Working with PyEDA for solve questions of Digital Electronics
In this tutorial I will demonstrate some commands for using with Python to work with digital electronics. This tools is called PyEDA (Python Electronic Design Automation) and has some good features to use symbolic boolean algebra.
First of all let’s to install the library. I’m using Ubuntu system, so:
sudo apt install python3
sudo apt install python3-dev
sudo apt install python3-pip
pip3 install pyeda
Now you need import the library. If you are using Python REPL, try:
from pyeda.inter import *
To create the boolean variables use the command exprvar:
a = exprvar('a')
b = exprvar('b')
c,d = map(exprvar, "cd")
You can create boolean expressions using the operators: ~(NOT), & (AND), | (OR), ^ (XOR), >> (IMPLIES). For example:
s0 = a | b
s1 = (a & c) | (a & b)
s2 = ~(a | b & c)
s5 = expr("a | ~b & c")
Using the method equivalent we can test if the expressions are equals:
s0.equivalent(s1)
# Output: False
(~(a | b)).equivalent(~a & ~b)
# Output: True
You can create a Truth Table using the method truthtable:
j,k = map(exprvar, "jk")
t3 = truthtable([k,j], "1001")
# Output
# j k
# 0 0 : 1
# 0 1 : 0
# 1 0 : 0
# 1 1 : 1
X = exprvars('x', 3)
t4 = truthtable(X, "101011-1")
# Output:
# x[2] x[1] x[0]
# 0 0 0 : 1
# 0 0 1 : 0
# 0 1 0 : 1
# 0 1 1 : 0
# 1 0 0 : 1
# 1 0 1 : 1
# 1 1 0 : -
# 1 1 1 : 1
Now we can convert expressions to Truth Table and inverse:
s3 = truthtable2expr(t3)
# Output: Or(And(~j, ~k), And(j, k))
s4 = truthtable2expr(t4)
# Output: Or(And(~x[0], ~x[1], ~x[2]), And(~x[0], x[1], ~x[2]), And(~x[0], ~x[1], x[2]), And(x[0], ~x[1], x[2]), And(x[0], x[1], x[2]))
t0 = expr2truthtable(s0)
# Output:
# b a
# 0 0 : 0
# 0 1 : 1
# 1 0 : 1
# 1 1 : 1
t1 = expr2truthtable(s1)
# Output:
# c b a
# 0 0 0 : 0
# 0 0 1 : 0
# 0 1 0 : 0
# 0 1 1 : 1
# 1 0 0 : 0
# 1 0 1 : 1
# 1 1 0 : 0
# 1 1 1 : 1
Some utils method to expressions:
s4 = ~(~a & a) & ~(b | ~c)
s4.simplify()
# Output: Not(Or(b, ~c))
s4.to_nnf()
# Output: And(~b, c)