USTAT USB_USTAT UIR.TRNIF

#USB Registers.

##USTAT 
The SIE Transaction status register, it is only valid when the TRNIF interrupt
flag is asserted.  USTAT is a four byte fifo.
USTAT contains the endpoint number, and IN/OUT direction.

##USB_USTAT
This is a copy for the microcontroller of the USTAT buffer, take a copy while
the SIE is under management of the microcontroller.

##TRNIF
Interrupt flag to show that USTAT is valid.  When TRNIF is cleared USTAT is 
moved onto the next of its four bytes.

##USB_bytes_left
This is a user managed byte
    
##USB_BufferDescriptor 4 bytes long
This is the buffer descriptor.

##USB_buffer_data   8 bytes long.
Must be the data....


UIR, UERRIF
UIR, ACTVIF
UIR, SOFIF
USB_USWSTAT
UIR, URSTIF

USB_error_flags
USB_buffer_desc

BD0OBC 
BD0IST
BD0OST 

Funciton to handle the clear.
Function to handle the status bulbs.



Describe.
---------
IN vs OUT 
    In - Informs the USB device that the host wishes to read information.
    Out - Informs the USB device that the host wishes to send information. 
DATA0/DATA1


SOF
    The SOF packet consists of an 11-bit frame number is sent by the host every 1 ms ± 500 ns.




StandardRequests this handles the setup request from the host.
Here the host might request a descriptor.
So the PIC updates the usb buffers to hold that descriptor such that at the next frame
the IN TOKEN from the host will mean that the descriptor is send.

(Above might be incorrect and needs confirmed.) VERY IMPORTANT TO UNDERSTAND.

The next frame the device needs to respond from ProcessInToken with the requested data.
lsusb -v -d 04d8:0014



wireshark filter ' usb.device_address == 46'  the 46 might increment each time the dev is 
unplugged, number comes from the fourth column of 'lsusb'




#TODO
Get the Data1/Data0 input output working correctly.

Move to interrupts handling the USB operations.
so that the main thread can do other things.

Check which version of LibUsB is used on the 
Why are there warnings on the laptop when I compile.

Learn a little more about LibUSB, how to
continously get interrupts processed.