topic Re: USB Bug? in MQX Software Solutions

USB Bug?

msinger — Fri, 02 Sep 2011 01:56:57 GMT

In host_dev_list.c on line 430 of MQX 3.7 is the call

status = _usb_host_ch9_get_descriptor((pointer)new_instance_ptr,
      USB_DESC_TYPE_DEV << 8, 0, 8,
      (uchar_ptr)&new_instance_ptr->dev_descriptor);

Should the "8" be an 18 as it's the length of the descriptor?

Re: USB Bug?

hchristo — Wed, 11 Jul 2012 00:08:09 GMT

did you solve this issue? i am trying to use the 3.6.1 usb stack in external ram (via mem_extend). the msd attaches, is supported, but the stack reports "unable to open USB disk".

the USB stack works ok for FAT-16 USB MSDs when run completely from internal ram.

Re: USB Bug?

c0170 — Wed, 11 Jul 2012 18:36:51 GMT

Hi msinger,

what you have found it's not bug. The device descriptor has size more than 8, according to specification. It is allowed to read only part of the descriptor.

It is an intention to read just 8 Bytes of the descriptor.

Regards,

MartinK