--- title: "Real-time clocks: Does anybody really know what time it is?" url: https://daily.dev/posts/real-time-clocks-does-anybody-really-know-what-time-it-is--mnlqaptlr source_url: https://www.embeddedrelated.com/showarticle/90.php type: article source: "EmbeddedRelated" published: 2026-05-31T07:48:18.682Z updated: 2026-05-31T09:18:53.596Z tags: ["embedded"] reading_time: 14 upvotes: 0 comments: 0 language: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Real-time clocks: Does anybody really know what time it is? **[EmbeddedRelated](https://daily.dev/sources/embeddedrelated)** · 14 min read · 0 upvotes · 0 comments ## Summary A practical critique of real-time clock (RTC) chips from an embedded systems perspective. Most RTC chips store time as calendar structures (year/month/day/hour/minute/second) rather than as a Unix epoch offset, forcing engineers to write complex conversion code for interval arithmetic. The post explains the tradeoffs between structured and offset time encodings, details the challenges of atomically reading multi-field RTC registers without race conditions ('The Dance'), discusses subsecond resolution limitations, and covers UTC vs. local time pitfalls including DST and leap seconds. The author's wishlist for an ideal RTC chip includes: epoch-offset encoding, a 15-bit subseconds field, an explicit snapshot/capture register, and offset-encoded alarms. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Clock Synchronization Is a Nightmare](https://daily.dev/posts/clock-synchronization-is-a-nightmare-uxf2ft5vt) · Hacker News · 2 upvotes · 0 comments - [Time in C\+\+: Additional clocks in C\+\+20](https://daily.dev/posts/time-in-c-additional-clocks-in-c-20-tvjsm1ztd) · Sandor Dargo · 4 upvotes · 1 comments --- Tags: [#embedded](https://daily.dev/tags/embedded) [View this post on daily.dev](https://daily.dev/posts/real-time-clocks-does-anybody-really-know-what-time-it-is--mnlqaptlr)