はじめに

Enviro環境センサボードとは以下の各センサとカラーLCDをオールインワンに搭載したRaspberry Pi HATである。

BME280：温度、気圧、湿度センサ
LTR-559：明るさ、近接センサ
MEMSマイクロフォン：騒音センサ
160x80pixcel 0.96インチカラーLCD（ST7735互換と思われる）
ADS1015：ADコンバータ

ちなみに、実験結果から**#4**と印刷された端子は、Raspberry PiのGPIO 23（物理ピン#16）に直結している。

この上位製品で、さらに空気品質センサを追加したEnviro+空気品質センサボードもある。

MICS6814：ガスセンサ
PMS5003：粒子状物質センサ（PM1、PM2.5、PM10を検出）（ただし、別売）

このボードを駆動させるためにコードを書く必要があるが、発売元から各センサを操作するPythonライブラリが公開されている。さらにライブラリの使用例としてサンプルコードも公開されていて、この中の一つがweather-and-light.pyである。先頭の画像のLCDに映っている下記内容をリアルタイムに表示するプログラムである。

左上（10:10）　　現在の時刻
左上部（20°C）　現在の温度
左下部（55%）　　現在の湿度
右上（15 Nov 19）現在の日付
右上部（10,000）　現在の照度
右下部（1,025）　現在の気圧
背景色（オレンジ）日の出〜日の入（日中）、日が沈むと（夜間の）背景は黒

これだけで十分価値のあるコードであるが、上記の日付時刻が英国シェフィールド市基準となっている。これを日本(東京)基準に変更するのが、今回の目的である。

基準都市の変更

コードを読めば一目瞭然であるが、weather-and-light.pyの行309〜310で都市を設定しているので、これを変更する。

オリジナル

# The city and timezone that you want to display.
city_name = "Sheffield"
time_zone = "Europe/London"

変更後

# The city and timezone that you want to display.
city_name = "Tokyo"
time_zone = "Asis/Tokyo"

都市を横浜にしたかったのだが、astral.geocoderライブラリのdatabaseにYokohamaが無かったのでTokyoとした。

日付・時刻の表示フォーマットの変更

日付表示が欧米仕様であるが、日本人には 年.月.日の方が馴染みがあるので、フォーマットも変更する。また、各情報はリアルタイムに更新されるので、時刻に秒を追加する。weather-and-light.pyの行359〜360で設定しているので、これを変更する.

オリジナル

date_string = local_dt.strftime("%d %b %y").lstrip('0')
time_string = local_dt.strftime("%H:%M")

変更後

date_string = local_dt.strftime("%Y.%m.%d")
time_string = local_dt.strftime("%H:%M:%S")

趣味の問題だが、「左に日付、右に時刻」の方がしっくりくるので、さらに行361〜362も変更して左右を入れ替えることにする。

オリジナル

img = overlay_text(background, (0 + margin, 0 + margin), time_string, font_lg)
img = overlay_text(img, (WIDTH - margin, 0 + margin), date_string, font_lg, align_right=True)

変更後

img = overlay_text(background, (0 + margin, 0 + margin), date_string, font_lg)
img = overlay_text(img, (WIDTH - margin, 0 + margin), time_string, font_lg, align_right=True)

sleepを入れる

元のコードは全力で無限ループしているので、手持ちのRaspberry Pi Zero Wだと、CPU利用率が93.8%と高止まりとなる。そこでループ最後に500ミリ秒sleepを入れます。

コードの最終行に追加

time.sleep(0.5) # 500ms sleep

（ところが、約92%にしか下がらない。CPU利用率が高い理由は別にありそうだ！）

無事に変更できました。

変更後の全コードも掲載しておきます。

ここに表示

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

f"Sorry! This program requires Python >= 3.6 😅"

import os
import time
import numpy
import colorsys
from PIL import Image, ImageDraw, ImageFont, ImageFilter
from fonts.ttf import RobotoMedium as UserFont

import ST7735
from bme280 import BME280
from ltr559 import LTR559

import pytz
from pytz import timezone
from astral.geocoder import database, lookup
from astral.sun import sun
from datetime import datetime, timedelta

try:
    from smbus2 import SMBus
except ImportError:
    from smbus import SMBus


def calculate_y_pos(x, centre):
    """Calculates the y-coordinate on a parabolic curve, given x."""
    centre = 80
    y = 1 / centre * (x - centre) ** 2

    return int(y)


def circle_coordinates(x, y, radius):
    """Calculates the bounds of a circle, given centre and radius."""

    x1 = x - radius  # Left
    x2 = x + radius  # Right
    y1 = y - radius  # Bottom
    y2 = y + radius  # Top

    return (x1, y1, x2, y2)


def map_colour(x, centre, start_hue, end_hue, day):
    """Given an x coordinate and a centre point, a start and end hue (in degrees),
       and a Boolean for day or night (day is True, night False), calculate a colour
       hue representing the 'colour' of that time of day."""

    start_hue = start_hue / 360  # Rescale to between 0 and 1
    end_hue = end_hue / 360

    sat = 1.0

    # Dim the brightness as you move from the centre to the edges
    val = 1 - (abs(centre - x) / (2 * centre))

    # Ramp up towards centre, then back down
    if x > centre:
        x = (2 * centre) - x

    # Calculate the hue
    hue = start_hue + ((x / centre) * (end_hue - start_hue))

    # At night, move towards purple/blue hues and reverse dimming
    if not day:
        hue = 1 - hue
        val = 1 - val

    r, g, b = [int(c * 255) for c in colorsys.hsv_to_rgb(hue, sat, val)]

    return (r, g, b)


def x_from_sun_moon_time(progress, period, x_range):
    """Recalculate/rescale an amount of progress through a time period."""

    x = int((progress / period) * x_range)

    return x


def sun_moon_time(city_name, time_zone):
    """Calculate the progress through the current sun/moon period (i.e day or
       night) from the last sunrise or sunset, given a datetime object 't'."""

    city = lookup(city_name, database())

    # Datetime objects for yesterday, today, tomorrow
    utc = pytz.utc
    utc_dt = datetime.now(tz=utc)
    local_dt = utc_dt.astimezone(pytz.timezone(time_zone))
    today = local_dt.date()
    yesterday = today - timedelta(1)
    tomorrow = today + timedelta(1)

    # Sun objects for yesterday, today, tomorrow
    sun_yesterday = sun(city.observer, date=yesterday)
    sun_today = sun(city.observer, date=today)
    sun_tomorrow = sun(city.observer, date=tomorrow)

    # Work out sunset yesterday, sunrise/sunset today, and sunrise tomorrow
    sunset_yesterday = sun_yesterday["sunset"]
    sunrise_today = sun_today["sunrise"]
    sunset_today = sun_today["sunset"]
    sunrise_tomorrow = sun_tomorrow["sunrise"]

    # Work out lengths of day or night period and progress through period
    if sunrise_today < local_dt < sunset_today:
        day = True
        period = sunset_today - sunrise_today
        # mid = sunrise_today + (period / 2)
        progress = local_dt - sunrise_today

    elif local_dt > sunset_today:
        day = False
        period = sunrise_tomorrow - sunset_today
        # mid = sunset_today + (period / 2)
        progress = local_dt - sunset_today

    else:
        day = False
        period = sunrise_today - sunset_yesterday
        # mid = sunset_yesterday + (period / 2)
        progress = local_dt - sunset_yesterday

    # Convert time deltas to seconds
    progress = progress.total_seconds()
    period = period.total_seconds()

    return (progress, period, day, local_dt)


def draw_background(progress, period, day):
    """Given an amount of progress through the day or night, draw the
       background colour and overlay a blurred sun/moon."""

    # x-coordinate for sun/moon
    x = x_from_sun_moon_time(progress, period, WIDTH)

    # If it's day, then move right to left
    if day:
        x = WIDTH - x

    # Calculate position on sun/moon's curve
    centre = WIDTH / 2
    y = calculate_y_pos(x, centre)

    # Background colour
    background = map_colour(x, 80, mid_hue, day_hue, day)

    # New image for background colour
    img = Image.new('RGBA', (WIDTH, HEIGHT), color=background)
    # draw = ImageDraw.Draw(img)

    # New image for sun/moon overlay
    overlay = Image.new('RGBA', (WIDTH, HEIGHT), color=(0, 0, 0, 0))
    overlay_draw = ImageDraw.Draw(overlay)

    # Draw the sun/moon
    circle = circle_coordinates(x, y, sun_radius)
    overlay_draw.ellipse(circle, fill=(200, 200, 50, opacity))

    # Overlay the sun/moon on the background as an alpha matte
    composite = Image.alpha_composite(img, overlay).filter(ImageFilter.GaussianBlur(radius=blur))

    return composite


def overlay_text(img, position, text, font, align_right=False, rectangle=False):
    draw = ImageDraw.Draw(img)
    w, h = font.getsize(text)
    if align_right:
        x, y = position
        x -= w
        position = (x, y)
    if rectangle:
        x += 1
        y += 1
        position = (x, y)
        border = 1
        rect = (x - border, y, x + w, y + h + border)
        rect_img = Image.new('RGBA', (WIDTH, HEIGHT), color=(0, 0, 0, 0))
        rect_draw = ImageDraw.Draw(rect_img)
        rect_draw.rectangle(rect, (255, 255, 255))
        rect_draw.text(position, text, font=font, fill=(0, 0, 0, 0))
        img = Image.alpha_composite(img, rect_img)
    else:
        draw.text(position, text, font=font, fill=(255, 255, 255))
    return img


def get_cpu_temperature():
    with open("/sys/class/thermal/thermal_zone0/temp", "r") as f:
        temp = f.read()
        temp = int(temp) / 1000.0
    return temp


def correct_humidity(humidity, temperature, corr_temperature):
    dewpoint = temperature - ((100 - humidity) / 5)
    corr_humidity = 100 - (5 * (corr_temperature - dewpoint))
    return min(100, corr_humidity)


def analyse_pressure(pressure, t):
    global time_vals, pressure_vals, trend
    if len(pressure_vals) > num_vals:
        pressure_vals = pressure_vals[1:] + [pressure]
        time_vals = time_vals[1:] + [t]

        # Calculate line of best fit
        line = numpy.polyfit(time_vals, pressure_vals, 1, full=True)

        # Calculate slope, variance, and confidence
        slope = line[0][0]
        intercept = line[0][1]
        variance = numpy.var(pressure_vals)
        residuals = numpy.var([(slope * x + intercept - y) for x, y in zip(time_vals, pressure_vals)])
        r_squared = 1 - residuals / variance

        # Calculate change in pressure per hour
        change_per_hour = slope * 60 * 60
        # variance_per_hour = variance * 60 * 60

        mean_pressure = numpy.mean(pressure_vals)

        # Calculate trend
        if r_squared > 0.5:
            if change_per_hour > 0.5:
                trend = ">"
            elif change_per_hour < -0.5:
                trend = "<"
            elif -0.5 <= change_per_hour <= 0.5:
                trend = "-"

            if trend != "-":
                if abs(change_per_hour) > 3:
                    trend *= 2
    else:
        pressure_vals.append(pressure)
        time_vals.append(t)
        mean_pressure = numpy.mean(pressure_vals)
        change_per_hour = 0
        trend = "-"

    # time.sleep(interval)
    return (mean_pressure, change_per_hour, trend)


def describe_pressure(pressure):
    """Convert pressure into barometer-type description."""
    if pressure < 970:
        description = "storm"
    elif 970 <= pressure < 990:
        description = "rain"
    elif 990 <= pressure < 1010:
        description = "change"
    elif 1010 <= pressure < 1030:
        description = "fair"
    elif pressure >= 1030:
        description = "dry"
    else:
        description = ""
    return description


def describe_humidity(humidity):
    """Convert relative humidity into good/bad description."""
    if 40 < humidity < 60:
        description = "good"
    else:
        description = "bad"
    return description


def describe_light(light):
    """Convert light level in lux to descriptive value."""
    if light < 50:
        description = "dark"
    elif 50 <= light < 100:
        description = "dim"
    elif 100 <= light < 500:
        description = "light"
    elif light >= 500:
        description = "bright"
    return description


# Initialise the LCD
disp = ST7735.ST7735(
    port=0,
    cs=1,
    dc=9,
    backlight=12,
    rotation=270,
    spi_speed_hz=10000000
)

disp.begin()

WIDTH = disp.width
HEIGHT = disp.height

# The city and timezone that you want to display.
city_name = "Tokyo"
time_zone = "Asia/Tokyo"

# Values that alter the look of the background
blur = 50
opacity = 125

mid_hue = 0
day_hue = 25

sun_radius = 50

# Fonts
font_sm = ImageFont.truetype(UserFont, 12)
font_lg = ImageFont.truetype(UserFont, 14)

# Margins
margin = 3


# Set up BME280 weather sensor
bus = SMBus(1)
bme280 = BME280(i2c_dev=bus)

min_temp = None
max_temp = None

factor = 2.25
cpu_temps = [get_cpu_temperature()] * 5

# Set up light sensor
ltr559 = LTR559()

# Pressure variables
pressure_vals = []
time_vals = []
num_vals = 1000
interval = 1
trend = "-"

# Keep track of time elapsed
start_time = time.time()

while True:
    path = os.path.dirname(os.path.realpath(__file__))
    progress, period, day, local_dt = sun_moon_time(city_name, time_zone)
    background = draw_background(progress, period, day)

    # Time.
    time_elapsed = time.time() - start_time
    date_string = local_dt.strftime("%Y.%m.%d")
    time_string = local_dt.strftime("%H:%M:%S")
    img = overlay_text(background, (0 + margin, 0 + margin), date_string, font_lg)
    img = overlay_text(img, (WIDTH - margin, 0 + margin), time_string, font_lg, align_right=True)

    # Temperature
    temperature = bme280.get_temperature()

    # Corrected temperature
    cpu_temp = get_cpu_temperature()
    cpu_temps = cpu_temps[1:] + [cpu_temp]
    avg_cpu_temp = sum(cpu_temps) / float(len(cpu_temps))
    corr_temperature = temperature - ((avg_cpu_temp - temperature) / factor)

    if time_elapsed > 30:
        if min_temp is not None and max_temp is not None:
            if corr_temperature < min_temp:
                min_temp = corr_temperature
            elif corr_temperature > max_temp:
                max_temp = corr_temperature
        else:
            min_temp = corr_temperature
            max_temp = corr_temperature

    temp_string = f"{corr_temperature:.0f}°C"
    img = overlay_text(img, (68, 18), temp_string, font_lg, align_right=True)
    spacing = font_lg.getsize(temp_string)[1] + 1
    if min_temp is not None and max_temp is not None:
        range_string = f"{min_temp:.0f}-{max_temp:.0f}"
    else:
        range_string = "------"
    img = overlay_text(img, (68, 18 + spacing), range_string, font_sm, align_right=True, rectangle=True)
    temp_icon = Image.open(f"{path}/icons/temperature.png")
    img.paste(temp_icon, (margin, 18), mask=temp_icon)

    # Humidity
    humidity = bme280.get_humidity()
    corr_humidity = correct_humidity(humidity, temperature, corr_temperature)
    humidity_string = f"{corr_humidity:.0f}%"
    img = overlay_text(img, (68, 48), humidity_string, font_lg, align_right=True)
    spacing = font_lg.getsize(humidity_string)[1] + 1
    humidity_desc = describe_humidity(corr_humidity).upper()
    img = overlay_text(img, (68, 48 + spacing), humidity_desc, font_sm, align_right=True, rectangle=True)
    humidity_icon = Image.open(f"{path}/icons/humidity-{humidity_desc.lower()}.png")
    img.paste(humidity_icon, (margin, 48), mask=humidity_icon)

    # Light
    light = ltr559.get_lux()
    light_string = f"{int(light):,}"
    img = overlay_text(img, (WIDTH - margin, 18), light_string, font_lg, align_right=True)
    spacing = font_lg.getsize(light_string.replace(",", ""))[1] + 1
    light_desc = describe_light(light).upper()
    img = overlay_text(img, (WIDTH - margin - 1, 18 + spacing), light_desc, font_sm, align_right=True, rectangle=True)
    light_icon = Image.open(f"{path}/icons/bulb-{light_desc.lower()}.png")
    img.paste(humidity_icon, (80, 18), mask=light_icon)

    # Pressure
    pressure = bme280.get_pressure()
    t = time.time()
    mean_pressure, change_per_hour, trend = analyse_pressure(pressure, t)
    pressure_string = f"{int(mean_pressure):,} {trend}"
    img = overlay_text(img, (WIDTH - margin, 48), pressure_string, font_lg, align_right=True)
    pressure_desc = describe_pressure(mean_pressure).upper()
    spacing = font_lg.getsize(pressure_string.replace(",", ""))[1] + 1
    img = overlay_text(img, (WIDTH - margin - 1, 48 + spacing), pressure_desc, font_sm, align_right=True, rectangle=True)
    pressure_icon = Image.open(f"{path}/icons/weather-{pressure_desc.lower()}.png")
    img.paste(pressure_icon, (80, 48), mask=pressure_icon)

    # Display image
    disp.display(img)

    time.sleep(0.5) # 500ms sleep

おわりに

pythonを知っている方なら、ほんの数分で出来るたやすい変更だと思いますが、自分への備忘録としてここに残しておくことにしました。

以上