HAT or pHAT for Raspberry Pi. Designed with the Pi Zero W in mind, so it shares the footprint of the Zero.
HAT has an ATmega328PB connected via I2C, SPI and UART,allowing both flashing, and many forms of communication.
Included a space for a Mini DC-DC voltage regulator. These are good for 3A of power, but make sure to solder the 5V pads and cut the ADJ pad lead.
Headers for SPI(ICSP) and both...