I finally got around to assembling a stand alone version of the RBox. As some of you correctly noted building a videogame for the price of a latte that depends on a $30 dev kit is cheating a bit. This version is self contained and while not practical or useful it is at least fun to build.
The design sandwiches a lithium button cell between the psp joystick and the pcb. It adds a single button that serves as both the power switch and a fire button. 2 axis control + fire may seem a modest level of input but modern standards but if it was good enough for Atari is is good enough for me.
Thin bendy metal on top of the cpu and on the bottom of the joystick provide a suprisingly effective friction fit for the CR1632 battery. Don’t try to solder directly to the metal on the bottom of the joystick. When running a game and playing audio the device uses about 28ma so I get about 4 hours of continuous use from the CR1632. Feel free to use a CR1616 or CR1620 for a slimmer look and more frequent battery replacement.
The schematic is virtually identical to the prototype with a few exceptions. The joystick VCC line is connected to a GPIO rather than VCC to reduce power during normal operation and especially during deep power down. The fire button is connected to the WAKEUP pin that brings the beast back from deep power down. The code will deep power down the RBox after 3 minutes of inactivity. While turned off the RBox uses about ~200na as far as I can measure on my crappy meter. The board supports both composite and s-video.
If you don’t feel like making your own pcb order them from http://dorkbotpdx.org/wiki/pcb_order. This is simply the cheapest and best way of getting pcbs in small volume. Nobody else comes close. Unless you really like what ferric chloride does for your sneakers there is no reason not to use these guys.
New code, schematic and pcb posted on https://sourceforge.net/projects/rbox/. If you would like a kit post a comment and if there is lots of interest I will see if I can get one organized.
Until next time