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  USBXpress library and Low Speed

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Author Topic:   USBXpress library and Low Speed
fmcbm
New Member 		posted August 23, 2010 03:57 AM     Click Here to See the Profile for fmcbm     Edit/Delete Message
Hi,
in order to reduce the supply current of my messurement device (using the USBXpress library) I would like to set the usb clock from 48 MHz (full speed) to 6 MHz (low speed). So I set the USBCLK to Internal Oscillator / 2: USBCLK = 001b
Now the enumeration fails and windows says the device does not work correctly. May it be, that the USB-Lib does not support Low Speed? In the application note of USBXpress there is only talk of Full Speed...

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Tsuneo
Member 		posted August 25, 2010 10:27 PM     Click Here to See the Profile for Tsuneo   Click Here to Email Tsuneo     Edit/Delete Message
> May it be, that the USB-Lib does not support Low Speed?

No, it doesn't.
USBXpress stands on bulk transfer. Bulk transfer is not allowed on low-speed.

For low-speed, HID is available.
Start with one of HID examples on the SiLabs examples folder.

Tsuneo

[This message has been edited by Tsuneo (edited August 26, 2010).]

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