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wh.py
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wh.py
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import time
import threading
import math
import RPi.GPIO as GPIO
import ioexpander as io
from bme280 import BME280
from ltr559 import LTR559
from smbus2 import SMBus
from .history import wind_degrees_to_cardinal
__version__ = '0.0.1'
# Wind Vane
PIN_WV = 8 # P0.3 ANE6
# Anemometer
PIN_ANE1 = 5 # P0.0
PIN_ANE2 = 6 # P0.1
ANE_RADIUS = 7 # Radius from center to the center of a cup, in CM
ANE_CIRCUMFERENCE = ANE_RADIUS * 2 * math.pi
ANE_FACTOR = 2.18 # Anemometer factor
# Rain gauge
PIN_R2 = 3 # P1.2
PIN_R3 = 7 # P1.1
PIN_R4 = 2 # P1.0
PIN_R5 = 1 # P1.5
RAIN_MM_PER_TICK = 0.2794
wind_direction_to_degrees = {
0.9: 0,
2.0: 45,
3.0: 90,
2.8: 135,
2.5: 180,
1.5: 225,
0.3: 270,
0.6: 315
}
class WeatherHAT:
def __init__(self):
self.updated_wind_rain = False
self._lock = threading.Lock()
self._i2c_dev = SMBus(1)
self._bme280 = BME280(i2c_dev=self._i2c_dev)
self._ltr559 = LTR559(i2c_dev=self._i2c_dev)
self._ioe = io.IOE(i2c_addr=0x12, interrupt_pin=4)
# Fudge to enable pull-up on interrupt pin
self._ioe._gpio.setup(self._ioe._interrupt_pin, GPIO.IN, pull_up_down=GPIO.PUD_UP)
# Input voltage of IO Expander, this is 3.3 on Breakout Garden
self._ioe.set_adc_vref(3.3)
# Wind Vane
self._ioe.set_mode(PIN_WV, io.ADC)
# Anemometer
self._ioe.set_mode(PIN_ANE1, io.OUT)
self._ioe.output(PIN_ANE1, 0)
self._ioe.set_pin_interrupt(PIN_ANE2, True)
self._ioe.setup_switch_counter(PIN_ANE2)
# Rain Sensor
self._ioe.set_mode(PIN_R2, io.IN_PU)
self._ioe.set_mode(PIN_R3, io.OUT)
self._ioe.set_mode(PIN_R4, io.IN_PU)
self._ioe.setup_switch_counter(PIN_R4)
self._ioe.set_mode(PIN_R5, io.IN_PU)
self._ioe.output(PIN_R3, 0)
self._ioe.set_pin_interrupt(PIN_R4, True)
self._ioe.on_interrupt(self.handle_ioe_interrupt)
self._ioe.clear_interrupt()
# Data API... kinda
self.temperature_offset = -7.5
self.device_temperature = 0
self.temperature = 0
self.pressure = 0
self.humidity = 0
self.relative_humidity = 0
self.dewpoint = 0
self.lux = 0
self.wind_speed = 0
self.wind_direction = 0
self.rain = 0
self.rain_total = 0
self.reset_counts()
def reset_counts(self):
self._lock.acquire(blocking=True)
self._ioe.clear_switch_counter(PIN_ANE2)
self._ioe.clear_switch_counter(PIN_R4)
self._lock.release()
self._wind_counts = 0
self._rain_counts = 0
self._last_wind_counts = 0
self._last_rain_counts = 0
self._t_start = time.time()
def compensate_humidity(self, humidity, temperature, corrected_temperature):
"""Compensate humidity.
Convert humidity to relative humidity.
"""
dewpoint = self.get_dewpoint(humidity, temperature)
corrected_humidity = 100 - (5 * (corrected_temperature - dewpoint)) - 20
return min(100, max(0, corrected_humidity))
def get_dewpoint(self, humidity, temperature):
"""Calculate Dewpoint."""
return temperature - ((100 - humidity) / 5)
def hpa_to_inches(self, hpa):
"""Convert hextopascals to inches of mercury."""
return hpa * 0.02953
def degrees_to_cardinal(self, degrees):
value, cardinal = min(wind_degrees_to_cardinal.items(), key=lambda item: abs(item[0] - degrees))
return cardinal
def update(self, interval=60.0):
# Time elapsed since last update
delta = time.time() - self._t_start
self.updated_wind_rain = False
# Always update TPHL & Wind Direction
self._lock.acquire(blocking=True)
self.device_temperature = self._bme280.get_temperature()
self.temperature = self.device_temperature + self.temperature_offset
self.pressure = self._bme280.get_pressure()
self.humidity = self._bme280.get_humidity()
self.relative_humidity = self.compensate_humidity(self.humidity, self.device_temperature, self.temperature)
self.dewpoint = self.get_dewpoint(self.humidity, self.device_temperature)
self.lux = self._ltr559.get_lux()
self.wind_direction_raw = self._ioe.input(PIN_WV)
self._lock.release()
value, self.wind_direction = min(wind_direction_to_degrees.items(), key=lambda item: abs(item[0] - self.wind_direction_raw))
# Don't update rain/wind data until we've sampled for long enough
if delta < interval:
return
self.updated_wind_rain = True
rain_hz = self._rain_counts / delta
wind_hz = self._wind_counts / delta
self.rain_total = self._rain_counts * RAIN_MM_PER_TICK
self.reset_counts()
# wind speed of 2.4km/h causes the switch to close once per second
wind_hz /= 2.0 # Two pulses per rotation
wind_cms = wind_hz * ANE_CIRCUMFERENCE * ANE_FACTOR
self.wind_speed = wind_cms / 100.0
self.rain = rain_hz * RAIN_MM_PER_TICK
def handle_ioe_interrupt(self, pin):
self._lock.acquire(blocking=True)
self._ioe.clear_interrupt()
wind_counts, _ = self._ioe.read_switch_counter(PIN_ANE2)
rain_counts, _ = self._ioe.read_switch_counter(PIN_R4)
# If the counter value is *less* than the previous value
# then we know the 7-bit switch counter overflowed
# We bump the count value by the lost counts between last_wind and 128
# since at 127 counts, one more count will overflow us back to 0
if wind_counts < self._last_wind_counts:
self._wind_counts += 128 - self._last_wind_counts
self._wind_counts += wind_counts
else:
self._wind_counts += wind_counts - self._last_wind_counts
self._last_wind_counts = wind_counts
if rain_counts < self._last_rain_counts:
self._rain_counts += 128 - self._last_rain_counts
self._rain_counts += rain_counts
else:
self._rain_counts += rain_counts - self._last_rain_counts
self._last_rain_counts = rain_counts
# print(wind_counts, rain_counts, self._wind_counts, self._rain_counts)
self._lock.release()