MPFS250T  FCVG784  BGA  Geometry   Rev. 3
    -------------------------------------------


                                           Original Date:   9-Mar-2023
                                            Current Date:   9-Mar-2023


The goals of this version of the geometry for the PolarFire
MPFS250T-FCVG784  are:

 - Start from a basic 4 quadrant geometry with an appropriate
   default  SMD Pad plus Via  pin/pad stack for each quadrant.

   This is the  Rev. 2  of the MPFS250T-FCVG784 geometry.


 - Remove the  SMD Pad plus Via  pin/pad stack  from all
   unused pins on the device   and   from all pins that
   have a trace that escapes on the top layer of the pcb.

   Replace these  SMD Pad plus Via  pin/pad stack  with
   just a default  SMD Pad Only  pin/pad stack.

   * A list of unused device pins that will have an
     SMD Pad Only  pin/pad stack   comes from the
     single pin nets for U1 in the sorted net list.

   * A hand entered file that lists all of the used pins
     that have their associated trace escape on the top
     layer is used to identify the second group of pins
     that need a  SMD Pad Only  pin/pad stack.

        pin_numbers_of_in_use_pins_with_smd_pad_only.txt

   * The  SMD Pad Only  pin/pad stacks are placed by the
     X,Y location of the SMD Pad  (not offset to the Via).


What is NOT being attempted so far in this Rev. 3
geometry is to worry about the many different types of 
SMD Pad plus Via  pin/pad stacks that will eventually be
needed for the active pins in each quadrant, e.g.

  normal signal with normal via,
  high-speed signal with small via,
  power/ground with thick dog-bone and normal via



Instructions to Build  Rev 3  of the FCVG784:

 - Building the  Rev. 3  version of this geometry assumes
   that you have already build a  Rev. 1  version and a
   Rev. 2  version  and  that these geometry files are in
   their appropriate sub-directories.   Once Rev 1  and
   Rev 2  have been built you do NOT need to rebuild them
   every time you build a new version of Rev 3.


 - Run the script   build_rev_3_tailored_fcvg784_geom.sh

   to build a  Tailored  Rev 3  version of the fcvg784
   geometry.  In this case all of the U1 FPGA pins that
   are indicated as  Single Pin Nets  in the  Sorted NetList
   file   and   in the file

      pin_numbers_of_in_use_pins_with_smd_pad_only.txt

   will have a  SMD Pad Only  pin/pad stacks.