What is it?
The F8-PB is a cape for the PocketBeagle designed to drive ws2811 LED pixels. It has 8 local ports (fused with LED indicators) that can each drive over 500 pixels (with power injection). 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 driver an additional 16 strings.
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-PB 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 PocketBeagle can be powered by the same power supply powering the pixels. There are jumpers on the board to select either 5V or 12V power.
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 USB network adapter – ethernet is preferred for initial setup, but WIFI (adapter must be supported by Linux/Beaglebone/Raspberry Pi) can also work if you use a micro-usb cable to connect to the PocketBeagle to do the WIFI setup.