What is it?

This third generation Desktop/Server ATX Power Supply Expansion Module and Soft Switch allows you to power your Raspberry Pi and add-on project boards using inexpensive desktop power supplies while keeping your Raspberry Pi cool with an off the shelf fan that you provide. The same great controller code found on previous generation boards aid in preventing the corruption of valuable disk files by enforcing controlled shutdowns of the Pi's operating system. Additionally, the Mini ATX PSU-Cool monitors the Raspberry Pi so that, in the case that the Pi is shut down by an application or from the command line, the desktop power supply will also turn off.

Specifications

• Uses inexpensive off the shelf ATX desktop supply. Works with 24 pin ATX connectors.
• Enables the operating system to perform controlled shutdown and reboots to minimize disk file corruption.
• You can program the Mini ATX PSU-Cool so that it will automatically reboot after a power failure if it was previously turned on.
• Back powers the Raspberry Pi with dedicated 5 VDC line.
• Compatible with common 40mm X 40mm fans with 4.2mm diameter mounting holes on 32mm centers.
• PCB is 1oz copper with ENIG finish.
• Uses high-quality Samtec and Molex connectors.
• Conforms to the Raspberry Pi Foundation's HAT footprint.
• 40 Pin GPIO stacking header allows the use of other HAT conforming boards.
• I2C signals brought out so you can plug in external modules such as a real-time clock
• Comes as a DIY kit to keep costs low. Assembly required

Operating Modes

• Program Mode: By default, the Mini ATX PSU-Cool is programmed to not auto-reboot after a power failure if it was already turned on. This is to maintain backwards compatibility with older model units. If you wish to have the Mini ATX PSU-Cool automatically reboot after power is restored, then please refer to the programming instructions in the manual.
• Power Off: On-board microcontroller, powered by the desktop 5Vsb line, waits for momentary power on button to be pressed.
• Power Up: LED pulsates slowly. Power is supplied to the Raspberry Pi and it boots up.
• Reboot: LED pulsates slowly. Raspberry Pi shuts down then reboots.
• Shutdown: LED pulsates slowly until boot up script has ended then pulsates quickly for 10 seconds before shutting off power to the Pi
• Hard Shutdown: LED dims entire time push button is depressed. Turns off power after 10 seconds.

Why did you make it?

• My projects often require multiple voltages in addition to the 3.3 VDC or 5 VDC supplies usually provided by the Raspberry Pi. Existing ATX type desktop power supplies provide the kind of power that I can use.
• The latest models of Raspberry Pi often require additional cooling. This board supports the installation of common 40mm X 40mm fans.
• Additionally, I needed my board to be a HAT conforming board so that I can build controller stacks using the other boards I designed as well as third-party boards. I am very particular in using stacked configurations because a stacked configuration is physically and electrically more robust.
• Finally, I wanted to mitigate the chance of file corruption by just turning off my Raspberry Pi without doing a controlled shutdown. This board allows me to do this.