A while back, [limpfish] bought a few four-digit seven-segment displays from a seller on eBay. A month or two later, thirty displays ended up in [limpfish]’s mailbox. Instead of using the one or two displays he thought he ordered, [limpfish] decided to do something very cool with these bits of seven-segment displays. He’s controlling all of them at once.
[limpfish]’s usual method of controlling a lot of LEDs is the MAX7219 LED driver. This chip can easily — and cheaply — control eight common cathode seven segment displays. There’s a problem with this plan, though: the LEDs received from eBay are common anode. That’s actually not a problem, because with a little effort and even more thinking [limpfish] got these displays to work with the MAX7219 driver chip.
With chips in hand, [limpfish] designed a small breakout board for the MAX7219 and two common anode 4×7 segment displays. These displays can be daisy chained, and connecting them all together results in a very weird but very cool visualization.
[limpfish] is treating this display as a bitmap display, which means it’s demo time. You can check out a 1337 01d skool demo playing on this 840-segment display in the video below.
So basically a tiny version of the Digit_Grid display with 4096 segments then…. :-)
http://www.skot9000.com/digitgrid/
But still nice….
Very cool. Now for an encore let’s see some PWM! ;)
Article says: “control eight common cathode seven segment displays”
vs website: “Here’s my final setup controlling 8 common anode digits :”
One display is four digits, so one chip can drive two displays but not eight.
Eh? 7 segs are commonly produced in single or 4x packages. Both are displays. Just that one contains 4 digits the other 1 digit. Either way, a single max7219 can control 8 digits, either packaged in a single digit ‘display’ or packaged as 4x ‘display’.
Lovely
It’s far more mesmerizing than I expected. Well done. I’d like to see a music visualizer built from it.
I just want to include this link to a previous pertinent hackaday article: http://hackaday.com/2013/11/21/7-segment-display-matrix-visualizes-more-than-numbers/
I liked the one before that one https://hackaday.com/2012/03/30/display-made-out-of-hundreds-of-seven-segment-lcds/ saw it at maker faire that year too.