Making a LED matrix took me way longer than expected. Things I might consider next time: mind the diameter of the wiring or they’ll burn and the 2gb sd-card lying around might not be big enough..
One of my long standing idea was to build a LED-Matrix, probably due to watching too much Knight Rider. With LED matrices being widely available and also inspired, again, by things I saw at the GPN18 I ordered a 64x64 LED display for a decoration of an upcoming event.
[image VL53L0X/20180528_193737.gif “the first test”]
Raspberry pi zero controlled LED matrix with a distance sensor that turns it off when no one is around.
Getting things done
Raspberry pi zero
- get headless raspbian lite and make bootable sd-card enable SSH (put an empty file named “ssh” on the sd card, like here
- to enable the wifi. I use a linux based os to access the file: /etc/wpa_supplicant/wpa_supplicant.conf. In this file include:
- put the sd-card in your raspberry and run
- connect over ssh from your computer (wifi should work)
- change password and enable I2C by sudo raspi-config
- install the H. Zeller git, as described here: https://learn.adafruit.com/matrix-led-sand/code
- install the latest java (for webserver): sudo apt-get install openjdk-9-jdk-headless (or 8 for a raspberry nano), jre is not enough for the webserver. I ended up using the oracle version: sudo apt-get install oracle-java8-jdk (supposedly faster? )
- I had problems with java and found a solution with this: You need to first remove ca-certificate-java found here:
sudo apt-get purge ca-certificate-java sudo apt-get install -f
- here I had to start all over since the old 2gb sd-card was full. The transfer did clearly not change the partition but at least I then knew how to backup (as for example described in detail here):
diskutil list sudo dd bs=1m if=/dev/disk2 | gzip > ~/Desktop/rpi-image.gz
I decided to use a time-of-flight distance sensor that uses a laser source like this one. I was actually able to visualize the laser point using a fullspectrum camera, which I thought was nice as a confirmation of the measuring angle (the left picture shows only a tiny source where intensity increases when moving the lens just parallel ).
3D printed parts
I modified an scad frame as described on thingiverse.
To code something without knowing the language (python in this case) took quite some time and still is quite unfinished although working: Check out the code if interested.