1-to-4 Demultiplexer

Information

A 1-to-4 demultiplexer (DEMUX) is a digital circuit that takes a single input and routes it to one of four outputs, depending on the values of two select lines (Sel0 and Sel1).

Selection logic:

• Sel1 Sel0 = 00 → Out0 = In

• Sel1 Sel0 = 01 → Out1 = In

• Sel1 Sel0 = 10 → Out2 = In

• Sel1 Sel0 = 11 → Out3 = In

Truth Table

Ports

• In: Input signal

• Sel0: Least significant select bit

• Sel1: Most significant select bit

• Out0–Out3: Four output signals

Model

The DEMUX1to4 model implements a 1-input, 2-select digital demultiplexer.

Attributes:

• In (dsignal): Input digital signal

• Sel0, Sel1 (dsignal): Select lines

• Out0–Out3 (dsignal): Four output lines

Methods:

digital(): Routes the input signal to one of the outputs based on Sel1 and Sel0:

from pyams.lib import dsignal, model

class DEMUX1to4(model):
    """ 1-to-4 Demultiplexer """
    def __init__(self, In, Sel0, Sel1, Out0, Out1, Out2, Out3):
        self.In = dsignal(direction='in', port=In)
        self.Sel0 = dsignal(direction='in', port=Sel0)
        self.Sel1 = dsignal(direction='in', port=Sel1)
        self.Out0 = dsignal(direction='out', port=Out0)
        self.Out1 = dsignal(direction='out', port=Out1)
        self.Out2 = dsignal(direction='out', port=Out2)
        self.Out3 = dsignal(direction='out', port=Out3)

    def digital(self):
        """ Perform DEMUX logic """
        s0 = self.Sel0
        s1 = self.Sel1
        self.Out0 += ~s1 & ~s0 & self.In
        self.Out1 += ~s1 & s0 & self.In
        self.Out2 += s1 & ~s0 & self.In
        self.Out3 += s1 & s0 & self.In

Command syntax

The syntax for defining a 1-to-4 demultiplexer in a PyAMS simulation:

# Import the model
from pyams.models import DEMUX1to4

# DEMUX: instance name
# In: input; Sel0, Sel1: select lines; Out0–Out3: outputs
DEMUX = DEMUX1to4(In, Sel0, Sel1, Out0, Out1, Out2, Out3)