Enable the reading of the fifo fill counter via register read.
Add a sent JDRS packages counter to detect lost packages.
Only check the first byte received for a correct response.

The introduced package counter would mess up the check otherwise.
Separated JDRS header from response.

This way, the header is taken care of once and not for every response type individually.
Make IP and MAC address configurable and show it on the display.

It is configurably by the first 4 DIP switches on the board. If the configuration changes, the new values are shown for 10 seconds on the display.
Cleanup.
Adds a spill control register (right now with user button).

If the switch 5 is pressed, a simulated beam spill pause is initiated. As long as the button is pressed, the spill active register is set to '0' which can be read through a single register read.