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flat assembler > OS Construction > USB unresponsive device (EHCI)

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BAiC



Joined: 22 Mar 2011
Posts: 262
Location: California
I'm having some trouble with my test hardware. EHCI is reporting that a device is connected. I go through the USB Reset procedure and upon issuing a "Set Address" command the device simply doesn't respond. EHCI doesn't terminate with an error either (I initialized the error counter to 1 everywhere possible).

I am going to have to implement a timeout mechanism generally anyway but doing that won't solve the underlying problem here.

The only device plugged into any of my USB ports is the USB Floppy drive I use to boot so this behavior is very suspicious.

I booted into Windows (it's a DELL D520 laptop with WinXP): Windows doesn't have any issue with USB and the Device Manager doesn't report anything suspicious.

Has anyone seen this before?

Thanks.

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Post 30 Jul 2019, 15:41
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N-LG



Joined: 14 Feb 2019
Posts: 14
Location: france
i doesnt know a lot about USB (today my OS just detect the controler) but EHCI controler doesnt support low speed device and we need to use an slave UHCI or OHCI to use them
maybe the floppy drive is a low speed device?
Post 01 Aug 2019, 17:31
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BAiC



Joined: 22 Mar 2011
Posts: 262
Location: California
the floppy is a Full Speed device. the EHCI uses "Companion Controllers" that are either UHCI or OHCI to implement connections to the Root Hub. the EHCI can handle connections to Low Speed and Full Speed but they have to be connected to a non-root-hub.


my EHCI driver properly hands off the device to the Companion Controller when it first boots (for the floppy drive). this is a coincidence of the port enumerator: the Floppy Drive happens to be enumerated before the 'ghost' device.

I've since added a timeout function and a software port disable that blocks this 'ghost' device.

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Post 02 Aug 2019, 07:56
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N-LG



Joined: 14 Feb 2019
Posts: 14
Location: france
I can not wait to take care of the USB driver of my OS, it looks very complex, currently I take care of TCP connection management but the USB seems to be at a higher level

is that your work is available somewhere? I would like to take a look when i do my own future implementation of USB
Post 03 Aug 2019, 16:54
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BAiC



Joined: 22 Mar 2011
Posts: 262
Location: California
I stopped posting my code around the same time I created my own loader (i.e., ELF). it became so complex that I can't really ask for help with specific code blocks: most sections require knowledge of the OS in general in order to debug them.

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Post 04 Aug 2019, 20:35
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