[Adrian] and [Obelix] wanted to have an easy way to know when to expect the public transportation, so they hacked an LED dot matrix display to show arrival times for stops near their dorm.
They found the display on Ebay with a defective controller which they replaced with an ATmega328p. They connected the display to the internet by adding a small TP-Link MR3020 router and connecting it to the ATmega328p via a serial line. Their local transportation office’s web page is polled to gather wait times for the stops of interest. All rendering of the final image to display to the dot matrix display is done on their PC, which then gets pushed through to the MR3020, which in turn pushes it out to the ATmega328p for final display.
[Adrian] and [Obelix] warn about setting proper watchdog timers on the display driver to make sure bugs in the controller don’t fry the dot matrix elements. Their ATmega328p dot matrix driver code can be found on [Adrian]’s GitHub page.
Check out a video of the display in action after the jump.
Continue reading “Public Transportation Display”
Seen at the center of this image is a TP-Link TL-MR3020 which is basically a TL-WR703N wireless router with a few extra LEDs. We’ve seen a lot of projects using this hardware and that’s because it’s cheap and ripe for hacking. The devices can run OpenWRT, a Linux distro for routers that greatly extends the functionality when compared to the stock firmware. Now a couple of members of Shackspace — a hackerspace in Stuttgart, Germany — have written a script that automatically generates specialized firmware for the router. That link goes to their wiki page about the script, but you may find this overview post to be an easier read.
The concept is that gathering specialized hacks into easy to flash packages does away with a lot of configuration headaches. For example, if you just want to play around with an NFC reader for a day-long event you can connect hardware like what is seen above and use the NFC-gate option of the script to flash firmware meant to drive it. So far there’s also support for streaming a USB webcam, serving as a USB network bridge, and a few others. But the whole point of this is to make it simple to roll new firmware mods into the script that make it easy to preserve the work for use at a later time.