Low power Adafruit IO data logger with always-on LCD display

code.py

import board
import digitalio
import rtc
import time
import alarm
import ssl
import wifi
import socketpool
import adafruit_requests

from adafruit_io.adafruit_io import IO_HTTP
from adafruit_lc709203f import LC709203F
from adafruit_bme280 import basic as adafruit_bme280
from oso_lcd.lcdwing_lite import LCDWingLite, Indicator

try:
    from secrets import secrets
except ImportError:
    print("WiFi secrets are kept in secrets.py, please add them there!")
    raise

requests = None
display = LCDWingLite(board.I2C())
bme280 = adafruit_bme280.Adafruit_BME280_I2C(board.I2C())
clock = rtc.RTC()

def setup_wifi_if_needed():
    global requests
    if requests is None:
        display.print("     ")
        display.set_indicator(Indicator.WIFI)
        display.blink(3)
        wifi.radio.connect(secrets["ssid"], secrets["password"])
        pool = socketpool.SocketPool(wifi.radio)
        requests = adafruit_requests.Session(pool, ssl.create_default_context())
        display.blink(0)

def set_time():
    setup_wifi_if_needed()
    aio_username = secrets["aio_username"]
    aio_key = secrets["aio_key"]
    location = secrets.get("timezone", None)
    TIME_URL = f"https://io.adafruit.com/api/v2/{aio_username}/integrations/time/strftime?x-aio-key={aio_key}&tz={location}&fmt=%25Y-%25m-%25d+%25H%3A%25M%3A%25S"

    response = requests.get(TIME_URL)
    components = response.text.split(' ')

    (year, month, day) = components[0].split('-')
    (hour, minute, second) = components[1].split(':')
    clock.datetime = time.struct_time((int(year), int(month), int(day), int(hour), int(minute), int(second), 0, -1, -1))

def post_data(temperature, humidity, pressure, battery):
    setup_wifi_if_needed()
    aio_username = secrets["aio_username"]
    aio_key = secrets["aio_key"]
    io = IO_HTTP(aio_username, aio_key, requests)

    try:
        io.send_data("lcd-logger.temperature", temperature)
        io.send_data("lcd-logger.humidity", humidity)
        io.send_data("lcd-logger.pressure", pressure)
        io.send_data("lcd-logger.battery", battery)

    except Exception as e:  # pylint: disable=broad-except
        print(e)
        display.print("Error")
        go_to_sleep()

def go_to_sleep():
    # Clear all indicators except for the sleep indicator
    display.clear_indicator(Indicator.ALL)
    display.set_indicator(Indicator.MOON)

    # Shut down I2C power
    i2c_power = digitalio.DigitalInOut(board.I2C_POWER)
    i2c_power.switch_to_input()

    # Go to sleep
    time_alarm = alarm.time.TimeAlarm(monotonic_time=time.monotonic() + 60 - clock.datetime.tm_sec)
    alarm.exit_and_deep_sleep_until_alarms(time_alarm)

# Main loop begins here!

if alarm.wake_alarm is None:
    set_time()

# Get temperature in fahrenheit; for celsius, remove the conversion factor
temperature = bme280.temperature * (9 / 5) + 32

# At the top of the hour, upload data to adafruit.io
if clock.datetime.tm_min == 0 and clock.datetime.tm_hour != alarm.sleep_memory[0]:
    # stash the current hour in alarm.sleep_memory[0] so we don't double-log if the clock was fast
    alarm.sleep_memory[0] = clock.datetime.tm_hour
    # Read new sensor data
    humidity = bme280.relative_humidity
    pressure = bme280.pressure
    battery_voltage = LC709203F(board.I2C()).cell_voltage

    # Show the DATA indicator to indicate that we're transferring data
    display.set_indicator(Indicator.DATA)
    post_data(temperature, humidity, pressure, battery_voltage)
    set_time()
    display.clear_indicator(Indicator.DATA)

# Always update the temperature display
display.print("{:.1f}#F".format(temperature))

go_to_sleep()