Onboard DS1307 chipCR1220 button battery never offCan be directly operated by shell scriptLead out the serial port of for debuggingProgrammable square wave outputProduct interface:For B version 2X13 socketFor A+/B+/Gen 2 2X20 socketSupport Raspberry 3B+/3B/A+/B+/22*5p 2.54mm pitch interface.Product parameters:Working voltage is 5VClock accuracy of 2ppm from 0C to +40CThe real-time clock provides seconds, minutes, hours, day of the week, date, month, year information, and provides leap year compensation valid until 2100Two calendar alarm clocksType: expansion boardWorking voltage: 5VOperating temperature: -10C to +85CApplicable models: 4B/3B+/3Bcolor:RedMaterial:PCBPackage Contents:1 x Expansion BoardOnly the above package content, other products are not included.Note: Light reflection and different displays may the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.