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Conversion to SKiDL

A project log for CAT Board

The CAT Board is part of a Raspberry Pi-based hand-held FPGA programming system.

Dave VandenboutDave Vandenbout 05/04/2018 at 14:070 Comments

The first step in this resurrection was to convert the schematic-based CAT Board design into a SKiDL program. That was actually pretty easy. First, I generated a netlist from within EESCHEMA. Then I ran the following program to convert it into a SKiDL program:

netlist_to_skidl -i cat.net -o cat-flat.py

 While the conversion was easy, it's not exactly what I want. The resulting code is flat: just a list of component instantiations and nets to interconnect them without any hierarchical structure. Making changes to that is no easier than hacking on the actual netlist file.

The actual hierarchy for the CAT Board is shown below. It isn't a deep tree: just a bunch of peripherals attached to a central FPGA. But my goal is to make a parameterized SKiDL module for each peripheral. Then I can build not only the CAT Board by interconnecting those modules, but reuse them in other designs as part of a circuit library. A simple example would be an LED module that instantiates multiple LEDs and current-limiting resistors based upon the width of the bus entering the module.

So why did I bother making the flat version of the SKiDL code? Some of the motivation was to show the use of the netlist_to_skidl utility since it's an easy way to generate SKiDL for those used to working with schematics. In addition, the flat code also includes the detailed templates of the components used in the CAT Board. I can reuse those in my parameterized version.

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