FPGA Design with Python and MyHDL
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The document presents a detailed overview of FPGA design using Python and MyHDL, highlighting the capabilities and advantages of each technology. It covers various aspects of Python such as syntax, data structures, and functions, while MyHDL is introduced as a Python-based hardware description language that simplifies hardware design and verification. Additionally, it addresses modeling, simulation, and conversion processes involved in MyHDL, along with some caveats and future enhancements.
![21.05.2014 30
MyHDL Signals
• Similar to VHDL signals
• Signal declaration:
s_empty = Signal(0)
s_count = Signal(intbv(0)[8:])
s_clk = Signal(bool(0))
• Signal assignment:
s_count.next = 0](https://image.slidesharecdn.com/2014allprogrammabedaysfpgadesignwithpython-140521102126-phpapp01/85/FPGA-Design-with-Python-and-MyHDL-30-320.jpg)
![21.05.2014 32
MyHDL intbv creation
Create an intbv:
intbv([val=None] [, min=None] [, max=None])
Example:
>>> a = intbv(24, min=0, max=25)
>>> a.min
0
>>> a.max
25
>>> len(a)
5](https://image.slidesharecdn.com/2014allprogrammabedaysfpgadesignwithpython-140521102126-phpapp01/85/FPGA-Design-with-Python-and-MyHDL-32-320.jpg)
![21.05.2014 33
MyHDL intbv indexing and slicing
Indexing:
>>> a = intbv(0x12)
>>> bin(a)
'10010'
>>> a[0]
False
>>> a[1]
True
Slicing:
>>> a = intbv(0x12)
>>> a[4:0]
intbv(2L)](https://image.slidesharecdn.com/2014allprogrammabedaysfpgadesignwithpython-140521102126-phpapp01/85/FPGA-Design-with-Python-and-MyHDL-33-320.jpg)
![21.05.2014 34
MyHDL intbv creation
Create an intbv, specifying its width:
>>> a = intbv(24)[5:]
>>> a.min
0
>>> a.max
32
>>> len(a)
5](https://image.slidesharecdn.com/2014allprogrammabedaysfpgadesignwithpython-140521102126-phpapp01/85/FPGA-Design-with-Python-and-MyHDL-34-320.jpg)
FPGA Design with Python and MyHDL
- 1. 21.05.2014 1 FPGA Design with Python and MyHDL Guy Eschemann
- 2. 21.05.2014 2 Content • About us • A short introduction to Python • Introduction to MyHDL • Demo • Questions
- 3. 21.05.2014 3 About noasic • Quick Facts – Founded in 2014 – 14+ years experience in FPGA design – Located in Kehl, Germany • Areas of expertise – FPGA & IP core design and verification – VHDL code generators
- 4. 21.05.2014 4 VHDL Code Generators (1)
- 5. 21.05.2014 5 VHDL Code Generators (2)
- 6. 21.05.2014 6
- 7. 21.05.2014 7 A short introduction to
- 8. 21.05.2014 8 Python • Created 1991 by Guido van Rossum at CWI (Netherlands) • General-purpose, high-level programming language • Emphasizes code readability • Write less code • Strongly, dynamically typed • Object-oriented • Open-source • Runs on many platforms
- 9. 21.05.2014 9 Sample Python code
- 10. 21.05.2014 10 Python – Syntax • Blocks are specified by indentation • No mandatory statement termination • Comments start with # • Assign values using = • Test equality using == • Increment/decrement using += or -=
- 11. 21.05.2014 11 Python – Data Structures • Lists – like one-dimensional arrays • Tuples – immutable, one-dimensional arrays • Dictionaries – associative arrays („hash tables“)
- 12. 21.05.2014 12 Python – Strings • Can use either single or double quotation marks • Multi-line strings enclosed in triple quotes • Use modulo (%) operator and a tuple to format a string
- 13. 21.05.2014 13 Python – Flow Control • Flow control statements: – if – for – while – there is no case/switch. Use „if“ instead.
- 14. 21.05.2014 14 Python – Functions • Declared with the „def“ keyword • Optional parameters supported • Functions can return multiple values
- 15. 21.05.2014 15 Python – Importing • External libaries (such as MyHDL) must be imported before they can be used: from myhdl import intbv OR from myhdl import *
- 16. 21.05.2014 16 Python Libraries • String handling • Regular expressions • Random number generation • Unit-test framework • OS interfacing • GUI development • Modules for math, database connections, network interfacing etc. • Hardware design (MyHDL)
- 18. 21.05.2014 18 MyHDL • Python-based hardware description language • Created 2003 by Jan Decaluwe • Open source
- 19. 21.05.2014 19 Why MyHDL? • Write less code • Avoid common VHDL and Verilog pitfalls • Apply modern SW development techniques to HW design • Can generate both VHDL and Verilog • Simulator included • Open source • Runs on many platforms (Windows, OSX, Linux) • Python ecosystem
- 20. 21.05.2014 20 What MyHDL is not • Not a way to turn arbitrary Python into silicon • Not a radically new approach • Not a synthesis tool • Not an IP block library • Not only for implementation • Not well suited for accurate timing simulations
- 21. 21.05.2014 21 MyHDL Design Flow
- 22. 21.05.2014 22 Example – 8 bit counter
- 23. 21.05.2014 23 Modeling Components • Components are modeled using functions • Function parameters map to ports
- 24. 21.05.2014 24 Modeling Processes • Processes are modeled using special „generator“ functions • Decorators are used to create generator functions
- 25. 21.05.2014 25 The @instance decorator • Most general, creates generator from a generator function a 1 0b z
- 26. 21.05.2014 26 The @always decorator • Abstracts an outer „while True“ loop followed by a „yield“ statement a 1 0b z
- 27. 21.05.2014 27 Combinational logic: @always_comb • Automatically infers the sensitivity list a 1 0b z
- 28. 21.05.2014 28 Sequential logic: @always_seq • Infers the reset functionality • Equivalent code:
- 29. 21.05.2014 29 Function Decorators • @instance: most general, multiple yields • @always: single yield, abstracts „while True“ loop • @always_comb: for asynchronous logic, automatically infers sensitivity list • @always_seq: for sequential logic, automatically infers the reset functionality
- 30. 21.05.2014 30 MyHDL Signals • Similar to VHDL signals • Signal declaration: s_empty = Signal(0) s_count = Signal(intbv(0)[8:]) s_clk = Signal(bool(0)) • Signal assignment: s_count.next = 0
- 31. 21.05.2014 31 MyHDL intbv class • Similiar to standard Python „int“ type with added indexing and slicing capabilities • intbv = „integer with bit-vector flavor“ • Provides access to underlying two‘s complement representation • Range of allowed values can be constrained
- 32. 21.05.2014 32 MyHDL intbv creation Create an intbv: intbv([val=None] [, min=None] [, max=None]) Example: >>> a = intbv(24, min=0, max=25) >>> a.min 0 >>> a.max 25 >>> len(a) 5
- 33. 21.05.2014 33 MyHDL intbv indexing and slicing Indexing: >>> a = intbv(0x12) >>> bin(a) '10010' >>> a[0] False >>> a[1] True Slicing: >>> a = intbv(0x12) >>> a[4:0] intbv(2L)
- 34. 21.05.2014 34 MyHDL intbv creation Create an intbv, specifying its width: >>> a = intbv(24)[5:] >>> a.min 0 >>> a.max 32 >>> len(a) 5
- 36. 21.05.2014 36 Generated VHDL code
- 37. 21.05.2014 37 Verification • Verification is MyHDL´s strongest point • Arguably the hardest part of hardware design • There are no restrictions for verification: can use the full power of Python • Can do „agile“ hardware design • The Foundation is an event-driven simulator in the MyHDL library
- 39. 21.05.2014 39 A basic MyHDL simulation
- 40. 21.05.2014 40 Debugging in MyHDL • Regular Python debugging • Waveform viewer output
- 41. 21.05.2014 41 Conversion • A subset of MyHDL can be automatically converted to VHDL and Verilog • The converter maintains the abstraction level • Supports some unique MyHDL features • Creates readable VHDL/Verilog • Convertible subset much broader than synthesizable subset
- 42. 21.05.2014 42 Conversion example • MyHDL Code • Conversion to Verilog • Conversion to VHDL • The converter does the casts and resizings automatically
- 45. 21.05.2014 45 Caveats • Dynamic nature of Python needs some getting used to • Error messages can be cryptic • Cannot import legacy VHDL/Verilog code – Write own behaviorals models for simulation – Use user-defined code for conversion • Cannot generate parameterizable HDL code
- 46. 21.05.2014 46 MyHDL future • Fixed-point support in the converter • Interfaces • Python 3.0 support
- 47. 21.05.2014 47 Resources • http://python.org • http://myhdl.org – Manual & examples – Download & installation instructions – Mailing list – Tutorials & publications • @MyHDL on twitter • Development with mercurial on Bitbucket
- 48. 21.05.2014 48 Contact Guy Eschemann noasic GmbH Sundheimer Feld 6 77694 Kehl guy@noasic.com http://noasic.com Twitter: @geschema