Raspberry PI Power Switch
July 3rd, 2015
Lately, we have been working on a few projects that make use of the most excellent Raspberry PI which, if you've never heard of it, is a credit card sized computer that was designed by the Raspberry Pi Foundation in order to advance computer education for adults and children. The PI can be bought for less than £30 and has a nice range of general purpose I/O built into it for controlling pretty much anything you want.
What it does not have however is a power switch! We decided to build one of our own. This is what we wanted it to do :
- Be able to switch the PI on without any initial power supply active.
- Know when our main application on the PI was up and running, and switch on an auxiliary power supply for the externally connected hardware.
- When the user wants to shut down the system, switch off the auxiliary power supply, then safely shut down the PI and the main supply.
- Provide visual indication to the user about what state the system is in.