RPLCD World Clock

clock.py

#!/usr/bin/env python3

from RPLCD.i2c import CharLCD
from pytz import timezone, utc
from datetime import datetime
from time import sleep, time as get_ts
from concurrent.futures import ThreadPoolExecutor


I2C_EXPANDER = "PCF8574"
I2C_ADDRS = [0x26, 0x27]
TIMEZONES = [
    timezone("America/Los_Angeles"),
    timezone("America/Denver"),
    timezone("America/Chicago"),
    timezone("America/New_York"),
    utc,
    timezone("Europe/Berlin"),
    timezone("Asia/Tokyo"),
    timezone("Australia/Sydney"),
]

with open("/etc/timezone") as f:
    local_tz = timezone(f.read().strip())

lcd0 = CharLCD(
    i2c_expander=I2C_EXPANDER,
    address=I2C_ADDRS[0],
    port=1,
    rows=4,
    cols=20,
    backlight_enabled=True
)

lcd1 = CharLCD(
    i2c_expander=I2C_EXPANDER,
    address=I2C_ADDRS[1],
    port=1,
    rows=4,
    cols=20,
    backlight_enabled=True
)

lcd0.clear()
lcd1.clear()

quit = False
with ThreadPoolExecutor(2) as pool:
    while not quit:
        try:
            lcd0.cursor = (0, 0)
            lcd1.cursor = (0, 0)

            now_ts = get_ts()
            now = local_tz.localize(datetime.fromtimestamp(now_ts))
            lcd_message0 = ""
            lcd_message1 = ""

            for idx, tz in enumerate(TIMEZONES):
                tz_str = tz.zone.split("/")[-1].replace("_", " ")
                time = now.astimezone(tz).strftime("%T")
                new_line = "{} {}".format(tz_str[:(20 - len(time))], time).rjust(20)
                if idx < 4:
                    lcd_message0 += new_line
                else:
                    lcd_message1 += new_line

            pool.submit(lcd0.write_string, lcd_message0)
            pool.submit(lcd1.write_string, lcd_message1)

            sleep(1 - now_ts % 1)

        except KeyboardInterrupt:
            quit = True

lcd0.close(clear=True)
lcd1.close(clear=True)

requirements.txt

RPLCD~=1.3.0
smbus2~=0.4.1
pytz~=2022.1