import math
from pyb import DAC

ch = 1

# create a buffer containing a sine-wave
buf = bytearray(100)
for i in range(len(buf)):
    buf[i] = 128 + int(127 * math.sin(2 * math.pi * i / len(buf)))

# output the sine-wave at 600Hz
dac = DAC(ch, bits=8)
dac.write_timed(buf, 600 * len(buf), mode=DAC.CIRCULAR)

import math
from array import array
from pyb import DAC

ch = 2

# create a buffer containing a sine-wave, using half-word samples
buf = array('H', 2048 + int(2047 * math.sin(2 * math.pi * i / 128)) for i in range(128))

# output the sine-wave at 400Hz
dac = DAC(ch, bits=12)
dac.write_timed(buf, 400 * len(buf), mode=DAC.CIRCULAR)