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LPC4330 recognize High Speed Device as Low Speed Device

Question asked by Yasushi Aoyama on Sep 20, 2017
Latest reply on Oct 19, 2017 by Yasushi Aoyama

Hi All,


 I'm developing USB host function for USB high speed devices.  I have a trouble of recognizing USB speed.  LPC4330 recognize some high speed device as low speed devices.  I'd appreciate if somebody could advice me.


Environment) H/W: LPC4330 Explore Board

                     SW:  lpcopen_3_01_lpcxpresso_ngx_xplorer_4330


 Problem) Some high speed device is recognized low speed device. Some device can be recognized as high speed device correctly.  It's depends on device model.  Not depends on timing nor individual


 I checked PORTSC1_H register when port status change occurs.(Device Connect) 

 (A)The high speed device correctly recognized, PORTSC1_H value is 0x30001803.

  PSPD(b27:26) = 00  Full Speed

  LS(b11:10)= 10: Not Low Speed


 (B)The high speed device recognized as Low speed,  PORTSC1_H value is 0x34001803

  PSPD(b27:26) = 01  Low Speed

  LS(b11:10)= 10: Not Low Speed


In (A) case, after bus reset, device chirp and hub chirp occurs and the device becomes High speed device.

In (B) case, after bus reset, device chirp occurs but hub chirp doesn't occur, the device remain low speed device.


Yasushi Aoyama