CO2 monitor using Pimoroni Tufty 2040 + Adafruit SCD-40, MicroPython 1.20.3

main.py

# https://github.com/pimoroni/pimoroni-pico/blob/main/micropython/examples/tufty2040/main.py
# https://github.com/pimoroni/pimoroni-pico/blob/main/micropython/examples/tufty2040/pride_badge.py
# https://github.com/pimoroni/pimoroni-pico/blob/main/micropython/examples/breakout_scd41/scd41_demo.py

from picographics import PicoGraphics, DISPLAY_TUFTY_2040, PEN_RGB332
import time, math, random, gc
from pimoroni import Button, BREAKOUT_GARDEN_I2C_PINS
import breakout_scd41
from pimoroni_i2c import PimoroniI2C

i2c = PimoroniI2C(**BREAKOUT_GARDEN_I2C_PINS)
breakout_scd41.init(i2c)
breakout_scd41.start()

display = PicoGraphics(display=DISPLAY_TUFTY_2040, pen_type=PEN_RGB332, rotate=180)

# convert a hue, saturation, and value into rgb values
def hsv_to_rgb(h, s, v, co2):
    if s == 0.0: return v, v, v
    i = int(h * 6.0)  
    f = (h * 6.0) - i
    p, q, t = v * (1.0 - s), v * (1.0 - s * f), v * (1.0 - s * (1.0 - f))
    v, t, p, q = int(v * 255), int(t * 255), int(p * 255), int(q * 255)
    i = i % 6
    #if i == 0: return v, t, p # yellows oranges and reds
    #if i == 1: return q, v, p # greens and yellow
    #if i == 2: return p, v, t # greens and blues
    #if i == 3: return p, q, v # blues
    #if i == 4: return t, p, v # pinkish purply blues
    #if i == 5: return v, p, q # pinks and reds
    if co2 < 600:
        return p, v, t
    elif co2 >= 800:
        return v, t, p
    else:
        return q, v, p


button_up = Button(22, invert=False)
button_down = Button(6, invert=False)

BACKLIGHT = 1.0
display.set_backlight(BACKLIGHT)

WIDTH, HEIGHT = display.get_bounds()

WHITE = display.create_pen(255, 255, 255)
BLACK = display.create_pen(0, 0, 0)

NAME = "???"
co2 = 600

while True:
    t = time.ticks_ms() / 1000.0
    
    if button_up.read():
        BACKLIGHT = BACKLIGHT + 0.1
        if BACKLIGHT > 1.0:
            BACKLIGHT = 1.0

    if button_down.read():
        BACKLIGHT = BACKLIGHT - 0.1
        if BACKLIGHT < 0.3:
            BACKLIGHT = 0.3
       
    display.set_pen(display.create_pen(50, 50, 70))
    display.clear()
    
    # Change details here! Works best with a short, one word name
    if breakout_scd41.ready():
        co2, temperature, humidity = breakout_scd41.measure()
        NAME=str(int(co2))

    grid_size = 40
    for y in range(0, HEIGHT / grid_size):
        for x in range(0, WIDTH / grid_size):
            h = x + y + int(t * 5)
            h = h / 50.0
            r, g, b = hsv_to_rgb(h, .5, 1, co2)
            
            display.set_pen(display.create_pen(r, g, b))
            display.rectangle(x * grid_size, y * grid_size, grid_size, grid_size)

    # Change the colour of the text (swapping these works better on a light background)
    TEXT_COLOUR = BLACK
    DROP_SHADOW_COLOUR = WHITE

    # Set a starting scale for text size.
    # This is intentionally bigger than will fit on the screen, we'll shrink it to fit.
    name_size = 20

    # These loops adjust the scale of the text until it fits on the screen
    while True:
        display.set_font("bitmap8")
        name_length = display.measure_text(NAME, name_size)
        if name_length >= WIDTH - 20:
            name_size -= 1
        else:
            # comment out this section if you hate drop shadow
            DROP_SHADOW_OFFSET = 5
            display.set_pen(DROP_SHADOW_COLOUR)
            display.text(NAME, int((WIDTH - name_length) / 2 + 10) - DROP_SHADOW_OFFSET, 10 + DROP_SHADOW_OFFSET, WIDTH, name_size)

            # draw name and stop looping
            display.set_pen(TEXT_COLOUR)
            display.text(NAME, int((WIDTH - name_length) / 2 + 10), 10, WIDTH, name_size)
            break

    display.set_backlight(BACKLIGHT)

    display.update()