Using the Enviro pHAT to calculate the average lux in the room, and turn on some lights if it gets too dark

pi-lluminate-test.py

#!/usr/bin/env python

import sys
import requests
import time
import datetime
import os
from envirophat import light

# Get the current time
def whats_the_time():
    now = datetime.datetime.now()
    return (now.strftime("%H:%M:%S"))

# The function to turn off the lights. Sends a webhook to IFTTT which
# triggers Hue.

def turn_off():
    requests.post("https://maker.ifttt.com/trigger/{TRIGGER_WORD}/with/key/{TOKEN_GOES_HERE}")
    print("Lights off!")
    sys.stdout.flush()

# The function to turn on the lights. Sends a webhook to IFTTT which                   
# triggers Hue.

def turn_on():
    requests.post("https://maker.ifttt.com/trigger/{TRIGGER_WORD}/with/key/{TOKEN_GOES_HERE}")
    print("Lights on!")
    sys.stdout.flush()

# Check the light level and determine whether the lights need to 
# be turned on or off.

def average_lux():
    # Variables for calculating the average lux levels
    start_time = time.time()
    curr_time = time.time()
    collect_light_time = 15 # Maybe use 60?
    collect_light_data = []

    # Calculate the average lux level over 15 seconds
    print("Calculating average light level...")
    while curr_time - start_time < collect_light_time:
	curr_time = time.time()
	avg = light.light()
	collect_light_data.append(avg)
	time.sleep(1)
    average_light = sum(collect_light_data[-10:]) / 10.0
    #average_light = int(average_light_raw)
    now = whats_the_time()
    print("{} {} {} {} {} {} {} {}.".format("Average over", collect_light_time, "seconds", "is:", average_light, "lux.", "Last checked at", now))
    sys.stdout.flush()
    print("{} {} {} {}.".format("Waiting", "45", "seconds", "before trying again"))
    sys.stdout.flush()
    return average_light

try:
    # Local variables.
    state = 0	# Sets the state for the lights.
    low = 260	# Low value for light level (lux).
    high = 300	# High value for light level (lux).
    period = 45	# Delay, in seconds, between calls.
    while True:
	# Get the average lux level first,
	room_light = average_lux()
	# Now check if the room is dark enough then turn on the lights.
	if room_light < low and state != 1:
	    turn_on()
	    state = 1
	# Or if it is bright enough, turn off the lights.
	elif room_light > high and state == 1:
	    turn_off()
	    state = 0
	time.sleep(period)
except KeyboardInterrupt:
    pass

Pi-lluminate.md

Pi-lluminate the room

This is an attempt at a Python script to make use of Pimoroni's Enviro pHAT to calculate the average light level (lux) in a room, and to trigger an action if the lux drops below a pre-determined threshold (in this case, send a webhook command to turn on some Philips Hue lights).

Enviro pHAT average lux calculation

I "borrowed" some of the code used in Pimoroni's BME680 Breakout Board to calculate the average lux level. The idea being that the Enviro pHAT captures the lux for 15 seconds, then calculates the average reading that is then used to trigger the action.

Webhooks

For simplicity, I'm using IFTTT's Maker channel to use webhooks. These webhooks link to an IFTTT applet that triggers a Philips Hue bulb at home based on the parameters passed.