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USB CDC on LPC1768 problem

Lukasz Gesieniec

Hi,

I have a problem with running a USB-CDC on the LPC1768. I have a USB circuit identical to the MCB1700 board. I use the sample code for USBCDC MCB1700 board.
My program stops at the following line:
while (! USB_Configuration);
On the computer I get the message: "USB Device not Recognized."
Is it a hardware or rather a software problem? Sorry for my English.

Best Regards,
Lukas

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  • 0 in reply to Lukasz Gesieniec

    Can I guess that you have read the user manual for your processor? At least the USB section since you knew you had problems with the USB?

    It specifies that usbclk must be 48MHz from the USB clock divider, to create the 12MHz bus speed. A 12MHz crystal makes it easy to let the PLL step up the frequency by a factor 4 and feed the USB logic. What PLL settings did you use? What usbclk frequency did you get with your settings?

Reply
  • 0 in reply to Lukasz Gesieniec

    Can I guess that you have read the user manual for your processor? At least the USB section since you knew you had problems with the USB?

    It specifies that usbclk must be 48MHz from the USB clock divider, to create the 12MHz bus speed. A 12MHz crystal makes it easy to let the PLL step up the frequency by a factor 4 and feed the USB logic. What PLL settings did you use? What usbclk frequency did you get with your settings?

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