2. 2
1. HDL Overview, Verilog Keywords and Syntax, Data Types and Operators,
2. Verilog Statements, Wire and gate-level Keywords, Structure of a Verilog Program :
3. Modules, ports, and signals, Specifying Boolean Expressions:
4. Example of gate instantiation (AND, NAND, OR, NOR, XOR, XNOR), User Defined
Primitives,
5. Verilog Examples: (Full Adder, 2-to-1 multiplexer , 2-to-4 decoder, 4- bit
comparator),
6. Modelling Circuit Delay,
7. Modelling Sequential Elements: blocking and non-blocking assignment,
8. sequential circuit elements, and registers,
9. Verilog Examples: (Verilog – D Flip-flop, Verilog – D Flip-flop with Reset,
10. Test bench Stimulus
Hardware Description Language Programming
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Outline
3. ¿VHDL & Verilog?
Hardware description language (HDL) is a specialized computer
language used to describe the structure and behavior of electronic
circuits, and most commonly, digital logic circuits.
There are two most common Hardware Description Languages (HDL)
used by integrated circuit (IC) designers.
Verilog HDL
VHDL.
They are each a notation to describe the behavioral and structural
aspects of an electronic digital circuit.
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4. VHDL Background
VHSIC Hardware Description Language.
VHSIC is an abbreviation for Very High Speed Integrated Circuit.
Developed by the department of defense (1981)
In 1986 rights where given to IEEE
• Became a standard and published in 1987
• Revised standard we know now published in 1993 (VHDL 1076-1993)
regulated by VHDL international (VI)
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5. VHDL
Uses top-down approach to partition design into small blocks
‘components’
Entity: describes interface signals & basic building blocks
Architecture: describes behavior, each entity can have
multiple Architectures
Configuration: sort of parts list for a design, which behavior
to use for each entity.
Package: toolbox used to build design
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7. • VHDL represents another high level language for digital
system design.
• In this course we study Verilog HDL
– reason:
• used more often in electronic and computer industry
• programming style is very similar to C programming
language
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8. Verilog Background
Developed by Gateway Design Automation (1980)
Later acquired by Cadence Design(1989) who made
it public in 1990
Became a standardized in 1995 by IEEE (Std 1364)
regulated by Open Verilog International (OVI)
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Gateway Design Automation. The company was privately held at that time by Dr. Prabhu
Goel, the inventor of the PO in 1985 DEM (Path-Oriented Decision Making) test generation
algorithm.[1] Verilog HDL was designed by Phil Moorby who was later to become the Chief
Designer for Verilog-XL
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9. • Verilog only has one building block
– Module: modules connect through their port similarly as
in VHDL
– Usually there is only one module per file.
– A top level invokes instances of other modules.
– Modules can be specified behaviorally or structurally.
• Behavioral specification defines behavior of digital system
• Structural specification defines hierarchical interconnection of
sub modules
VERILOG
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module f_adder_1
(
input x,
input y,
input c_in,
output A,
output c_out
);
assign A = x ^ y ^ c_in;
assign c_out = (x & y) | ((x^y) & c_in);
endmodule
An Example of Verilog HDL Cde
11. • Verilog Hardware Description Language(HDL)
– A high-level computer language can model, represent and simulate digital
design
• Hardware concurrency
• Parallel Activity Flow
• Semantics for Signal Value and Time
– Design examples using Verilog HDL
• Intel Pentium, AMD K5, K6, Atheon, ARM7, etc
• Thousands of ASIC designs using Verilog HDL
What is Verilog HDL?
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12. The “standard” languages are:
Very similar
Many tools provide front-ends to both
Verilog is “simpler”
Less syntax, fewer constructs
VHDL supports large, complex systems
Better support for modularization
More grungy details
“Hello world” is much bigger in VHDL
Verilog/VHDL
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13. • These languages have taken designers from low level detail to
much higher level of abstraction.
• In 2000 VI & OVI merged into Accellera
• Simulation & synthesis are the two main kinds of tools which
operate on the VHDL & Verilog languages.
• They are not a toolset or methodology they are each a different
language.
– However toolsets and methodologies are essential for their effective use.
Similarities
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14. • There are not many differences as to the capabilities of
each.
• The choice of which one to use is often based in personal
preference & other issues such as availability of tools &
commercial terms.
• VHDL is “harder” to learn ADA-like.
• Verilog is “easier” to learn C-like.
Differences?
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15. Field Programmable Gate Array
A Fully configurable IC
FPGAs contain programmable logic components called logic blocks.
Contain hierarchy of reconfigurable interconnects that allow the blocks to be
wired together.
Logic Blocks can be configured to any complex circuit.
FPGA can be made to work as a Xor gate, a Counter or even bigger- an
entire Processor!
FPGA
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