How to limit USB 2.0 channels to Full-speed

cancel
Showing results for 
Show  only  | Search instead for 
Did you mean: 

How to limit USB 2.0 channels to Full-speed

1,324 Views
admin
Specialist II

Saved FAQ from Freescale.com for information only:

Topic: USB

 

Question.  How to limit USB 2.0 channels to Full-speed (12Mbit)?

 

Answer.  Software should set the PFSC bit (bit 24) in the PORTSC register during USB controller init and prior to setting the RS bit in the USBCMD register (start controller). The port will than work in full speed only. However, the ULPI interface speed will remain 60 MHz so the CLK will still be at 60 MHz.

 

To avoid issues one may try to use non-high speed (if present) PC USB port.  Also please check (USB) device descriptors, what options are supported. Particularly, pay attention on bcdUSB field (USB spec Release Number - if set for 1.1 the host will not try high speed).

 

 Related Products:

 i.MX Applications Processors > i.MX51 Processors > i.MX512, i.MX513, i.MX514, i.MX515, i.MX516

Tags (1)
0 Kudos
Reply
0 Replies