Shield  Fills  Generation
       ---------------------------


                                   Original Rev.  4-Mar-2025
                                    Current Rev.  6-Mar-2025


The DK board includes  Shield Fills  on L1 and L12 over the
PMT Analog Input Section.  The purpose of these Shields is
both to provide and additional copper layer of shielding in
this area of low level high-speed analog signals but also to
provide a path for any noise currents that flow on the outside
of the PMT coax cables to conduct these noise currents directly
to the main body of the DK's Ground Planes and thus avoid
having these currents flow through the Analog Ground Plane in 
low level Analog Input Section.

A complexity in the design of these Shield Fills is that to
control the current flows we want them connected to some of
the Ground Rivets in this area but not to others.  Control
of which ground rivets the shield fills connects to
is accomplished by assigning those rivets and the shield fills
themselves to the Net SHIELD while they are being generated
and the rest of the time assigning them to the Net GROUND.

This slight of hand is accomplished by the files:

    shield_connections_shield_net.txt
    shield_connections_ground_net.txt
    shield_connections.txt

Copy  shield_connections_shield_net.txt  to  shield_connections.txt
when you want these items assigned to the Net SHIELD  and
visa-versa.

The Shield Fills are generated by hand  (not by script)  and
are generated  before  (or is it after)  the other 46 Fills
are generated.


Procedure for generating the Shield Fills:
------------------------------------------

1. Set the Shield Fill components to use the Net Shield:

   Working in the Net List directory:

     copy  shield_connections_shield_net.txt  to  shield_connections.txt

   re-build the overall DK Net List by:

     ./aa_build_all_disco_nets_fcg1152.sh
     ./aa_disco_data_path_nets.sh


2. Generate the Shield Fills in Layout:

   Start Layout on the DK design and:

   Set the required Net Type Design Rules:

     Setup Routing  -->  Net Type Rules

       Select  Default_Net_Type  and  click "Change"

       Set:  Pin-Fill,  Via-Fill,  Trace-Fill  all to  0.4 mm
             and click "OK".   Click "Close" to exit this menue.


   Generate the  L1  Top  Shield Fill:

   Setup  --->  Shape Edit Mode ON

   Right panel memue  --->  Shape to Fill

     Select Shape at:  180.0  106.0

     Select:  Area Fill,  Layer: Signal_1,  Net: SHIELD,  Polygon,

              Manufacture Aperture Size:  0.1 mm

              Mininum Pad Slot Threshold:  0

              Solid,    Thermal Ties:

                        SMD FLOOD,  Pin FLOOD,  Via FLOOD

              Delete Original Shape:  NO


   Generate the  L12  Bottom  Shield Fill:

     The same as above but:

        Select Shape at:  178.5  105.5

        Select:  Layer: Signal_10


3. Restore the original  Default_Net_Type  Design Rules


4. Save the Traces file:

      File  -->  Save  -->  Design Specify

      Select Traces and save


5. Exit Layout without saving any other files.