Live Energy Monitor

energy.py

#!/usr/bin/env python3

import math
import time
import unicornhathd
import urllib.request
import json

# Rotate the display to the desired orientation
unicornhathd.rotation(-90)
unicornhathd.brightness(1.0)

# Colours for positive and negative measurements
bar_colour_down = [64, 0, 128]
bar_colour_up = [0, 128, 0]

# P1 Meter API
url = "http://192.168.0.221/api/v1/data"

# Store measurements
measurements = []
leds = []

# Get the data from the API and parse the desired value
def getDataFromP1(url):
    response = urllib.request.urlopen(url)
    data = response.read()
    values = json.loads(data)

    return values["active_power_w"]

# Store the measurements in an array
def updateMeasurements(array):
    if len(array) >= 16:
        array.pop(0)

    array.append(getDataFromP1(url))

# Convert the measurements to number of LEDs to light up
def transformMeasurements(arrayIn, arrayOut):
    arrayOut.clear()

    for element in arrayIn:
        arrayOut.append(math.ceil(element/250))
        
# Update the Unicorn HAT
def updateDisplay(array):
    unicornhathd.clear()

    offset = 0
    column = 0

    for height in array:
        # Respect the boundaries of the display
        if height > 8:
            height = 8
        if height < -8:
            height = -8

        for pixel in range(abs(height)):
            # Use the top half of the display for positive measurements
            if height > 0:
                offset = 8
                r = bar_colour_down[0]
                g = bar_colour_down[1]
                b = bar_colour_down[2]

                unicornhathd.set_pixel(column, offset + pixel, r, g, b)

            # Use the bottom half of the display for negative measurements
            if height < 0:
                offset = 7
                r = bar_colour_up[0]
                g = bar_colour_up[1]
                b = bar_colour_up[2]

                unicornhathd.set_pixel(column, offset - pixel, r, g, b)

        column += 1

    unicornhathd.show()

# Continuously retrieve measurements and update the display
while True:
    updateMeasurements(measurements)
    transformMeasurements(measurements, leds)
    updateDisplay(leds)

    time.sleep(1)