USB_EVT_IN_NAK missing in action

Discussion created by lpcware Employee on Jun 15, 2016
Content originally posted in LPCWare by chris_bayley_trimble on Sun Aug 23 21:30:21 MST 2015
In using USBD ROM if I initialise the stack, register endpoint handlers, and EnableEvent(USB_EVT_IN_NAK & USB_EVT_OUT_NAK) on the endpoints BUT do NOT prime the endpoints I expect that the first events I will have to handle in the endpoint handler is an IN_NAK or OUT_NAK depending on the direction. I observe this to be true for the OUT_NAK but I get no event for an IN request when the EP is not primed. Is this the expected behaviour ?
How can I get a IN_NAK before the endpoint is primed ?
(I have some sleeping peripherals that I wish to wake upon arrival of the first NAK which will produce my USB data)