What is it?

The Pi EVSE hat allows a Raspberry Pi to perform all of the essential functions required for a complete electric vehicle charging station:

• +/- 12 V pilot generator
• A pilot feedback ADC to detect vehicle state changes
• A current transformer ADC to sense the current drawn from the vehicle
• A ground fault interruptor to interrupt power immediately if a ground fault is detected
• A ground continuity monitor / relay test system to insure that when the power is on that the ground impedance is low, and when the power is off the output power contacts have no voltage on them.
• A voltage sense ADC to detect the voltage of the incoming power.

The system consists of two boards - the Pi hat itself, plus an HV board. The HV board supplies power to the Raspberry Pi (as well as the Pi Hat), so there's no need for any other power supply. The HV board also can drive either a 12 volt DC external relay or a 208/240 VAC contactor.

Note that in the pictures above, the Raspberry Pi is not included. You get the Pi Hat, a 10 pin FFC, and the HV board. Also, at present no software is available. Please see the Hackaday.io project linked here for documentation.

What makes it special?

The Raspberry Pi is a powerful computer with sophisticated GPIO subsystems that makes the job of software control of an EVSE a relatively easy task. In addition, it's powerful networking abilities allow a nearly infinite level of remote monitoring and control, customizable for any purpose you can imagine. The Pi Hat system means that making your own Linux based EVSE is a purely software project.