CircuitPython code for https://adafruit-playground.com/u/jepler/pages/e-ink-countdown-in-circuitpython-with-custom-stand

code.py

import os
import math
import sys
import time

import alarm
import board
import displayio
import socketpool
import rtc
import wifi
from fourwire import FourWire

import adafruit_datetime
import adafruit_ntp
import adafruit_ssd1680
import adafruit_lc709203f

from font_orbitron_medium_webfont_54_latin1 import FONT
from adafruit_display_text.bitmap_label import Label

def connect_wifi():
    if wifi.radio.ipv4_address is None:
        print("connect wifi")
        print(os.getenv('WIFI_SSID'), os.getenv('WIFI_PASSWORD'))
        for _ in range(5):
            try:
                wifi.radio.connect(os.getenv('WIFI_SSID'), os.getenv('WIFI_PASSWORD'))
                return
            except Exception as e:
                print(e)

# This pinout works on a Metro M4 and may need to be altered for other boards.
spi = board.SPI()  # Uses SCK and MOSI
epd_cs = board.D9
epd_dc = board.D10
epd_reset = None
epd_busy = None



def setup_display():
    global display, group

    displayio.release_displays()

    display_bus = FourWire(
        spi, command=epd_dc, chip_select=epd_cs, reset=epd_reset, baudrate=1000000
    )
    time.sleep(1)

    # For issues with display not updating top/bottom rows correctly set colstart to 8
    display = adafruit_ssd1680.SSD1680(
        display_bus,
        height=250,
        width=122,
        busy_pin=epd_busy,
        highlight_color=0x000000,
        colstart=0,
        rotation=180,
        black_bits_inverted=1
    )

    group = displayio.Group()
    display.root_group = group


def main():
    battery_monitor = adafruit_lc709203f.LC709203F(board.I2C())
    for _ in range(5):
        try:
            percent = battery_monitor.cell_percent
            break
        except Exception as e:
            print(e)
    else:
        print("too much battery polling")
        percent = 100

    if percent < 5: return 86400

    target = adafruit_datetime.datetime(2025, 3, 28, 21)  # UTC, 4PM local time

    sm0 = alarm.sleep_memory[0]
    if sm0 == 0:
        # Assumes wifi connected via settings.toml before code.py started!
        connect_wifi()
        pool = socketpool.SocketPool(wifi.radio)
        ntp = adafruit_ntp.NTP(pool, tz_offset=0, cache_seconds=3600, socket_timeout=1)
        for _ in range(10):
            try:
                rtc.RTC().datetime = ntp.datetime
                alarm.sleep_memory[0] = 24 # Don't set again for about 24h
                break
            except Exception as e:
                print(e)
        else:
            print("NTP too much")
            # Hopefully it's better in a few hundred seconds
            return 300
    else:
        print(f"Don't need to set for {sm0} hours")
        alarm.sleep_memory[0] = sm0-1

    labels = [
        Label(
            FONT,
            text="",
            anchor_point=(0.5, 0.5),
            anchored_position=(display.width // 2, display.height * (i + 0.5) // 3),
        )
        for i in range(4)
    ]
    for l in labels:
        group.append(l)

    for _ in range(10):
        try:
            now = adafruit_datetime.datetime.now()
            break
        except Exception as e:
            print(e)
    else:
        print("NTP too much")
        # Hopefully it's better in a few hundred seconds
        return 300

    delta = target - now
    delta = adafruit_datetime.timedelta(
        seconds=math.ceil(delta.total_seconds() / 3600) * 3600
    )
    weeks = delta.days // 7
    days = delta.days % 7
    hours = delta.seconds // 3600

    low_bat = percent < 25

    if delta.total_seconds() < 0:
        labels[0].text = "GO"
        labels[1].text = "GO"
        labels[2].text = "GO"
    else:
        labels[0].text = f"{weeks}"
        labels[1].text = f"{days}"
        labels[2].text = "bat!" if low_bat else f"{hours}"

    t0 = time.time()
    display.refresh()
    t1 = time.time()

    if delta.total_seconds() < 0:
        return sys.maxsize
    if low_bat:
        # Sleep until tomorrow to preserve the battery...
        sleep_until = (now + adafruit_datetime.timedelta(seconds=86400)).replace(
            hour=6, minute=0, second=0
        )
    else:
        # Sleep a bit into the next hour, it's just fine to be 90 seconds late,
        # but avoid waking if somehow we get 90 seconds of clock skew within
        # the next hour...
        sleep_until = (now + adafruit_datetime.timedelta(seconds=3600)).replace(
            minute=1, second=30
        )
    return (sleep_until - now).total_seconds()


if __name__ == "__main__":
    to_sleep = 300
    try:
        setup_display()
        to_sleep = main()
    finally:
        displayio.release_displays()
        print(f"sleeping for {to_sleep} seconds")
        alarm.exit_and_deep_sleep_until_alarms(
            alarm.time.TimeAlarm(monotonic_time=time.monotonic() + to_sleep)
        )