The s_shut project describes a very simple system in order to shut down Raspberry Pi safely. It consists of a Python 3.x script s_shut.py, a simple schematic and this description.
This project is tested in Raspberry models 3, 3B, 4B, zero-wh under raspbian V10 and above.
The python script uses the awesome libgpio library
A running Linux computer should not be powered off without a controlled shutdown by the operating system, because this can result in damaging the file system on the SD_Card. Controlled power down is especially critical to achieve in so called headless systems with no monitor and keyboard. Raspberry computers do not provide a reset or power down switch. The presented solution allows initiating shutdown or a restart with a switch or an external signal. It also provides a hardware signal (e.g. LED) indicating the running operating system state.
Power up
After Linux boot, a selectable port (default BCM21) is driven high and LED goes ON
Switch pressed > 2 seconds
Linux command 'shutdown -P now' will be executed by the script s_shut.py .
As soon as critical storage operations are completed, LED goes OFF.
Switch double clicked
System shuts down and restarts.
Linux command 'shutdown -r now' will be executed by the script s_shut.py.
Switch pressed > 6 seconds [optional]
System shuts down and activates a selectable port until no more SD card access occur. This signal may be used in order to completely power down Raspberry by switching off the external power supply .
Restart after shut down
This is only achievable by external power off and on again.
(A much more convenient solution is using the "UPS-2" project, that will follow here in the first Quarter 2021)
Project Components
- The python script s_shut.py
- A push button switch
- A high efficiency LED
- 1 or 2 resistors
See user-guide.md
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