USB Bug?

[msinger]

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?

[c0170 · Accepted solution]

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

[hchristo]

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.