NOTE:What is it?
The K8-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 800 pixels (with power injection) at 40FPS. It also has 3 RJ45 differential ports that can output an additional 12 strings via differential receivers. Finally, there is an expansion header which can drive an additional 16 strings. The 800 pixels per string is the same for all strings. There is also a UART exposed via header pins which can drive a single DMX universe or Renard or LOR.
It also provides a Real Time Clock, an OLED display, and four push buttons for navigating menus on the display.
The “2.x” version has replaced the automotive “Mini Blade” fuses with eFuses. This allows the power to the ports to be completely turned off when no data is being output. They also provide current monitoring, trigger alerts, and more.
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. All 3 of the ports can be configured to drive a ws2811 pixel differential receiver board (available from pixelcontroller.com ). Both “Falcon Smart Receivers” and standard differential receivers are supported.
The 24pin expansion header also can drive additional pixels. There are 16 strings that are pulled out on the expansion header. This is compatible with the F16v4 expansion boards.
The PocketBeagle can be powered by the same power supply powering the pixels. Power supplies ranging from 5V to 18V are supported automatically with no need to adjust any jumpers.
Technical details: The ws2811 protocol is 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. 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 https://github.com/FalconChristmas/fpp/releases/
- 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.