How To Hot-swap Power In Your Raspberry Pi Without Stopping Work!Friday, March 18, 2016
MoPi is a little anon circuit board that plugs on top of the Raspberry Pi board and allows you to plug in all sorts of power supplies such as a standard rechargeable AA battery pack, solar panels or a chunky power brick supply. You can even plug two different power supplies at once. You can hot swap power supplies without stopping work. If you are in the car you can plug in your Raspberry Pi via the standard cigarette lighter plug.
MoPi consists of a 5-volt switching mode regulator and microcontroller ADC (Analogue to Digital Converter) which shuts down the Raspberry Pi cleanly when batteries discharge. MoPi also gives a set of warning level states (power off, battery empty, battery level critical, battery level low, battery level good) before it shuts down to give you a chance to swap in another power supply. The MoPi microcontroller supplies these states via three Raspberry Pi GPIO pins (and also sets on-board indicator LEDs accordingly).
When working with the Raspberry Pi, it's always handy to know when the battery is full, when it is starting to get low and when it is critical. The fact that the MoPi is able to give you those signals both when logged in to the Pi and visually from the battery pack itself it's really a useful feature to have on board!
MoPi solves the problem of mobile power for the Pi by being able to regulate to supply the constant 5 volts at up to around 1 amp that the Raspberry Pi requires, as well as taking care of all the functions related to voltage level monitoring, level signalling (via the LEDs and the GPIO interface), and on/off switching of the +5V supply to the Pi.
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