Controlling the LEDs with a 74HC595 chip

I finally got the 74HC595 chips and decided to do a dry run on a breadboard. I used the schematic I made earlier with Fritzing and just rebuilt it, with a couple of LEDs on every chip. I used the code from this blog as a base and it worked on the first try. Now I have to adapt this code for my purposes.

Don’t panic, the test setup looks worse than it is đŸ™‚

Working on the front plate

I started my second try on the front plate. Printing directly on the card board didn’t work out that well, so this time I printed it mirror inverted on a DIN A3 paper (the same size as the card board) and used spray glue to attach it to the card board. Then I used a crafting knife to cut out the characters, as before. This turns out to work pretty well, I guess the paper gives the card board even a little more stability.

Nevertheless this is a hell of work, the next time I’m doing something like this I have to come up with a better Idea for the front plate.

Thoughts on connecting the LEDs

This is a summary of some thoughts I had on connecting the LEDs to the Arduino. When I read about charlieplexing I was amazed how many LEDs I could control with so few pins on the Arduino. Then I realized the downside of this technique: Essentially I can only light a single LED at a given time. Sure, there are a couple that can be lit simultaneously when they don’t share any pins, but setting those up would be a nightmare. So I started to group the words. Which words have to be lit when? Continue reading Thoughts on connecting the LEDs

Arduino and the DS18B20 temperature sensor

So, this is the reason I started with an Arduino in the first place. In summer 2010 I ordered an Arduino and a DS18B20 temperature sensor because I wanted to monitor the water temperature in my aquarium in the summer and have the Arduino start fans if needed. My flat is directly below the roof and gets quite hot.

But I never figured out how to read the temperature from the sensor, every tutorial I followed, every code snippet I found showed either nothing at all or ridiculously wrong temperatures. Nevertheless, I just decided to try it again, wired it up and the third code snippet I tried worked. Of course, it’s the sample code right on the Arduino Playground

A DS18B20 temperature sensor wired up to an Arduino Duemilanove

Continue reading Arduino and the DS18B20 temperature sensor

Starting with the front plate

Today I was rummaging through a crafts store and found some dark card board and translucent paper. The paper is available in different colors, so I can customize the color of the words to my liking. I cut some rough letters out of the card board and placed the translucent paper behind it. Continue reading Starting with the front plate

Multimeter DT9205A

So, it finally arrived. I guess two weeks isn’t all that bad a delivery time from Hong Kong to Germany. My first impression after unwrapping it is … well, you get what you pay for. The workmanship is lousy, at least regarding the rubber cover. But hell, it was only 8.59 € including shipping costs. Continue reading Multimeter DT9205A