval : 0x1
INTERFACE 3: Audio =====================================
bLength : 0x9 (9 bytes)
bDescriptorType : 0x4 Interface
bInterfaceNumber : 0x3
bAlternateSetting : 0x0
bNumEndpoints : 0x0
bInterfaceClass : 0x1 Audio
bInterfaceSubClass : 0x2
bInterfaceProtocol : 0x20
iInterface : 0x0
INTERFACE 3, 1: Audio ==================================
bLength : 0x9 (9 bytes)
bDescriptorType : 0x4 Interface
bInterfaceNumber : 0x3
bAlternateSetting : 0x1
bNumEndpoints : 0x1
bInterfaceClass : 0x1 Audio
bInterfaceSubClass : 0x2
bInterfaceProtocol : 0x20
iInterface : 0x0
ENDPOINT 0x83: Isochronous IN ========================
bLength : 0x7 (7 bytes)
bDescriptorType : 0x5 Endpoint
bEndpointAddress : 0x83 IN
bmAttributes : 0x25 Isochronous
wMaxPacketSize : 0xe0 (224 bytes)
bInterval : 0x1
INTERFACE 4: Audio =====================================
bLength : 0x9 (9 bytes)
bDescriptorType : 0x4 Interface
bInterfaceNumber : 0x4
bAlternateSetting : 0x0
bNumEndpoints : 0x2
bInterfaceClass : 0x1 Audio
bInterfaceSubClass : 0x3
bInterfaceProtocol : 0x0
iInterface : 0x0
ENDPOINT 0x2: Bulk OUT ===============================
bLength : 0x9 (7 bytes)
bDescriptorType : 0x5 Endpoint
bEndpointAddress : 0x2 OUT
bmAttributes : 0x2 Bulk
wMaxPacketSize : 0x200 (512 bytes)
bInterval : 0x0
ENDPOINT 0x82: Bulk IN ===============================
bLength : 0x9 (7 bytes)
bDescriptorType : 0x5 Endpoint
bEndpointAddress : 0x82 IN
bmAttributes : 0x2 Bulk
wMaxPacketSize : 0x200 (512 bytes)
bInterval : 0x0
INTERFACE 5: Human Interface Device ====================
bLength : 0x9 (9 bytes)
bDescriptorType : 0x4 Interface
bInterfaceNumber : 0x5
bAlternateSetting : 0x0
bNumEndpoints : 0x1
bInterfaceClass : 0x3 Human Interface Device
bInterfaceSubClass : 0x0
bInterfaceProtocol : 0x0
iInterface : 0x0
ENDPOINT 0x84: Interrupt IN ==========================
bLength : 0x7 (7 bytes)
bDescriptorType : 0x5 Endpoint
bEndpointAddress : 0x84 IN
bmAttributes : 0x3 Interrupt
wMaxPacketSize : 0x8 (8 bytes)
bInterval : 0x8

I'd like to use interface 4 for Midi communication but as far as I understand, USB_desc is only detecting one interface. Anything I can do/try?

Thanks in advance
kempline

[kempline]

Hello again,

I just realised USB_desc comes with the generic USB Host Shield Library so I opened an issue on their repro as wel.

If you don't mind we could leave this issue open. Otherwise feel free to close it if.

Thanks
kempline

[YuuichiAkagawa]

Have you tried USB_MIDI_desc?

/~https://github.com/YuuichiAkagawa/USBH_MIDI/blob/master/examples/USB_MIDI_desc/USB_MIDI_desc.ino

[kempline]

I was not aware of that example but is gives me pretty much the same output:

`
01

String Descriptors:
Manufacturer: LINE 6
Product: HX Stomp
Serial: 3090436

Device descriptor:
Descriptor Length: 12
Descriptor type: 01
USB version: 0200
Device class: EF
Device Subclass: 02
Device Protocol: 01
Max.packet size: 40
Vendor ID: 0E41
Product ID: 4246
Revision ID: 0200
Mfg.string index: 01
Prod.string index: 03
Serial number index: 02
Number of conf.: 01

Configuration descriptor:
Total length: 0020
Num.intf: 01
Conf.value: 01
Conf.string: 00
Attr.: C0
Max.pwr: 00

Interface descriptor:
Intf.number: 00
Alt.: 00
Endpoints: 02
Intf. Class: FF
Intf. Subclass: 00
Intf. Protocol: 00
Intf.string: 00

Endpoint descriptor:
Endpoint address: 81
Attr.: 02(Bulk)
Max.pkt size: 0040
Polling interval: 00

Endpoint descriptor:
Endpoint address: 01
Attr.: 02(Bulk)
Max.pkt size: 0040
Polling interval: 00

Addr:1(0.0.1)

`

[YuuichiAkagawa]

Does the LINE 6 HX Stomp support Full-Speed? USB Host Shield does not support High-Speed.

The contents of the configuration descriptor are different.

USB Host Shield

Configuration descriptor:
Total length: 0020
Num.intf: 01

pyusb(PC)

CONFIGURATION 1: 0 mA ====================================
wTotalLength : 0x130 (304 bytes)
bNumInterfaces : 0x6

[kempline]

Well, that's a very good question. At least it connects as High-Speed Midi device to my laptop. Do you have any idea how I can simulate lower USB speeds? Maybe I can try to find a USB 1.0 hub somewhere - would that be a good test?

[YuuichiAkagawa]

Maybe I can try to find a USB 1.0 hub somewhere - would that be a good test?

Yes. I also think it's good.

[kempline]

One of my colleagues found an old USB 1.0 hub and if I connect the LINE 6 HX Stomp thru this hub to my laptop the interface list (see my first posting) gets shortened as:

DEVICE ID 0e41:4246 on Bus 001 Address 008 =================
bLength : 0x12 (18 bytes)
bDescriptorType : 0x1 Device
bcdUSB : 0x200 USB 2.0
bDeviceClass : 0xef Miscellaneous
bDeviceSubClass : 0x2
bDeviceProtocol : 0x1
bMaxPacketSize0 : 0x40 (64 bytes)
idVendor : 0x0e41
idProduct : 0x4246
bcdDevice : 0x200 Device 2.0
iManufacturer : 0x1 LINE 6
iProduct : 0x3 HX Stomp
iSerialNumber : 0x2 3090436
bNumConfigurations : 0x1
CONFIGURATION 1: 0 mA ====================================
bLength : 0x9 (9 bytes)
bDescriptorType : 0x2 Configuration
wTotalLength : 0x20 (32 bytes)
bNumInterfaces : 0x1
bConfigurationValue : 0x1
iConfiguration : 0x0
bmAttributes : 0xc0 Self Powered
bMaxPower : 0x0 (0 mA)
INTERFACE 0: Vendor Specific ===========================
bLength : 0x9 (9 bytes)
bDescriptorType : 0x4 Interface
bInterfaceNumber : 0x0
bAlternateSetting : 0x0
bNumEndpoints : 0x2
bInterfaceClass : 0xff Vendor Specific
bInterfaceSubClass : 0x0
bInterfaceProtocol : 0x0
iInterface : 0x0
ENDPOINT 0x81: Bulk IN ===============================
bLength : 0x7 (7 bytes)
bDescriptorType : 0x5 Endpoint
bEndpointAddress : 0x81 IN
bmAttributes : 0x2 Bulk
wMaxPacketSize : 0x40 (64 bytes)
bInterval : 0x0
ENDPOINT 0x1: Bulk OUT ===============================
bLength : 0x7 (7 bytes)
bDescriptorType : 0x5 Endpoint
bEndpointAddress : 0x1 OUT
bmAttributes : 0x2 Bulk
wMaxPacketSize : 0x40 (64 bytes)
bInterval : 0x0

That's pretty much what I get when using the USB Host Shield Library. Thus, I can confirm that it is speed-dependent and that the USB Host Shield Library can't be used to have functionality with LINE 6's HX Stomp.

Thanks @YuuichiAkagawa for pointing me to the speed issue. Are you aware of any alternatives? Are there other solutions allowing for high-speed communication using main-stream microcontrollers?

Regards
kempline

[YuuichiAkagawa]

Thank you for your report.

Teensy 3.6 & 4.x has a high speed USB Host. But I haven't tried MIDI in high speed mode.

My AKAI MPC Studio 2 is also dedicated to high speed, so I tried Teensy 3.6.
It seems to work.

https://gist.github.com/YuuichiAkagawa/2b3a0cd99638b7c0823b939bbf8b3e18

$ lsusb -tv
/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/12p, 480M
    ID 1d6b:0002 Linux Foundation 2.0 root hub
    |__ Port 3: Dev 8, If 0, Class=Audio, Driver=snd-usb-audio, 480M
        ID 09e8:004a AKAI  Professional M.I. Corp. 

$ lsusb -v -d 09e8:004a

Bus 001 Device 008: ID 09e8:004a AKAI  Professional M.I. Corp. MPC Studio
Couldn't open device, some information will be missing
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               2.00
  bDeviceClass            0 
  bDeviceSubClass         0 
  bDeviceProtocol         0 
  bMaxPacketSize0        64
  idVendor           0x09e8 AKAI  Professional M.I. Corp.
  idProduct          0x004a 
  bcdDevice            0.00
  iManufacturer           1 
  iProduct                2 
  iSerial                 3 
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength       0x0078
    bNumInterfaces          2
    bConfigurationValue     1
    iConfiguration          0 
    bmAttributes         0x80
      (Bus Powered)
    MaxPower              500mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           0
      bInterfaceClass         1 Audio
      bInterfaceSubClass      1 Control Device
      bInterfaceProtocol      0 
      iInterface              2 
      AudioControl Interface Descriptor:
        bLength                 9
        bDescriptorType        36
        bDescriptorSubtype      1 (HEADER)
        bcdADC               1.00
        wTotalLength       0x0009
        bInCollection           1
        baInterfaceNr(0)        1
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       0
      bNumEndpoints           2
      bInterfaceClass         1 Audio
      bInterfaceSubClass      3 MIDI Streaming
      bInterfaceProtocol      0 
      iInterface              2 
      MIDIStreaming Interface Descriptor:
        bLength                 7
        bDescriptorType        36
        bDescriptorSubtype      1 (HEADER)
        bcdADC               1.00
        wTotalLength       0x0054
      MIDIStreaming Interface Descriptor:
        bLength                 6
        bDescriptorType        36
        bDescriptorSubtype      2 (MIDI_IN_JACK)
        bJackType               1 Embedded
        bJackID                 1
        iJack                   4 
      MIDIStreaming Interface Descriptor:
        bLength                 6
        bDescriptorType        36
        bDescriptorSubtype      2 (MIDI_IN_JACK)
        bJackType               1 Embedded
        bJackID                 2
        iJack                   5 
      MIDIStreaming Interface Descriptor:
        bLength                 6
        bDescriptorType        36
        bDescriptorSubtype      2 (MIDI_IN_JACK)
        bJackType               1 Embedded
        bJackID                 3
        iJack                   6 
      MIDIStreaming Interface Descriptor:
        bLength                 9
        bDescriptorType        36
        bDescriptorSubtype      3 (MIDI_OUT_JACK)
        bJackType               1 Embedded
        bJackID                 4
        bNrInputPins            1
        baSourceID( 0)          1
        BaSourcePin( 0)         1
        iJack                  20 
      MIDIStreaming Interface Descriptor:
        bLength                 9
        bDescriptorType        36
        bDescriptorSubtype      3 (MIDI_OUT_JACK)
        bJackType               1 Embedded
        bJackID                 5
        bNrInputPins            1
        baSourceID( 0)          2
        BaSourcePin( 0)         1
        iJack                  21 
      MIDIStreaming Interface Descriptor:
        bLength                 9
        bDescriptorType        36
        bDescriptorSubtype      3 (MIDI_OUT_JACK)
        bJackType               1 Embedded
        bJackID                 6
        bNrInputPins            1
        baSourceID( 0)          3
        BaSourcePin( 0)         1
        iJack                  22 
      Endpoint Descriptor:
        bLength                 9
        bDescriptorType         5
        bEndpointAddress     0x01  EP 1 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
        bRefresh                0
        bSynchAddress           0
        MIDIStreaming Endpoint Descriptor:
          bLength                 7
          bDescriptorType        37
          bDescriptorSubtype      1 (GENERAL)
          bNumEmbMIDIJack         3
          baAssocJackID( 0)       1
          baAssocJackID( 1)       2
          baAssocJackID( 2)       3
      Endpoint Descriptor:
        bLength                 9
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
        bRefresh                0
        bSynchAddress           0
        MIDIStreaming Endpoint Descriptor:
          bLength                 7
          bDescriptorType        37
          bDescriptorSubtype      1 (GENERAL)
          bNumEmbMIDIJack         3
          baAssocJackID( 0)       4
          baAssocJackID( 1)       5
          baAssocJackID( 2)       6

Via USB 1.1 Hub

$ lsusb -vt
/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/12p, 480M
    ID 1d6b:0002 Linux Foundation 2.0 root hub
    |__ Port 3: Dev 6, If 0, Class=Hub, Driver=hub/4p, 12M
        ID 03eb:0902 Atmel Corp. 4-Port Hub
        |__ Port 4: Dev 7, If 0, Class=Vendor Specific Class, Driver=, 12M
            ID 09e8:004a AKAI  Professional M.I. Corp. 

$ lsusb -v -d 09e8:004a

Bus 001 Device 007: ID 09e8:004a AKAI  Professional M.I. Corp. 
Couldn't open device, some information will be missing
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               2.00
  bDeviceClass            0 
  bDeviceSubClass         0 
  bDeviceProtocol         0 
  bMaxPacketSize0        64
  idVendor           0x09e8 AKAI  Professional M.I. Corp.
  idProduct          0x004a 
  bcdDevice            0.00
  iManufacturer           1 
  iProduct                2 
  iSerial                 3 
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength       0x0012
    bNumInterfaces          1
    bConfigurationValue     1
    iConfiguration          0 
    bmAttributes         0x80
      (Bus Powered)
    MaxPower              500mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           0
      bInterfaceClass       255 Vendor Specific Class
      bInterfaceSubClass      0 
      bInterfaceProtocol      0 
      iInterface              0