Sorry if this sounds like a stupid question but why not use an NRF and play with the BT TX power? Is it because it wouldnt work for the games where people had to scan something in close proximity? (which i guess would be messy with BT) Also why do u use an led driver instead of driving the LEDs with the gpios? And holy shit u made 28,600pcs. Impressive work!
I am not Joe, but these are not stupid questions either. I might be able to shed some light on these choices until Joe responds. You may already know this, but LED drivers allow many LEDs to only occupy one pin on your controller. Why not use a driver if you can? As far as using bluetooth and nfc stuff. This was what plenty of people early in the conference thought the badges might be using. So the choice not use old tech that hackers have already seen and are expecting was intentional. Aside from adding to the challenge of hacking the badge, this is technology being more adopted in the wearable landscape and the chip Joe used at the time, not too many engineers previously had an arbitrary chance to play with as even its documentation came at a price and NDA that summer. Like Joe mentions in the video, a pretty cool and common use right now for NFMI is in combo with bluetooth! If you have a bluetooth device that's actually a pair of devices (like earbuds), you have one of the devices connect with a client over bluetooth, and the two earbuds communicate with each other via magnetic induction. tl;dr NFMI was a newer, less common curve ball to throw at dc hacker kidz.
