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import math
from pyaudio import PyAudio, paUInt8

def generate_sine_wave(frequency, duration, volume=0.2, sample_rate=22050):
    ''' Generate a tone at the given frequency.

        Limited to unsigned 8-bit samples at a given sample_rate.
        The sample rate should be at least double the frequency.
    '''
    if sample_rate < (frequency * 2):
        print('Warning: sample_rate must be at least double the frequency '
              f'to accurately represent it:\n    sample_rate {sample_rate}'
              f' ≯ {frequency*2} (frequency {frequency}*2)')

    num_samples = int(sample_rate * duration)
    rest_frames = num_samples % sample_rate

    pa = PyAudio()
    stream = pa.open(
        format=paUInt8,
        channels=1,  # mono
        rate=sample_rate,
        output=True,
    )

    # make samples
    s = lambda i: volume * math.sin(2 * math.pi * frequency * i / sample_rate)
    samples = (int(s(i) * 0x7F + 0x80) for i in range(num_samples))

    # write several samples at a time
    for buf in zip( *([samples] * sample_rate) ):
        stream.write(bytes(buf))

    # fill remainder of frameset with silence
    stream.write(b'\x80' * rest_frames)

    stream.stop_stream()
    stream.close()
    pa.terminate()

generate_sine_wave(
    # see http://www.phy.mtu.edu/~suits/notefreqs.html
    frequency=440,   # Hz, waves per second C6
    duration=0.2,       # seconds to play sound
    volume=0.25,        # 0..1 how loud it is
    sample_rate=44100,  # number of samples per second: 11025, 22050, 44100
)