1. Banking API

    For another project (the shackbureau) we needed to convert banking numbers from the old German system to the European system. At first we used the webpage of a German bank but after their relaunch the form was removed.

    After some searching we found the data from the German federal bank ...

    Tagged as : oklab
  2. Particles sensor of opendata-stuttgart

    Tagged as : particels feinstaub oklab
  3. Voltage Regulator

    To use the ESP8266 and the PPD42NS together we need 5V and 3.3V.

    There are some ways to achieve this.

    First option

    Buy a LM1117.

    Second option

    I didn't have a LM1117, but got a LM317 and two resistors.

    The schema to build a voltage regulator with this ...

    Tagged as : arduino
  4. Imagegeneration for Kindle 4

    Task: Generate images displayable on a Kindle 4.

    Example code using Python and Pillow:

    # -*- coding: utf-8 -*-
    from PIL import Image, ImageDraw, ImageFont
    image = Image.new("P", (600,800), 255)
    # generate a 8 bit greyscale palette
    def palette():
      for i in range(0,256):
        yield i;yield i; yield i
    image ...
    Tagged as : linux kindle
  5. ESP8266 Learnings

    • reducing voltage with resistors can interfere with the PULLUP of your GPIO -> don't pullup
    • a 1€ USB powerplug is crap. you get a lot of interference on your analog signal (i.e. PPD42NS)
    • always cross-check with an oscilloscope. you may be surprised how bad your sensor signal is.

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