Pressure balloon demo with BMP280 on Feather nRF52840 Sense

pressure_to_colour.py

# Simple Pressure to color demo.

import time
import board
import digitalio
import neopixel
import adafruit_bmp280

# Used for pressure.
bmp280 = adafruit_bmp280.Adafruit_BMP280_I2C(board.I2C())

# Feather nRF52840 Sense with single NeoPixel.
pin_pixels = board.NEOPIXEL
num_pixels = 1
pixels = neopixel.NeoPixel(pin_pixels, num_pixels, brightness=1, auto_write=False)
pixels.fill( (0,0,255) )
pixels.show()
time.sleep(1)

ratio = 0.0
baro_range = 0.0
baro_min = bmp280.pressure
baro_max = baro_min + 1.0 # Avoid flickering between green and red at startup

while True:
    baro_now =  bmp280.pressure
    if baro_now > baro_max:
        baro_max = baro_now
#        print("MAX reached and adjusted")
    if baro_now < baro_min:
        baro_min = baro_now
#        print("min reached and adjusted")
    baro_range=baro_max-baro_min
    baro_zero=baro_now-baro_min
    ratio = (baro_zero*100.0) / baro_range

    colour = ratio * 255 / 100
    colour_inv = 255 - colour
    color = (colour, colour_inv, 0)
    pixels.fill( color ) # Green to Red depending on pressure
    pixels.show()