An illustrated history of Project BlipBox.
It started back in 2008 with an idea born out of an attempt to make a full-colour, Arduino-based Monome. Inspired and helped along by the Arduino maker community, with little actual knowledge but much enthusiasm, our crazy designs started to take an physical form.
The first strip-board prototype was made with a TLC4950 LED driver, multiplexed with a 4017 CMOS johnson counter clocked to the former’s BLANK pin. This very clever arrangement meant that no extra pins were needed for the multiplexing. The pin headers plugged into an arduino which was also connected to a 5inch resistive touch screen. The back of this board has some pretty insane air-wires running all across it. As it turned out the multiplexing part was a bit too clever for it’s own good – the CMOS counter wasn’t really capable of sourcing enough current to drive 16 LEDs at the same time. Apart from the 4017 being replaced with direct driven transistors, the basic design hasn’t changed much!
The next prototype used proper LED modules, and was made as an Arduino shield. The Arduino was sandwiched between the board and the modules which plugged in on top. A button and pot were added to extend the tweaking possibilities. It all fitted into a white plastic case and made it into a couple of videos.
The next step was to figure out how to use PCB design software and create a custom board. A number of revisions were made to try to eliminate problems with flicker and general instability. A certain prototype would at one point work perfectly, then the next day it would have all sorts of problems: LED rows flickering like crazy, or not showing at all. Even the way you picked up a board would change how it behaved. A troubleshooting nightmare had begun.
This is where, somewhat belatedly, the breadboards and arduino came in handy. However, the breadboarded design didn’t have any of the problems of the PCB’s. With the exact same components, it just worked. Perfectly.
To make sure that the LEDs could source enough current we started using discrete transistors to power the rows. This, plus a handy capacitor on the TLC5940 driver chip, finally put an end to our phantom flicker problems. This is BlipBox PCB version 9, with the USB, MIDI and power regulator extension board.