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Raspberry Pi

The K8-Pi, K2-Pi-Servo and K2-Pi0 are hats for the Raspberry Pi. The Pi runs FPP, and the hat adds the power, outputs and connectors.

Which Raspberry Pis work

Board Raspberry Pi
K8-Pi, K2-Pi-Servo Pi 3 B+, Pi 4 or Pi 5. The hat's mounting holes match these Pis.
K2-Pi0 Pi Zero 2 W, the board it is designed for. It also works on an original Pi Zero W and on the bigger Pis, but see the warning on its board page.

Kulp Lights sells the boards with or without a Pi, and with or without an SD card with FPP on it.

Fitting the hat

The hat has a 40-pin socket on its underside that plugs onto the Pi's GPIO header.

  1. Disconnect all power.
  2. Screw M2.5 standoffs, nylon or metal, into the Pi's four mounting holes.
  3. Line the socket up with all 40 of the Pi's header pins, and press the hat down evenly until it is fully seated on the header and resting on the standoffs.
  4. Fix the hat to the standoffs with M2.5 screws.

Check before you power on

A hat that is shifted by a row or a column of pins can damage the Pi. Check that every pin is in the socket and none are left over. The standoffs keep the hat from bending down onto the Pi's USB and Ethernet ports; don't leave them out.

The hat sits close over the Pi, so a tall heatsink or fan on the Pi may not fit underneath it. Use a low-profile cooler.

Storage

FPP runs from a microSD card in the Pi. Use a good-quality card of 16–32 GB (A1/A2, U3), and the Raspberry Pi FPP image. See Getting the FPP software. Use FPP 10 or later; the current release is best.

Powering

The hat powers the Pi: its own regulator turns the supply on the power terminal into 5 V and feeds it to the Pi through the GPIO header.

Don't power the Pi a second way

  • Don't plug a supply into the Pi's own USB power socket while the hat is powered. The two supplies end up tied together. (The K8-Pi has a jumper that lets you power the Pi from its own supply instead; see its page.)
  • Don't connect the Pi's USB to a computer (USB tethering) while the hat is powered. Set the controller up over the network instead.

Using a 5 V supply

The hats' 5 V regulator can't quite hold 5 V when its input is only 5 V, so the Pi may report under-voltage. If you power one from a 5 V supply, turn the supply's output up to about 5.3 V (most LED supplies have an adjustment screw).

There is no power button on the hats. To turn off, use FPP's Shutdown, then switch off the supply.

Pixel outputs on a Pi

FPP drives the pixel ports through the Pi's display output, with its DPIPixels output:

  • Each string can have up to 1600 pixels. The frame rate is set by the longest string: about 40 fps at 800 pixels and 20 fps at 1600, and faster for shorter strings.
  • That variable frame rate arrived in FPP 10. FPP 9.5 runs only at 20 or 40 fps.
  • Smart receivers on the K8-Pi's differential ports work in v1 or v2 mode only.
  • The Pi's own audio output still works alongside the pixel outputs.

Network

The Pi 3 B+, Pi 4 and Pi 5 have built-in Ethernet and Wi-Fi. The Pi Zero 2 W has Wi-Fi only (2.4 GHz); set it up with FPP's Wi-Fi hotspot.