Waveform Block Equations for Timing Diagram Editors

Sine, Capacitor, Ramp and Exponential waveforms can be inserted into a waveform segment using a Waveform Equation Block. Unlike the State Label equations of the next section which append analog waveform segments onto the end of a signal, waveform equation blocks can edited after they are created. For this reason, it's generally better to use a waveform equation block rather than a State Label equation.

Many functions have Code already written

Flyout has default code for several WaveForm Block Equations

Some Default Waveform Block Equations

WaveForm Block Equations can appear in consecutive segments on a waveform

Checking the View > Show Waveform Block Highlights menu will draw blue boxes around all of the Waveform Equation Blocks.

Consecutive Waveform Block Equations used to make complex waveforms

Many functions can be written by editing and combining code from the default codes

Capacitor Charging and Discharging

"""Cap smoothed square wave"""
period_ns = 100.0
period_ps = period_ns * 1000.0

sampleT = (currentT - startT) % (period_ps / 2)
rc_constant_ns = 10.0
amplitude_v = 5.0
# determine whether we're on the charge or discharge half of the cycle
charge = int((currentT - startT) / (period_ps / 2)) % 2 == 0

rc_constant_ps = 1000.0 * rc_constant_ns
import math
if charge:
  return amplitude_v * (1.0 - math.exp(-sampleT/rc_constant_ps))
else:
  return amplitude_v * math.exp(-sampleT/rc_constant_ps)

Clipped Sinewave

"""Clipped Sine wave"""
sampleT = currentT - startT
sin_amplitude_v = 10.0
clipping_amplitude_v = 5.0
period_ns = 50.0

import math
# convert Display Time Units to Base Time Units
# this example assumes DTU = ns & BTU = ps
period_ps = period_ns * 1000.0

sin_value = sin_amplitude_v * math.sin(2.0*math.pi*sampleT/period_ps)
return max(-clipping_amplitude_v, min(clipping_amplitude_v, sin_value))

Code your own Waveform Block Equations using Python math functions

Square Waveform

"""Fourier series for a square wave"""
# increase "k" below to get a closer approximation of 
# a square wave
import math
sampleT = currentT - startT
amplitude_v = 5.0
period_ns = 50.0
k = 7

period_ps = period_ns * 1000.0

return sum([1.0/n * math.sin(2.0*math.pi*n*sampleT/period_ps) for n in range(1,k+1,2)])

Waveform Block Equations can label digital signals

"""Counts upwards from start by step with prepended prefix"""
prefix = 'S'
start = 0
step = 1

index = int((currentT - startT)/deltaT) - 1
value = start + step*index
return prefix + str(value)