low-speed USB

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low-speed USB

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lpcware
NXP Employee
NXP Employee
Content originally posted in LPCWare by hens on Wed Apr 03 13:34:02 MST 2013
I moved the 1.5K pullup from usb_d+ to usb_d- in order to select 1.5Mbs, low-speed mode.  I also modified USBCLKDIV from 1 to 8, to generate 6MHz clock instead of 48MHz.  Low-speed USB device is not recognized.

Is there something else that I need to change?

The reason that I want low-speed is that I suspect I might have a signal fidelity issue on my USB path which is causing the problem reported in my previous thread, "LPC11U24 ISP via USB" (a thread without answers).  Aaaargggghhhh!
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lpcware
NXP Employee
NXP Employee
Content originally posted in LPCWare by hens on Wed Apr 03 16:48:26 MST 2013
Thanks Tsuneo.
I have reverted back to full-speed settings and will continue debug of the real problem in http://knowledgebase.nxp.com/showthread.php?t=4363 .
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lpcware
NXP Employee
NXP Employee
Content originally posted in LPCWare by Tsuneo on Wed Apr 03 16:01:55 MST 2013
The USB device controller on LPC11Uxx doesn't support low-speed. Just full-speed.

Tsuneo
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