The Circuit Playground Express boards can run CircuitPython — a different approach to programming compared to Arduino sketches. In fact, CircuitPython comes factory pre-loaded on the Circuit Playground Express. If you’ve overwritten it with an Arduino sketch, or just want to learn the basics of setting up and using CircuitPython, this is explained in the Adafruit Circuit Playground Express Guide.
To use the code below, plug the Circuit Playground Express into USB…it should show up on your computer as a small flash drive…then edit the file “code.py” with your text editor of choice. Select and copy the code below and paste it into that file, entirely replacing its contents (don’t mix it in with lingering bits of old code). When you save the file, the code should start running almost immediately.
# SPDX-FileCopyrightText: 2018 Mikey Sklar for Adafruit Industries
#
# SPDX-License-Identifier: MIT
import time
import adafruit_CCS811
import board
import busio
import neopixel
# i2c interface for the gas sensor
i2c_bus = busio.I2C(board.SCL, board.SDA)
ccs = adafruit_CCS811.CCS811(i2c_bus)
# Three Different NeoPixel 8 LED Lengths for Output:
# 1 - Temperature - Circuit Playground Built-In LEDs
# 2 - Total Volatile Organic Compounds [strip]
# 3 - Co2 Output - NeoPixel [strip]
num_leds = 8
temperature_pix = neopixel.NeoPixel(board.NEOPIXEL, num_leds, brightness=.1)
tvoc_pix = neopixel.NeoPixel(board.A1, num_leds, bpp=4, brightness=.1)
co2_pix = neopixel.NeoPixel(board.A2, num_leds, bpp=4, brightness=.1)
led_draw = .05 # delay for LED pixel turn on/off
# wait for the sensor to be ready and calibrate the thermistor
while not ccs.data_ready:
pass
temp = ccs.temperature
ccs.temp_offset = temp - 25.0
def clear_pix(delay):
# clear all LEDs for breathing effect
for i in range(0, num_leds):
temperature_pix[i] = (0, 0, 0)
co2_pix[i] = (0, 0, 0, 0)
tvoc_pix[i] = (0, 0, 0, 0)
time.sleep(delay)
def co2_led_meter():
# Show Carbon Dioxide on a NeoPixel Strip
co2_floor = 400
co2_ceiling = 8192
# Map CO2 range to 8 LED NeoPixel Stick
co2_range = co2_ceiling - co2_floor
co2_led_steps = co2_range / num_leds
co2_leds = int((ccs.eCO2 - co2_floor) / co2_led_steps)
# Insert Colors
for i in range(0, (co2_leds - 1)):
co2_pix[i] = (255, 0, 255, 0)
time.sleep(led_draw)
def tvoc_led_meter():
# Show Total Volatile Organic Compounds on a NeoPixel Strip
tvoc_floor = 0
tvoc_ceiling = 1187
# Map CO2 range to 8 LED NeoPixel Stick
tvoc_range = tvoc_ceiling - tvoc_floor
tvoc_led_steps = tvoc_range / num_leds
tvoc_leds = int(ccs.TVOC / tvoc_led_steps)
# Insert Colors
for i in range(0, (tvoc_leds - 1)):
tvoc_pix[i] = (0, 0, 255, 0)
time.sleep(led_draw)
def temp_led_meter():
# Show Temperature on Circuit Playground built-in NeoPixels
temp_floor = 23
temp_ceiling = 36
# Map temperature range to 8 LEDs on Circuit Playground
temp_range = temp_ceiling - temp_floor
temp_led_steps = temp_range / num_leds
temp_leds = int((ccs.temperature - temp_floor) / temp_led_steps)
# Insert Colors
for i in range(0, (temp_leds - 1)):
temperature_pix[i] = (255, 255, 0)
time.sleep(led_draw)
while True:
# print to console
# - co2
# - total voltatile organic compounds
# - temperature in celsius
print("CO2: ", ccs.eCO2, " TVOC:", ccs.TVOC, " temp:", ccs.temperature)
co2_led_meter()
tvoc_led_meter()
temp_led_meter()
time.sleep(.5)
clear_pix(led_draw)
Page last edited January 20, 2025
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