While your Pi is connected to a network it will be able to set it’s clock correctly using NTP. Without a network connection the system time and date will almost certainly be wrong. For some projects this is a problem especially if you are logging timestamps or performing other time sensitive operations.
This can be solved using a Real Time Clock (RTC) module. This will use a small coin cell battery to keep the time for the Pi even if it is turned off. When the Pi reboots it can set it’s own internal clock using the time held in by the RTC.
The easiest way of implementing an RTC is to buy a pre-made module. Luckily RTC modules are relatively cheap and easy to obtain. Some modules will attach directly the Pi’s GPIO header but these may get in the way of other devices so I prefer more generic modules that keep the GPIO clear for other purposes.
Each Friday is PiDay here at Adafruit! Be sure to check out our posts, tutorials and new Raspberry Pi related products. Adafruit has the largest and best selection of Raspberry Pi accessories and all the code & tutorials to get you up and running in no time!
Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, TinyGO, or even use the Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for CircuitPython, MakeCode, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.