And on it goes. I’ve finally integrated, albeit with gaffer’s tape, all of the components of the FaceMask on to the bike helmet. A screen covering the mouth, a small wired camera,a video Ipod, two wireless custom perf boards, and a lithium-polymer battery to power the whole thing are now held in place with gaff-tape and rubber bands.
As briefly explained in the video, the idea is to have two of these devices with one of the perf boards on the opposite helmet, and vise-versa. This way you can “slap” your mouth on to some one else’s face and they can do the same to you. The interaction is not limited to slamming your head against a hard object. It’s just what is in my thoughts at present.
This new perf board is fairly simple. I’ve built a standard 5 volt circuit for the atmega8 chip then regulated the voltage further to 3.3v for the Xbee. There’s a debugging LED on pin 13 of the atmel. The only other big thing on the board is a 3VDC DPDT relay. DPDT means double pole double throw. Basically I’m using the 6 pins as a manual video A/B switcher. The three blue terminal blocks other than the terminal block for the power, are wired to the relay. I’ve wired up two sets of two pins with signal and ground from two video sources – one from the video Ipod and one from the camera behind the screen which is pointing at the mouth. The other set of two pins is the signal and ground to the screen. I take the coil pin high to switch between contact with the two video signals.
I had a bunch of trouble after I got everything on the perf borad with the chip freaking out when the coil demagnetized, or magnetized to rapidly on and off. I thought perhaps there was some back voltage that was causing the problem so I threw a 3.3v Zener diode before and after the coil. No dice. Next I noticed my lack of any decoupling capacitors. I threw a 10uF cap before the 5v regulator, a 1uF cap after, and some on before and after the 3.3v regulator for good measure. This seems to have done the trick. I think the voltage was dropping when the relay was being fired.
The perf boards were a bitch to put together. In the course of prototyping the breadboards I also inadvertently fried three, count them three, Xbee’s simultaneously by putting an unregulated 9 volts through their cute little blue bodies. All dogs go to heaven. I’ve heard the same is true for honey bees. We can only hope this extends to Xbee’s. I’ll order $60 worth of new bee tomorrow.