Rebraining An LED Marquee With A SparkCore

Wires? Where this LED scroller is going we don’t need wires. Well, except for power but everything needs power. The 90×7 LED marquee hangs over the entrance to NYC Resistor’s laser cutter room. Thanks to a Spark Core and a bit of work from [Trammell Hudson], the sign is working and attached to the network.

The original unit called for an RS485 connection for input. Other than that there wasn’t really a reason it had been collecting dust. Closer inspection of the internals proved that the display is driven exactly as you would expect: transistors for the rows and shift registers for the columns. Well, actually the columns are split into separate shift registers for the even and odd but that doesn’t complicate things too much. GPIO takes the seven row-driving transistors, two shift register clocks, data, latch, and enable for a total of twelve pins.

The Spark Core completely replaces theĀ Atmel 80C32X2 and its RTC by pinging the network for UTC time synchronization once per day.

[via NYC Resistor]

6 thoughts on “Rebraining An LED Marquee With A SparkCore

  1. Just last month I got one of these working for our hackerspace in Nashua.

    The input power connector wanted 15v AC, but a DC wall wart will work just fine (consider the bridge rectifier for a sec and you’ll see why).

    I then connected a USB->TTL serial cable directly to the microcontroller Rx/Tx inputs, completely bypassing the RS485 nonsense.

    Now we have an older marquee sign modified to work off of USB, which can be controlled by any computer.

    Adding a USB->TTL serial cable might be a bit easier than replacing the internal CPU.

  2. Rs485 was for a LONG cable to feed data. Not nonsense if the display was located 500 feet away from the data source. Try sending high baud rate data over rs232 that far it cannot be done.

    1. Oh, heh…it can be done – not that it’s a good idea. Back in the day I had many 1000 to 2000 foot RS232 runs to connect terminals to a PDP11/70. They worked fine at 9600 baud. We did find that, if you had one that didn’t have a terminal plugged into it, it would collect noise that looked like a steady stream of charactes and interrupt the CPU continuously. We had to either unplug unused lines at the computer end, or plug “terminators” into the other end, with pins 2 and 3 jumpered to 7.

Leave a Reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.