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51
USB / Re: Understanding HID communication
« Last post by jhinkle on November 19, 2022, 05:20:32 pm »
Thanks -- but I was asking about the 3 bytes before the data packet.  69  81  58

I suspect the 81 means IN EP1  and I suspect 58 might be a CRC -- I don't know how to decode 69.
52
USB / Re: Understanding HID communication
« Last post by Renate on November 19, 2022, 11:04:51 am »
The "IN txn" is giving you the summary, what this whole transaction is about without showing the raw packets.
Those 8 bytes are the same 8 bytes defined in your HID report descriptor.
It says no buttons, hat returns 0xf, 4 x joystick in center range 0x80 and one pad byte.
Since you're not using it, there is no report ID.

You can see it all packed into the DATA0 packet, once you strip the header and the CRC.

I don't know hats off-hand but you've got 4 bits and a logical maximum of 7.
Did you mean -8 to +7 or 0 to +15?
53
USB / Understanding HID communication
« Last post by jhinkle on November 18, 2022, 11:19:10 am »
I am trying to understand a USB Game pad interface with a game box.

I have used a Beagle to capture the USB activity.

I have walked myself thru all the Descriptors and End Point transfers and now attempting to understand the EP 1 (IN) - comm.

All values are hexadecimal

Identified as "IN Packet"  69 81 58

Identified as ""DATA0 Packet"  C3 00 00 0F 80 80 80 80 00 F7 3D

My question is HOW to decode the "IN Packet"



How is 69 broken down and interpreted?  Same with 81 and 58.

Do any of the values reflect a HID Item Tag?

The following is the associated HID Descriptor:

0x05, 0x01,        // Usage Page (Generic Desktop Ctrls)
0x09, 0x05,        // Usage (Game Pad)
0xA1, 0x01,        // Collection (Application)
0x15, 0x00,        //   Logical Minimum (0)
0x25, 0x01,        //   Logical Maximum (1)
0x35, 0x00,        //   Physical Minimum (0)
0x45, 0x01,        //   Physical Maximum (1)
0x75, 0x01,        //   Report Size (1)
0x95, 0x0E,        //   Report Count (14)
0x05, 0x09,        //   Usage Page (Button)
0x19, 0x01,        //   Usage Minimum (0x01)
0x29, 0x0E,        //   Usage Maximum (0x0E)
0x81, 0x02,        //   Input (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position)
0x95, 0x02,        //   Report Count (2)
0x81, 0x01,        //   Input (Const,Array,Abs,No Wrap,Linear,Preferred State,No Null Position)
0x05, 0x01,        //   Usage Page (Generic Desktop Ctrls)
0x25, 0x07,        //   Logical Maximum (7)
0x46, 0x3B, 0x01,  //   Physical Maximum (315)
0x75, 0x04,        //   Report Size (4)
0x95, 0x01,        //   Report Count (1)
0x65, 0x14,        //   Unit (System: English Rotation, Length: Centimeter)
0x09, 0x39,        //   Usage (Hat switch)
0x81, 0x42,        //   Input (Data,Var,Abs,No Wrap,Linear,Preferred State,Null State)
0x65, 0x00,        //   Unit (None)
0x95, 0x01,        //   Report Count (1)
0x81, 0x01,        //   Input (Const,Array,Abs,No Wrap,Linear,Preferred State,No Null Position)
0x26, 0xFF, 0x00,  //   Logical Maximum (255)
0x46, 0xFF, 0x00,  //   Physical Maximum (255)
0x09, 0x30,        //   Usage (X)
0x09, 0x31,        //   Usage (Y)
0x09, 0x32,        //   Usage (Z)
0x09, 0x35,        //   Usage (Rz)
0x75, 0x08,        //   Report Size ( 8 )
0x95, 0x04,        //   Report Count (4)
0x81, 0x02,        //   Input (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position)
0x75, 0x08,        //   Report Size ( 8 )
0x95, 0x01,        //   Report Count (1)
0x81, 0x03,        //   Input (Const,Var,Abs,No Wrap,Linear,Preferred State,No Null Position)
0xC0,              // End Collection


Thanks in advance for any comments.
54
USB / Re: USB binterval
« Last post by danwaqar on November 04, 2022, 01:16:12 pm »
from this link

https://www.freelists.org/post/wdmaudiodev/USB20-High-speed-audio-device-for-windows-XP


I found the reason . There is no issue with my device rather limitation in Win audio usb driver with binterval 1

if device is USB Audio Class 1 then the binterval 1 which utilizes HS USB to full extent will not work. The USB audio class 1 will only work at usb FS. The way out is to have USB audio Class 2.0 implemented. My question is can I just do it by modifying the descriptors?
55
USB / Re: Type C video alt modes & Billboard USB class
« Last post by Renate on October 29, 2022, 08:45:06 am »
Just a quick comment if you're wondering if your Android device supports Type C DisplayPort:
You can:
Code: [Select]
C:\>adb shell
$ zcat /proc/config.gz | grep TYPEC
See if it says CONFIG_TYPEC_DP_ALTMODE=y or if it's commented out (#) or missing.
56
USB / Re: USB binterval
« Last post by Jan Axelson on October 28, 2022, 10:39:42 pm »
A protocol analyzer may help isolate the problem. Start by ensuring that the device enumerated successfully.

http://janaxelson.com/development_tools.htm#analyzers
57
USB / Re: Type C video alt modes & Billboard USB class
« Last post by Jan Axelson on October 28, 2022, 10:37:45 pm »
Sorry to say I have no insights on this. - Jan
58
USB / USB binterval
« Last post by danwaqar on October 26, 2022, 02:02:50 pm »
In my composite USB device (HID+Audio)
I am seeing that setting the speaker (OUT) endpoint bInterval to 1 on USB 2.0 Speed and USB Audio 1.1 spec
The device works fine on Linux but on Windows no streaming. Upon inspection I saw no output packets going from Windows host machine to my USB device. Why is that?
As per spec Windows should recognize the binterval 1 which is a packet every 125us.
Please guide
59
USB / Type C video alt modes & Billboard USB class
« Last post by Renate on October 24, 2022, 01:58:52 pm »
It seems that Mac notebooks and Chromebooks support DisplayPort alt mode over USB Type C.
Beyond that, things get very muddled.

There are five possible video alt modes over USB Type C:
  • DisplayPort
  • HDMI
  • MHL
  • Thunderbolt
  • VirtualLink
It seems to me that whether a particular device supports one of these requires first that the processor supports USB 3.x and further that it supports the specific video mode.
This information seems very hard to find out, even for a single manufacturer.
The Qualcomm Snapdragon 730G, 845 and 855 appear to support DisplayPort. Any others?

Usually switching to video alt modes requires PD communication over a CC line.
There is also the fallback of the Billboard USB class over the USB 2.0 data lines.
How universally is the Billboard USB class supported? Is it guaranteed if a video alt mode is supported?
Also, there are no class-specific requests. Why didn't they throw us a sop and have current video alt mode reported?

I will get some active adapters to try out some stuff, but in the interim I wanted to throw together a Billboard device.
I wouldn't do anything with the video data coming down on the SS pairs. I merely want to see if I can get to see some reaction in the dmesg.

Has anybody home-brewed PD control messages?

Any thoughts?
60
USB / Re: Windows & USB, problems & two utilities
« Last post by Renate on August 15, 2022, 04:27:07 am »
I think that we may be miscommunicating.

Of course enumusb.exe works with HID devices.
Maybe you mean how do you "friendly" name interfaces? Specify the /i (interface) flag along with the /v and the /p.
Collections are a whole other level and aren't enumerated when enumerating interfaces.
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