Continuation of a Theme

A project log for Pixel Badge 2 : Dark Pixel

A WS2812S conference badge

blinkingthingblinkingthing 10/06/2019 at 17:460 Comments

Pixel Badge 2 : Dark Pixel

Clockwise from top left. Protoboard, Cardboard v1 and v2, followed by v2.2 and v2.1 of Pixel Badge 2 : Dark Pixel
I wasn't finished with this whole pixel pcb idea after Defcon 27 so I'm continuing to develop it. 

A huge chunk of inspiration for part of this project came from Mohit Bhoite's brass rod electronic sculptures. This is where I began my prototyping. I ordered some brass tube from K&S metals per Mohit's suggestion and attempted to test it's solder-ability and continuity on a protoboard.


After I confirmed that the basic idea would work, I made my first cardboard badge prototype. I was in the middle of reading Adam Savage's "Every Tools a Hammer" and it may have inspired me to work with cardboard before jumping directly into KiCad and ordering PCBs. 

I started with an SVG of the shitty pixel SAO I made last year, just blown up in size to around 100mm square. I quickly started to come up with a list of changes I wanted to make to the overall design as well as the size. 

After the first cardboard badge, I started to work in KiCad and made a rough design and printed it out 1:1, and pasted it to another piece of cardboard for a second test. This 2nd prototype was used for testing the lengths of brass rod I would need for the bond-wires. 


I moved on to ordering a PCB prototype after being satisfied with the size of the board and feasibility of including brass tubing. Something new to me on this board was getting custom size holes drilled that would accept the brass tube. The brass tube is 1.5mm in diameter so I used 1.7mm holes in hopes of having enough clearance for an easy but solid fit. I completely screwed this up in KiCad by making the pad on the hole's footprint 1.7mm wide, but the hole that was to be drilled got left at it's default setting. Lesson learned ;)

With the holes not being wide enough to accept the brass pipe, I ended up soldering directly to the face of the PCB with copious amounts of solder. In addition to looking terrible, this reduced the number of unique touch inputs I could play with because some of the brass rods were now sharing an electrical connection via the larger copper pads on the front of the PCB. This was disappointing but I was still able to test some ideas and make some progress so I suppose it was still a success.


I'm now on the 2nd version of the dark pixel board and this time I got the hole drill sizes correct. I've also migrated all the circuitry from the hornbill dev board onto my badge in hopes that I will be able to utilize the lipo charger and USB to UART. I've yet to receive all the components so I haven't been able to fire one up. 

That's all for now, the next update will come in about 2 weeks when I get  the rest of the parts for v2.2.