VHDL or Verilog?
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Timers block
Hi. In this series of articles, we will experiment with the definition, implementation, simulation and synthesis of a block of timers in VHDL. Along the way, we will: Test the VHDL code blocks using Vivado simulator. Synthesize and implement the VHDL code on Xilinx's Zynq FPGA. Originally this project was used on a relatively small FPGA. The logic for the timers didn't fit so I used the internal memory to implement the solution. In many of my designs I have seen that it is the LUTs (and not the FFs or the internal RAM) what tends to be under heavy utilization. So using the block RAM to implement register (or timers) banks can be a way to fit a design into a device. So first, let's start with the code for a single timer component: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 library ieee ; use ieee.std_logic_1164.all ; use ieee.numeric_std.all ; entity...
Analysis, elaboration and synthesis
Do you recognize that feeling when you think you knew something, until somebody asks you to explain it? Well, that was what happened to me when I tried to explain what "Analysis and Elaboration" is. I used it in FPGA tools many times, and I had a certain "knowledge" of what it was, but, what are those processes EXACTLY? And, while we are at it, we will also describe what Synthesis is. Let's see: Analysis Analysis is the process where the design files are checked for syntactic and semantic errors. The syntactic rules are dictated by the language. On VHDL, if you write IF but forget to include the THEN clause, that is a violation of the syntax , the set of rules of the VHDL language. Semantics are the meaning of the language. A sentence describing an addition is tagged as incorrect if the operands are of incompatible types and the VHDL compiler cannot resolve the meaning of that sentence. Elaboration VHDL designs are hierarchic by natur...