LPC Microcontrollersのトピックlow speed USB on lpc11u14?

low speed USB on lpc11u14?

lpcware — Wed, 15 Jun 2016 19:42:38 GMT

Content originally posted in LPCWare by kingsob on Mon Jun 09 04:52:34 MST 2014
I have built a custom board that uses a lap11u14, and I am able to get the full speed USB examples working correctly.

I have no need for full speed USB in my project, and don't really want to include an external oscillator just for full speed USB support, especially when low speed would work fine.

I have searched around for hours, and can not find any low speed USB examples. Does the lpc11u14 support low speed (the data sheet seems to imply that it does)?

the only post I could find was

http://www.lpcware.com/content/forum/usb-low-speed-mode-lpc11u14

but am not sure how to update USB descriptors.

any help would be greatly appreciated.

Re: low speed USB on lpc11u14?

lpcware — Wed, 15 Jun 2016 19:42:39 GMT

Content originally posted in LPCWare by xianghuiwang on Fri Jun 13 14:32:28 MST 2014

Hi, Kingsob,

Below zip file can provide you with the low speed descriptor for the lpc11u14.

Even though this package is for the crystal-less low speed lpc11u6x operation, the low speed descriptor applies to the lpc11u14 as well.

Regards,

Re: low speed USB on lpc11u14?

lpcware — Wed, 15 Jun 2016 19:42:39 GMT

Content originally posted in LPCWare by kingsob on Mon Jun 16 02:04:38 MST 2014
Thank you! I have gotten the generic hid example working with low speed using the LPC11U14. Now I need to get things working with the UART example, but you have given me a great starting point

I notice this comment in quite a few locations. Is this specific to the LPC11U6x? or is it required with the LPC11U14 as well?

/*WORKAROUND for artf44835 ROM driver BUG:
    Code clearing STALL bits in endpoint reset routine corrupts memory area
    next to the endpoint control data. For example When EP0, EP1_IN, EP1_OUT,
    EP2_IN are used we need to specify 3 here. But as a workaround for this
    issue specify 4. So that extra EPs control structure acts as padding buffer
    to avoid data corruption. Corruption of padding memory doesn’t affect the
    stack/program behaviour.
 */