What is it?
The F8-B is a cape for the BeagleBone Black designed to drive ws2811 LED pixels. It has 8 local ports (fused with LED indicators) that can each drive over 700 pixels (with power injection) at 40FPS. It also has 3 RJ45 differential ports that can output an additional 12 strings or 8 universes of DMX. Finally, there is an expansion header which can drive an additional 16 strings. The 700 pixels per string is the same for all strings.
The new “v3” version also provides a Real Time Clock, temperature sensors, a header for an OLED display, and two push buttons for navigating menus on the display.
Why did you make it?
Animated Christmas Light displays typically use ws2811 Pixels for things like house outlines, candy canes, tree’s, etc… The F8-B was designed to drive a large number of pixels, yet remain relatively small so it can be easily hidden or mounted onto the prop.
What makes it special?
The 8 local ports provides enough outputs to handle most situations where a small controller is desirable. It’s significantly more than the 2 ports of the various Raspberry Pi controllers, but not as large as the standard 16 port controllers that are typically used for pixel dense locations.
However, the 3 RJ45 ports provide additional output capabilities to allow for future expansions. 2 of the ports can be configured to either drive a ws2811 pixel differential receiver board (available from pixelcontroller.com ) OR be configured to output 4 universes of DMX for each port. The third RJ45 can only drive ws2811 pixels via a receiver board.
The 40pin expansion header also can drive additional pixels. There are 16 strings that are pulled out on the expansion header.
The BeagleBone can be powered by the same power supply powering the pixels. There are jumpers on the board to select either 5V or 12V power. Alternatively, the BeagleBone can be powered by it’s own barrel connector if an on-board jumper is removed.
Technical details: Both the DMX and ws2811 protocols are extremely timing dependent and are generally not drivable via a general purpose Linux CPU. The FPP software uses the two semi real-time PRU’s available on the PocketBeagle to handle the protocol specific timings. One PRU is used for the ws2811 protocol strings and the other PRU is used for the DMX timings. Using the PRU’s also allows the main CPU to be free for other things such as network IO.
You WILL need:
- ws2811 pixels
- A good quality SD card with the latest FPP image installed on it. The latest FPP image can always be found at http://dankulp.com/bbb/
- A BeagleBone Black, BeagleBone Black Wireless, BeagleBone Green, or SanCloud BeagleBone enhanced.
Note: a BeagleBone Green Wireless will NOT work.