Upcycle your ATX desktop power supply, reduce cord clutter and power your Raspberry Pi based projects all while aiding in preventing the corruption of valuable disk files through soft power shutdown with the Mini ATX PSU - Cool II for Pi. Additionally, the Mini ATX PSU - Cool II for Pi comes with a configurable watchdog timer and power management.

The Mini ATX PSU - Cool II has been totally re-designed from the popular Mini ATX PSU - Cool to take advantage of surface mount technology and a larger microcontroller to give you more features and, for those who like to do it yourself, greater ease of assembly with fewer parts.

Specifications:

• Features soft shutdown and reboot of your Raspberry Pi to minimize disk file corruption
• Works with most inexpensive off the shelf ATX desktop supplies using 20 or 24 pin ATX connectors
• On board DC - DC converter provides an ample 5.1 VDC at 3 amps to back power the Pi. Thus avoiding under voltage warnings
• Compatible with model 'A' and model 'B' of Raspberry Pi versions 3, 4
• Can be used with the Raspberry Pi 5 if you limit power usage to less than 3 amps. This is still enough power to support an external SSD for example
• The ATX 20/24 Pin Configuration Kit provides screw terminals to break out +12 VDC and +5 VDC for user projects. The screw terminals are rated for 3.0 amps
• The FDD/SATA Configuration makes it easier to create a small cluster environment while being powered by the same PSU as the the ATX 20/24 Pin Configuration
• Support for 4 wire 12 VDC PWM and 2 wire 12 VDC fans. Can speed adjust both fans together or independently
• Includes configurable watchdog timer to power cycle the Raspberry Pi in case the Raspberry Pi freezes up
• Includes configurable power management to automatically restart the Raspberry Pi after a power failure
• Breaks out the I2C pins from the Raspberry Pi. VCC is 3.3 VDC
• Mounts directly onto the GPIO header of the Raspberry Pi
• Board conforms to the standard Raspberry Pi Foundation's footprint.
• Choice of 40 pin GPIO 8.5 mm non-stacking or 11.65 mm stacking header. The stacking header allows use of other add-on boards or HATs.
• Comes as a DIY kit to keep costs low or fully assembled.

Operating Modes

• Turning on the ATX Power Supply: Turning on/plugging in the ATX power supply will supply a trickle voltage to the microcontroller on the Mini ATX PSU II - Cool. The Mini ATX PSU II - Cool will flash the power and Boot Ok LEDs in rapid succession to indicate the board is powered up and functioning.

• Power up the Raspberry Pi: Depressing the power switch when the Raspberry Pi is turned off will initiate the power-up sequence. The power indicator LED pulsates slowly until the Boot Ok command is received from the Raspberry Pi. When the Boot Ok command is received, the Boot Ok LED lights and the power LED goes steady on.

• Reboot: Depressing the power switch for greater than a half a second and less than three seconds while the Raspberry Pi is on will initiate a reboot of the Raspberry Pi. The power LED dims and the shutdown LED pulses once to signal the Raspberry Pi to reboot. When the Raspberry Pi starts to reboot, it sends a command to the Mini ATX PSU II - Cool to turn off the Boot Ok LED. The power LED will then pulsate until the Raspberry Pi has rebooted and the Mini ATX PSU II - Cool receives the Boot OK command. The power and Boot Ok LEDs will then go steady on.

• Shutdown: Depressing the power switch for over three seconds while the Raspberry Pi is on will initiate a shutdown of the Raspberry Pi. The power LED dims and the shutdown LED goes steady on to signal the Raspberry Pi to shut down. When the Raspberry Pi shuts down, it sends a command to the Mini ATX PSU II - Cool to turn off the Boot Ok LED. The Mini ATX PSU II - Cool will then wait a long enough period of time for the Raspberry Pi to perform a clean shutdown before turning off power to the Raspberry Pi.

• Hard Shutdown: In the event that the Raspberry Pi has frozen and is not responsive to commands from the Mini ATX PSU II - Cool or user interaction, you may force the Mini ATX PSU II - Cool to power off the Raspberry Pi. Depressing the power switch for greater than ten seconds will power off the Raspberry Pi.

• Command-line or Application Forced Shutdown: The Mini ATX PSU II - Cool has the ability to detect when a shutdown or reboot is initiated from the Raspberry Pi. When the user selects “Shutdown” or “Reboot” from the “Logout” menu, for example, the Raspberry Pi sends a command to the Mini ATX PSU II - Cool to turn off the Boot Ok LED and to wait a configurable amount of time. While it’s waiting, the power LED will pulsate. If the Raspberry Pi successfully reboots, it will command the Mini ATX PSU II - Cool to turn on the Boot Ok LED. If the Raspberry Pi does not reboot, for example the user initiated a shutdown, then the Mini ATX PSU II - Cool powers off the Raspberry Pi.

• Power Management: The power management option directs how the Mini ATX PSU II - Cool responds to power failure. In the event the power fails, the default mode of the Mini ATX PSU II - Cool is keep the Raspberry Pi powered off. Optionally, you can configure the Mini ATX PSU II - Cool to power on the Raspberry Pi after a power failure.

• Watchdog Timer: The Mini ATX PSU II - Cool has the option of power cycling the Raspberry Pi in the event the Raspberry Pi freezes for some reason and can no longer communicate with the Mini ATX PSU II - Cool.

• Reset Default Values You may, at any time, reset all edited parameters to their original values.

Why did you make it?

ATX desktop power supplies provide voltages and currents not available with your typical Raspberry Pi wall wart. People building retro arcades, model railroading layouts, etc... often find a need for 12 VDC and 5 VDC at higher currents in addition to being able to soft shutdown their Raspberry Pis. This board fulfils this need all while being easy to use and affordable.