Description: Brings soft on/off capability to the Raspberry Pi.
Features: Switches power to the Pi on with a momentary press of a button (not included). After the Pi is shut down, power to the device fully shuts off. Holding the power button for a few seconds will also fully shut power off. It’s made to work with any 5v power input and works on any version of the Raspberry Pi.
This works great with any Raspberry Pi project.
This board switches power on and off to your 5v device. It is designed with the Raspberry Pi in mind, but will work with almost any project that uses 5 Amps of power or less.
The connections labeled -IN and +IN are for the power input. This can come directly from a 5v power supply or from a battery pack. Both the front and back of the board are shown here for clarity.
The SWITCH connection goes to one side a momentary switch, and the other side of the momentary switch is connected to -IN.
The connections labeled -OUT and +OUT are for the power output. These lead to the device that’s being powered.
The GP1 pin connects to an available GPIO pin. It sends a signal to that pin when the power button is pressed.
The GP2 pin is used to keep everything powered on, and allows the board to automatically shut off power to your device after a shutdown process is complete. It needs to remain connected to a voltage above 3v (typically a GPIO pin). The board will power off your device around 3 seconds after voltage to this pin is disconnected.
This board acts as a soft switch, and switches the positive side of a power source on and off. Your device draws no power when the board is off.
Basic Function: When the momentary power button is pressed, the power is switched on. If the power button is then held for 3 seconds the power will be switched off. If this is all that is needed then the GP2 pin should be connected to the OUT+ pin. In this setup, the GP2 pin should not be connected to a GPIO pin.
Better Function: As with the basic function, when the power button is pressed the power is switched on. The difference with the advanced function though is the GP2 pin. This pin should be connected to a point on your device that generates a voltage above 3 volts. On the Raspberry Pi this will be any of the GPIO pins. The GPIO pin should be configured to switch to 3.3v when the Pi is powered on, and it switch off when the Pi is shut down. This means that 3 seconds after shutting the Pi down, this board will kill power to it completely until the power switched is pressed again. It also means that the Pi will automatically shut off if there is no SD card or OS installed. As with the basic function, the board will also turn off if the switch is held for 3 seconds.
Best Function: This board’s GP1 pin can be used to signal your device to issue a proper shutdown. This allows you to turn the Raspberry Pi (or similar device) without a keyboard or mouse. A pin on the Raspberry Pi can be configured to look for the button to be pressed, and then run the shutdown process once it detects the button. After the Pi is shut down, the GP1 pin feature will take over and kill power to the device entirely.
No software needed
You’ll need a modified config.txt file on your SD card. Simply add the following line of code to your config.txt:
This used GPIO 14, but you can modify it for any GPIO. Just change 14 to the GPIO number of the pin you choose.
The best method requires somewhat more software. It requires the same line to be added to config.txt, and also need a bit of software to run in the background. Download the file here and extract the zip.
Copy the extracted files to your SD card into the same root folder as the config.txt.
Insert the microSD card into the Pi and attach a USB keyboard. Power the system on and let it do its thing. You need to exit to the command line. If you’re using RetroPie, just press F4 on the keyboard. The following command has to be typed exactly as shown here. Don’t capitalize anything and don’t miss or add spaces.
Type the following command and press enter:
sudo bash /boot/setupoff.bash
Follow the prompts. Reboot the system when it asks you to.
It comes pre-configured to use GPIO4. If you want something different, then just modify othermodoff.py and change the 4 to the GPIO you prefer.
The gerber file is available on here:
Here is a jpg showing the component positions.
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10k Ohm 0805 SMD Resistor
100k Ohm 0805 SMD Resistor
300k Ohm 0805 SMD Resistor
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The resistors can be 1% or 5% tolerance, since this circuit does not require precision.
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