Waveform Generators
set_sine : Set Sine Wave Frequency for WG, WGbar¶
set frequency of sine wave on WG. Restores waveform type to sine if some other shape had been previously set. WGbar output will also output a sine wave which is 180 degrees out of phase with WG at all times.
| parameter | description |
|---|---|
| frequency | 4 to 5000 . Freq in Hz |
invokes p.set_wave(freq, 'sine') under the hood.
p.set_wave(100) # 100 Hz sine wave on WG
set_wave : Set Frequency and type of WG waveform out¶
set frequency of wave on WG. Also sets waveform type to ‘sine’/’tria’.
| parameter | description |
|---|---|
| frequency | 4 to 5000 . Freq in Hz |
| type | ‘sine’ or ‘tria’ |
p.set_wave(freq, 'sine')
set_sine_amp : Set Sine Wave Amplitude¶
Set the amplitude of the waveform output on WG
| parameter | description |
|---|---|
| value | 2 1x amplitude (3.3V) |
| 1 1V | |
| 0 100mV |
p.set_sine_amp(2) #3.3 V amplitude. +/-3.3V swing
load_equation : Load a shape from a function¶
p.load_equation(function, span=None, **kwargs)
Evaluates function over span at 512 points, normalizes the result, and uploads it to WG. Then set the playback rate with set_wave / set_sine.
| parameter | description |
|---|---|
| function | 'sine', 'tria', np.sin, or any callable f(x) |
| span | [xmin, xmax] over which to evaluate (required for custom callables; presets pick their own) |
| amp | optional keyword (default 0.95) — scales peak PWM duty (passed through to load_table) |
p.load_equation('tria') # built-in triangle
p.load_equation(np.sin, [0, 2 * np.pi])
p.set_wave(400)
Fourier approximation of a square wave
import numpy as np
from matplotlib import pyplot as plt
import eyes17.eyes
p = eyes17.eyes.open()
# Connect WG → A1
def f1(x):
return np.sin(x) + np.sin(3 * x) / 3
p.load_equation(f1, [0, 2 * np.pi])
p.set_wave(400)
x, y = p.capture1('A1', 500, 10)
plt.plot(x, y)
plt.show()
load_table : Load 512 raw samples to WG¶
p.load_table(points, mode='arbit', **kwargs)
Upload an arbitrary waveform table. Values are min–max normalized and scaled to the PWM lookup table.
| parameter | description |
|---|---|
| points | Sequence of exactly 512 samples (any numeric scale; will be normalized) |
| mode | 'arbit' (default), 'sine', or 'tria' — stored as p.WaveType |
| amp | Peak scale 0–1 (default 0.95) |
import numpy as np
# Sawtooth
p.load_table(np.arange(512), mode='arbit')
p.set_wave(200)
# Custom table from an equation (manual)
xs = np.linspace(0, 2 * np.pi, 512, endpoint=False)
p.load_table(np.sin(xs) ** 3, amp=0.9)
p.set_wave(500)
After loading, use p.set_wave(freq) (or set_sine) to set how fast the table is scanned. Amplitude of the analog output is still governed by set_sine_amp for the WG path.
set_sq1 : Set Square Wave Frequency for SQ1¶
set_sqr1(self, freq, duty_cycle=50)
set frequency of square wave on SQ1.
| parameter | description |
|---|---|
| frequency | 0.02 to 100000 . Freq in Hz |
| duty_cycle | 0 to 100. default 50 |
Set a 1KHz square wave (0 to 5V) output on SQ1 with 10% duty cycle.
p.set_sq1(1000,10)
set_sq2 : Set Square Wave Frequency for SQ2¶
set_sqr2(self, freq, duty_cycle=50)
set frequency of square wave on SQ2.
Warning
This will disable the sine wave output on WG. invoking set_sine will restore the sine wave and disable this.
| parameter | description |
|---|---|
| frequency | 0.02 to 100000 . Freq in Hz |
| duty_cycle | 0 to 100. default 50 |
p.set_sq2(1000)
Fourier Transformation demo
Connect WG to A1, and SQ1 to A2¶
import eyes17.eyes
p = eyes17.eyes.open()
from matplotlib import pyplot as plt
from eyes17 import eyemath17 as em
p.set_sine(1000)
p.set_sqr1(500)
t,v, tt,vv = p.capture2(5000, 20) # captures A1 and A2
plt.xlabel('Freq')
plt.ylabel('Amplitude')
plt.xlim([0,10000])
#0.001 is to convert 20uS to mS units
xa,ya = em.fft(v,20*0.001)
plt.plot(xa,ya, linewidth = 2, color = 'blue')
xa,ya = em.fft(vv, 20*0.001)
plt.plot(xa, ya, linewidth = 2, color = 'red')
plt.show()