I don't know how I came up with this idea. I just thought, it would be neat to have an addon nametag. An addon that's a little bit less shit. And I was planning on getting some accelerometers for the other badge project. Why not make a nametag where the name is always upright?
So here it is.
Another reason for making this is that I want to make a kickass WP badge for DEF CON and have no money. WP doesn't sell badges. So I'm doing this as a project under my own name to raise money for the WP badge project at DC28.
The result is pretty neat. The nametag has several selectable fonts and LED color modes, and will show your name in various configurations - including having the letters always upright relative to the ground.
The MCU selection was simple: I got a deal on some EFM8UB20F32G-A-QFP32. These are C8051 core MCUs with USB. Roughly guessing space used by fonts and features, I figured it would be tough to make everything fit but still possible. Turns out that with all the fonts I wanted and the abstractions in the code to make things border on readable and maintainable that this wasn't going to be enough. Thankfully there is a 64K version of this micro available but at full price... now with the code mostly written, I went ahead and upgraded.
I hadn't worked with an 8051 before but my badge designs will often use new parts or systems so that I can use them as an opportunity to learn. In this case, the micro and the rotation code were the things to learn.
USB support is helpful for firmware updates or possibly other features. The built in LDO means less components to be powered by USB. I was able to use a dual P channel FET and a diode to select power from USB or addon power and also prevent back-powering the USB connector. It's really a neat design with this micro.
What does "GAT" mean? I don't know, but maybe something like "Greater Addon Technology." We don't like making shit, so we made it greater...
I'm not sure how successful this will be yet. If people like it and constantly bug me about it then I might make some more for HAD Supercon.
If there's anything you think I should add, let me know.