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ClusterCTRL Stack

by 8086

The ClusterCTRL Stack (controller and passive backplane) is a simple way to both power and control cooling for a stack of 5 Raspberry Pi.


  • Powered by 12-24V PSU.
  • 20 pin header for Power (2x5V and 2xGND for each Pi).
  • 6 pin header for monitoring of Raspberry Pi (1 GPIO pin per Pi).
  • Onboard 10 Amp 5.1V DC-DC regulator (2 Amp allowance per Pi).
  • Connectors for 2 independently controlled fans.
  • Micro USB for ClusterCTRL allows controlling individual Pi power, fan, auto power on, voltages, etc.
  • USB Type-A connector 5V (ONLY) power output, can be used to power a 5V switch for example.

Passive backplane

  • Connects between the ClusterCTRL Stack Controller to each Raspberry Pi.
  • 20+6 pin connectors for ClusterCTRL Stack Controller.
  • 20 pin connector for each of the five regular sized Raspberry Pi (B+/2/3/3+/4).
  • Connects GPIO BCM18 of each Raspberry Pi to the Controllers monitor header.


As supplied the Controller can be used standalone - once power is applied to the ClusterCTRL Stack each Raspberry Pi will be powered on in 1 second intervals. The GPIO (BCM18) pin from each Raspberry Pi is monitored, when this is set high the corresponding FAN is turned on (P1/P2 = FAN1 and P3/P4/P5 = FAN2) as required to cool the Pi.

You can use any software on the Raspberry Pi nodes (Raspberry Pi OS/Ubuntu/etc.). To control the nodes you will need to install the clusterctrl software. Currently this needs to be manually installed - see the FAQ entry for manual installation steps.

To enable the fans to be turned on/off automatically when a Raspberry Pi requires cooling add the following to /boot/config.txt on each Raspberry Pi (in the example below it will turn the FAN on at 75C and off at 65C).


Connecting the ClusterCTRL Controller (via the Micro USB connector) you can use the "clusterctrl" tool which allows you to.

  • Control power for each Raspberry Pi individually.
  • Ganged FAN On/Off (when "off" the individual fans are still controlled via GPIO as above).
  • Measures both the voltage supplied to the Raspberry Pi and the 12-24V input voltage.
  • Configure power on state (each individual Pi can be set on/off by default).
  • A single Controller Pi can control many ClusterCTRL devices (Stack/Triple/Single/etc).

8086 recommend using two 70mm fans for cooling, one for the ClusterCTRL Stack Controller+P1+P2 (FAN1) and the other for P3/P4/P5 (FAN2).

What comes with the ClusterCTRL Stack

  • ClusterCTRL Stack Backplane.
  • ClusterCTRL Stack Controller.
  • 4x M2.5 12 mm F-F spacer.
  • 24x M2.5 25 mm M-F spacer.
  • 8x M2.5 6 mm screws.

What do I need to use the ClusterCTRL Stack?

  • 12-24 Volt Power Supply with 5.5 mm 2.1/2.5mm barrel jack (60 Watt recommended minimum).
  • 5x Raspberry Pi (Pi2/3/3+/4).
  • 2x 70 mm 5V fans (optional).
  • Controller Pi (can be one of the stack) (optional).
  • USB Cable to connect to controller (optional).
  • Ethernet Switch (optional).


STL files for the 3D printed case are available on Pinshape.