4 Channel Solid State Relay HAT


Optional Extras
Handled Jumper Link

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The CTRL HAT is a Raspberry Pi I/O automation board for use with solid state power relays (SSRs). Designed for switching high power loads without the need for costly extra hardware such as SSR modules or contactors.

CTRL HAT is ideally suited to automation or industrial control applications requiring high-speed switching, or switching of loads not suitable for regular mechanical relays, such as motors, power supplies, or noise sensitive equipment such as amplifiers.

Featuring the well-documented MCP23017 16 channel GPIO expander, the CTRL HAT is easy to setup and control via I2C. It can be used with any device featuring an I2C bus and works with 3.3V or 5V devices (eg, Arduino); by selecting the appropriate jumper (see device compatibility). Channels 0-3 (group A) are utilised for the relays, giving you an extra 12 GPIOs for use with your project.

The CTRL HAT is powered through the host Raspberry Pi using the GPIO port and can be used in-conjunction with other expansion boards (check-out our HAT RACK mounting board). Up to eight CTRL HATs can be used with a single Raspberry Pi. The relays can be powered separately by removing the jumper marked “Link”, so you can use an external supply to power the relays, reducing the load on the Raspberry Pi. Use of an external power supply is recommended if you plan to connect multiple HATs to your Raspberry Pi.


  • Support 4 industry standard SIP type solid state relays
  • Up to 10A @ 250V / 16A @ 250V (forced air cooled)
  • Huge range of compatible solid state relays (known list)
  • Active relay status LED indictors
  • Easy to use interactive web GUI
  • Based on the MCP23017 16-port GPIO expander
  • Jumper selectable I2C address & GPIO voltage (3.3V / 5V)
  • Can be used with 3.3V or 5V I2C host devices (eg, Arduino)
  • Built-in user programmable ID EEPROM
  • Conforms to Raspberry Pi HAT Specifications

What’s Included

  • 1x CTRL HAT
  • 2x Jumper Links

Interactive Web GUI

Once installed on your Raspberry Pi, this interactive GUI allows quick & easy control of your CTRL HAT without the need for any coding. It is designed to be both a user guide & quick reference to the CTRL HAT pinout. The GUI is fully responsive and adapts to any screen size.

Check-out the Live Demo.

Device Compatibility

The CTRL HAT is fully compatible with all 40-way Raspberry Pi models and clones.

Device ModelCompatibility
Raspberry Pi 1 Model A+/B/B+✔️
Raspberry Pi 2 Model B✔️
Raspberry Pi 3 Model B/B+✔️
Raspberry Pi 4✔️
Raspberry Pi 5✔️
Raspberry Pi Zero✔️
Raspberry Pi Zero 2✔️
Asus Tinker Board✔️
Banana Pi✔️
Orange Pi✔️

To use with Arduino or any other 5V device the 3V3 jumper must be moved to 5V.
Use the SDA & SDL breakout pins for I2C communication.

Compatible Relays

Check-out our list of known compatible solid state relays on GitHub.

I2C Address Selection


Schematic Diagram


Maximum PCB Ratings

  • 10A @ 250V (ambient temperature)
  • 16A @ 250V (forced air cooling required)

Exceeding these limits may overload the PCB.


  • UL 796 certified manufacturer
  • RoHS compliant (lead free)
  • CE compliant (certificate)


You can find this and our other Raspberry Pi projects on our GitHub page.

Gerber Files

Available for download here.

In The Wild

Additional information

Weight18 g
Dimensions56 × 65 × 19 mm


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