South Berkeley Electronics recently released their new HAT — the PiDog2, designed to provide a hardware watchdog and power management options to any 40-pin GPIO Raspberry Pi (except the Model A). Sometimes Raspberry Pi’s crash, whether it’s a coding error, heat or application related, and while the board is capable of resetting itself, it can’t turn itself off or on. What’s more, any peripherals connected to the Pi will continue to draw power even if you shut down the OS.
Potential crashes and power issues limit the Pi from being deployed remotely, as they need to be physically rebooted. The PiDog2 HAT solves those issues, as it can shut the power off to the Pi after a certain period has passed, and can perform a complete power-down after a clean shutdown. It can also power the Pi back up after a specified time, and even provide the Pi with measurements of 3.3V and 5V power supplies.
As far as hardware does, the PiDog2 is outfitted with an ATtiny84 microcontroller, P-FET power switch, micro USB port, JST connectors (12V battery monitoring), 40-pin Pi header for connecting to the Pi and debug headers. It also sports a 4-pin header with 2X grounds (5V switched/unswitched), 2x3 ICSP connection (for programming AVR), a pair of status LEDs, and reset button.
According to South Berkeley Electronics, the PiDog2 functions by inserting a MOSFET between the 5V USB connector and the Raspberry Pi, enabling it to turn itself off and on. The board is programmed to appear as 32-bit registers with various countdown timers and control bits, and SBE offers a Python library (on GitHub) that allows you to interact with those registers for adjusting those parameters.
The PiDog2 is now available on South Berkeley Electronics’ Tindie page for $20, but be forewarned; it does require some soldering before it can be used with the Raspberry Pi.