wind_direction_byo.py

from gpiozero import MCP3008
import time
import math

adc = MCP3008(channel=0)
count = 0
values = []


volts = {
    0.4: 0.0,
    1.4: 22.5,
    1.2: 45.0,
    2.8: 67.5,
    2.7: 90.0,
    2.9: 112.5,
    2.2: 135.0,
    2.5: 157.5,
    1.8: 180.0,
    2.0: 202.5,
    0.7: 225.0,
    0.8: 247.5,
    0.1: 270.0,
    0.3: 292.5,
    0.2: 315.0,
    0.6: 337.5,
}


def get_average(angles):
    sin_sum = 0.0
    cos_sum = 0.0

    for angle in angles:
        r = math.radians(angle)
        sin_sum += math.sin(r)
        cos_sum += math.cos(r)

    flen = float(len(angles))
    s = sin_sum / flen
    c = cos_sum / flen
    arc = math.degrees(math.atan(s / c))
    average = 0.0

    if s > 0 and c > 0:
        average = arc
    elif c < 0:
        average = arc + 180
    elif s < 0 and c > 0:
        average = arc + 360

    return 0.0 if average == 360 else average


def get_value(length=5):
    data = []
    print("Measuring wind direction for %d seconds..." % length)
    start_time = time.time()

    while time.time() - start_time <= length:
        wind = round(adc.value * 3.3, 1)
        if not wind in volts:  # keep only good measurements
            print("unknown value " + str(wind))
        else:
            data.append(volts[wind])

    return get_average(data)