crwdns312214:0crwdne312214:0

1from microbit import *
2display.show('L')
3
4LIGHT = 114  # <<< Enter your 'measured' reading here
5WATTS = 1000  # <<< Enter your bulb wattage here
6COSTPERKWH = 0.18  # <<< Enter unit electricity cost here
7
8HYSTERESIS = 8
9LIGHT -= (HYSTERESIS/2)
10DARK = LIGHT - HYSTERESIS
11ON_IMAGE = Image('99999:99999:99999:99999:99999')
12OFF_IMAGE = Image('00000:00000:00900:00000:00000')
13timing = False
14start_time = 0
15total_time = 0
16reading = display.read_light_level()
17sleep(1000)
18
19def calc_cost(m):
20    # Calculate cost of electricity for this number of mins
21    kw = WATTS / 1000.0  # answer as a decimal
22    hours = m / 60.0  # answer as a decimal
23    kwh = kw * hours
24    cost = kwh * COSTPERKWH
25    return cost  # as pounds and pence
26    
27def show_number(n):
28    # Scroll number as 3 decimal places
29    display.scroll("%.3f" % n)
30
31while True:
32    reading = display.read_light_level()
33    if reading < DARK:
34        if timing:
35            # it has just gone dark, update timer for 'on' time
36            end_time = running_time()
37            total_time += (end_time - start_time)
38            timing = False
39        
40    elif reading >= LIGHT:
41        if not timing:
42            # it has just gone light, start the timer
43            start_time = running_time()
44            timing = True
45        
46    if button_b.was_pressed():
47        # calculate and display cumulative cost in pounds and pence
48        minutes = total_time / 60000
49        if timing:
50            # adjust live for current ON time
51            minutes += (running_time() - start_time) / 60000
52        display.clear()
53        show_number(calc_cost(minutes))
54        sleep(500)
55
56    # update the display with the ON/OFF state
57    if timing:
58        display.show(ON_IMAGE)
59    else:
60        display.show(OFF_IMAGE)
61    sleep(1000)
62
63