In this tutorial series, you will learn how to use a Raspberry Pi Zero to display the current temperature on a ws2812b 32x8 LED matrix in Python.

In Part 4, we will retrieve data from the OpenWeather API, display the temperature and weather condition glyph, and set up a cron job to trigger every hour.

Display temperature on LED matrix

Integrate with the OpenWeather API.

  1. Sign up and subscribe to the Free API to obtain an API key.
  2. Update to retrieve data from the API.
  3. For more information, please refer to the API documentation.
import math import requests from lib.pixels import * from lib.sprite_painter import * from coordinate.num_coordinate import numbers from coordinate.glyph_coordinate import weather API_KEY = 'Put your OpenWeather API key here' ## Your preferred location LAT = Your latitude LON = Your longitude ## I exclude all of this except 'current', please check API document. PART = 'minutely,hourly,daily,alerts' url = f'{LAT}&lon={LON}&exclude={PART}&appid={API_KEY}&units=metric' def get_weather(): """ Request weather data. Return current temperature and current weather condition """ response = requests.get(url) data = response.json() temp_celsius = data['current']['temp'] weather_condition = data['current']['weather'][0]['main'] return temp_celsius, weather_condition def draw_temp(pixels, temp_celsius): """ Draw temperature, degree symbol, and minus sign if necessary. """ ## the API return temperature in float format. So, I converted to string before using it. temp_celsius = str(math.floor(temp_celsius)) # if temperature is one digit or two digit I want to add space in front of it. if len(temp_celsius) == 1 or len(temp_celsius) == 2: temp_celsius = ' ' + temp_celsius temp_celsius = temp_celsius + 'c' for i in range(0, len(temp_celsius)): sprite = MonochromeSprite(height = 8, width = 6, pixels = numbers[temp_celsius[i]]) # Adjust a place to start drawing the first sprite. The next sprite # will be positioned after the previous one. position_x = i * 6 + (-1 if len(temp_celsius)-1 == i else 0) position_y = 0 ## the starting point of y axis is always 0 for 32x8 matrix draw_monochrome_sprite(pixels, sprite, (position_x, position_y), Color(0, 0, 200)) def draw_wcondition(pixels, w_condition): """ Draw colorful weather condition glyph. """ ## You can check the API documentation. If you are using OpenWeather like me, ## you should have the same list below. etc_glyph_set = {'Mist', 'Smoke', 'Haze', 'Dust', 'Fog', 'Sand', 'Ash', 'Squall'} w_condition = 'Etc' if w_condition in etc_glyph_set else w_condition sprite = ColorfulSprite( height=8, width=12, layers=weather[w_condition] ) ## For the glyphs of weather condition, I set started location of x axis at position 20. ## The initial color will be overide at draw colorful sprite method. position_x = 20 position_y = 0 draw_colorful_sprite(pixels, sprite, (position_x, position_y), Color(255, 0, 0)) if __name__ == '__main__': pixels: Pixels = Pixels() temp_celsius, weather_condition = get_weather() ## temp_celsius, weather_condition = ['-8', 'Snow'] ## Clean up the display before draw the new one pixels.clear() draw_temp(pixels, temp_celsius) draw_wcondition(pixels, weather_condition)

Adjust the design as you prefer:

  1. I want to add some space in front of the temperature if it is a single digit number (0 - 9 only), followed by a ‘c’ symbol. To achieve this, I need to add ‘ ‘: [] in coordinate/
Display temperature before and after adjust space

Set a cron job/trigger to run every hour:

  1. Open the crontab file by typing crontab -e in the terminal. The crontab file contains commands that will automatically execute at the specified time defined by the first five fields of each command. Read more about crontab here.
  2. Add the following line to the crontab file: 0 * * * * sudo python ~/display/
  3. To retrieve new temperature data every hour, we need to set up a cron job that triggers at the specified interval.

Now we are finished!
Good job! See you in the next project 🥳