pimoroni-pico/micropython/examples/pico_explorer/thermometer.py

# This example takes the temperature from the Pico's onboard temperature sensor, and displays it on Pico Explorer, along with a little pixelly graph.
# It's based on the thermometer example in the "Getting Started with MicroPython on the Raspberry Pi Pico" book, which is a great read if you're a beginner!

import st7789
import machine
import utime

# Pico Explorer boilerplate
display = st7789.ST7789(st7789.DISPLAY_PICO_EXPLORER, rotate=0)
display.set_palette_mode(st7789.PALETTE_USER)
display.set_backlight(1.0)

WIDTH, HEIGHT = display.get_bounds()

# reads from Pico's temp sensor and converts it into a more manageable number
sensor_temp = machine.ADC(4)
conversion_factor = 3.3 / (65535)

BLACK = display.create_pen(0, 0, 0)
WHITE = display.create_pen(255, 255, 255)
RED = display.create_pen(255, 0, 0)
GREEN = display.create_pen(0, 255, 0)
BLUE = display.create_pen(0, 0, 255)

i = 0

while True:
    # the following two lines do some maths to convert the number from the temp sensor into celsius
    reading = sensor_temp.read_u16() * conversion_factor
    temperature = round(27 - (reading - 0.706) / 0.001721)

    # this if statement clears the display once the graph reaches the right hand side of the display
    if i >= WIDTH + 1:
        i = 0
        display.set_pen(BLACK)
        display.clear()

    # chooses a pen colour based on the temperature
    display.set_pen(GREEN)
    if temperature > 20:
        display.set_pen(RED)
    if temperature < 13:
        display.set_pen(BLUE)

    # draws the reading as a tall, thin rectangle
    display.rectangle(i, HEIGHT - (temperature * 6), 6, HEIGHT)

    # draws a white background for the text
    display.set_pen(WHITE)
    display.rectangle(1, 1, 65, 33)

    # writes the reading as text in the white rectangle
    display.set_pen(BLACK)
    display.text("{:.0f}".format(temperature) + "c", 3, 3, 0, 4)

    # time to update the display
    display.update()

    # waits for 5 seconds
    utime.sleep(5)

    # the next tall thin rectangle needs to be drawn 6 pixels to the right of the last one
    i += 6