CarPiHAT – Car Interface HAT for Raspberry Pi

The TJD CarPiHAT is designed to make interfacing your Raspberry Pi to your car, boat, truck, or any other 12V-based system much easier.

Whilst shopping for a simple power supply and shutdown solution for his OpenAuto Pro installation, the designer (Sam Taylor-Jones) was unable to find a solution that offered all of the features he was after in a single HAT. Unhappy with the concept of stacking multiple hats to achieve the result he was after, Sam decided to design his own, and thus, the CarPiHAT was born!

The HAT includes a 12V to 5V buck converter to power your Raspberry Pi and touchscreen, safe shutdown circuitry, a low (< 1mA) current draw when switched off, dedicated reverse/illumination/aux 12V inputs, 2x general-purpose opto-isolated 12V inputs (5 in total), 2x high current high side switched 12V outputs (@1A) ideal for switching relays/lights, an independent CAN bus port, RTC, I2C bus, 1W for temperature sensors etc and 5V out for displays and other components.

The HAT conforms to the official Raspberry Pi specification and is compatible with any Raspberry Pi with the 40 pin GPIO header, although it is primarily designed for use with non-zero variants.

The HAT comes with a 6-way Molex NanoFit pigtail, standoffs and screws. It’s available with or without a shroud+cooling fan (please select option before adding to basket). We also stock  Molex NanoFit 4-way pigtails compatible with the board’s connectors, for making easy terminations to existing wiring (useful for connections such as I2C, CAN etc).

Need more IO? Check out the CarPiHAT IO Expander!

We also stock a PRO 5 version of the CarPiHAT which has a high-quality DAC onboard, re-worked with higher quality inductors and a new power switching IC, with improved power conversion and filtering that provides up to 5A that Raspberry Pi 5 (sometimes) requires.

Features

• 12V -> 5V buck converter to power the Pi and touchscreen, with fuse and filtering.
• Safe shutdown circuitry to allow the pi to control its own power.
• < 1mA current draw when switched off.
• Dedicated reverse, illumination and aux 12V inputs.
• 2 general purpose 12V inputs. (for a total of 5 12V inputs)
• 2 high current, high side switched 12V outputs (@1A). (great for switching relays, lights ect)
• 1 independent CAN bus port.
• Real-time clock to maintain system time across reboots.
• Broken out I2C bus
• Broken out 1W for temperature sensors etc
• 5V Power Output for displays and other 5V devices
• Optional: protective shroud

All 12V inputs are opto-isolated to ensure the Raspberry Pi is well protected against the typically noisy automotive power environment.

A note on Touch Display 2 compatibility

The Raspberry Pi Touch Display 2 has a new block connector rather than the previously used jumper wires. This makes wiring a little awkward!

To power the display, you can either snip the connector and solder directly to the CarPiHAT’s 5V/GND pads (or solder a pin header to those pads and create a jumper solution), or use this handy USB Power Breakout from Eplop.

Who might use a CarPiHAT?

At a basic level, anyone who is looking to install a Raspberry Pi in their car, or another 12V system.

Since the HAT allows the Raspberry Pi to take control of its own power supply, this means corrupted SD cards (due to unexpected power loss) are a thing of the past! A simple script, or service, running on the Pi allows you to monitor a 12V feed, and gracefully shut down when this is removed.

At a more advanced level, the additional peripherals on the HAT would allow you to connect any number of inputs or outputs to the system. The 12V outputs allow you to control lights, amplifiers, relays, solenoids, you name it! The CAN port allows the connection of an IDrive controller for a great human interface experience, or even interrogate your car’s ECU with some custom software. The I2C and 1W ports allow you to connect any number of external devices such as light, temperature or environmental sensors, or even external microcontrollers!

There’s a project log and inspiration page here including a link to the designer’s very own project build.

How to use the CarPiHAT?

The designer has set up a GitHub page with full information (see sidebar), including a Quick Start Guide to get you started.

The BlueWave Studio forum is also a useful resource.

Pinout

Package Contents

• 1x CarPiHAT Board
• 1x 6-way Molex NanoFit Pigtail
• 4x Metal Standoffs
• 4x Metal Screws
• OPTIONAL (select before adding to cart): Protective Shroud + Cooling Fan