Public Transportation Display

display_cropped

[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.

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Reverse engineering a plasma dot matrix display

A while back, [DragonMinded] picked up a bunch of old arcade and pinball parts from a guy on Craigslist. These parts sat around for a while until a really neat plasma dot matrix display was found in the corner of a box in his garage. Doing the only reasonable thing, [DragonMinded] figured out how to interface this ancient display with a microcontroller.

After extensive Internet research on his display, [DragonMinded] could only find a one page datasheet for his APD-128G064A-1 display. Luckily, this datasheet had voltage requirements, and since the display only had six input pins he could probe the circuit to see what goes where.

After generating a crude schematic, [DragonMinded] prototyped a driver circuit with an Arduino. When the function of each pin was discovered, the Arduino libraries were discarded and replaced with raw register access.

It was a fair amount of work, but [DragonMinded] eventually got to the point where he could draw anything he wanted on the screen. Next on the to-do list is turning it into a terminal or Twitter machine, as with all good display hacks.