{"product_id":"m5stack-rtc-unit-hym8563-i2c-clock-u126","title":"M5Stack RTC Unit – HYM8563 I2C Real-Time Clock | U126","description":"\u003cp\u003e\u003cvideo controls muted playsinline style=\"width:100%;height:auto;border-radius:8px;\"\u003e\u003csource src=\"https:\/\/m5stack.oss-cn-shenzhen.aliyuncs.com\/video\/Product_example_video\/Unit\/UNIT_RTC_VIDEO.mp4\" type=\"video\/mp4\"\u003e\u003c\/video\u003e\u003c\/p\u003e\u003cp\u003eThe M5Stack RTC Unit provides battery-backed date and timekeeping for offline data loggers, scheduled controllers, clocks, access terminals, and embedded devices that must retain time while the main host is powered down. Its HYM8563 real-time clock communicates over I2C at address 0x51 and stores seconds, minutes, hours, weekday, date, month, and year. Firmware can read the clock at startup, synchronize it from a trusted network source, and continue timestamping local events when network access is unavailable.\u003c\/p\u003e\u003ch2\u003eBattery-Backed Timekeeping with the M5Stack RTC Unit\u003c\/h2\u003e\u003ch3\u003eMaintain Date and Time During Host Power Loss\u003c\/h3\u003e\u003cp\u003eThe backup supply allows the HYM8563 to continue counting when the main controller is switched off, so the host can recover a usable calendar time after restart.\u003c\/p\u003e\u003ch3\u003eRead Calendar Data over I2C Address 0x51\u003c\/h3\u003e\u003cp\u003eThe host can read seconds, minutes, hours, weekday, date, month, and year through the Grove I2C connection. The documented I2C address is 0x51.\u003c\/p\u003e\u003ch3\u003eSynchronize Offline Logs with Network Time\u003c\/h3\u003e\u003cp\u003eA connected device can periodically correct the RTC from NTP, GNSS, or another trusted source, then use the local clock to timestamp measurements during network outages.\u003c\/p\u003e\u003ch2\u003eM5Stack RTC Unit Applications\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eOffline sensor and event data logging\u003c\/li\u003e\n\u003cli\u003eScheduled control and timed automation\u003c\/li\u003e\n\u003cli\u003eClocks, calendars, and information displays\u003c\/li\u003e\n\u003cli\u003eAccess, attendance, and check-in terminals\u003c\/li\u003e\n\u003cli\u003eNetwork-independent timestamp retention\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eHow to Integrate the M5Stack RTC Unit\u003c\/h2\u003e\u003col\u003e\n\u003cli\u003eConnect the unit to a compatible Grove I2C port and confirm that address 0x51 is free.\u003c\/li\u003e\n\u003cli\u003eAt first setup, write a trusted date and time to the RTC.\u003c\/li\u003e\n\u003cli\u003eOn every startup, read the clock and validate the year and status before using timestamps.\u003c\/li\u003e\n\u003cli\u003eStore timestamps in a defined time zone or UTC and handle daylight-saving rules in application software.\u003c\/li\u003e\n\u003cli\u003ePeriodically compare the RTC with a trusted reference and correct accumulated drift when necessary.\u003c\/li\u003e\n\u003c\/ol\u003e\u003ch2\u003eM5Stack RTC Unit Deployment Notes\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eA real-time clock reduces dependence on network time but still accumulates oscillator drift.\u003c\/li\u003e\n\u003cli\u003eValidate clock data after long storage, battery replacement, or an invalid-status indication.\u003c\/li\u003e\n\u003cli\u003eThe RTC stores calendar values; time-zone and daylight-saving conversion belong in host software.\u003c\/li\u003e\n\u003cli\u003eKeep the backup battery and unit away from excessive heat, moisture, and mechanical damage.\u003c\/li\u003e\n\u003cli\u003eThis module is not a precision timing reference for billing, legal metrology, or safety-critical synchronization.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eM5Stack RTC Unit Development Resources\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003e\u003ca href=\"https:\/\/docs.m5stack.com\/en\/products\/sku\/U126\" target=\"_blank\" rel=\"nofollow noopener noreferrer\"\u003eM5Stack RTC Unit Official Documentation\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"https:\/\/uiflow2.m5stack.com\/\" target=\"_blank\" rel=\"nofollow noopener noreferrer\"\u003eUiFlow2 Development Environment\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"https:\/\/docs.arduino.cc\/software\/ide\/\" target=\"_blank\" rel=\"nofollow noopener noreferrer\"\u003eArduino IDE\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"LogicBoundless","offers":[{"title":"Default Title","offer_id":49240388075735,"sku":"LB-M5-U126","price":6.9,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0801\/8952\/2135\/files\/1_effe80c2-6c97-4d55-a45e-e97821d74e2e.jpg?v=1783243291","url":"https:\/\/logicboundless.com\/products\/m5stack-rtc-unit-hym8563-i2c-clock-u126","provider":"LogicBoundless","version":"1.0","type":"link"}