He tested the accuracy of Arduino’s Real-Time Clock (RTC) and compared it with millis(). The results are shocking - especially for the new R4 boards. Detailed testing and comparison between:
- Arduino Uno R4 WIFI
- Arduino Uno R4 MINIMA
- Arduino Diecimila
- Arduino Duemilanove
- Arduino Uno R2
- Arduino Uno R3
Deep dive into the Renesas R7FA4M1 chip’s documentation reveals why the R4’s RTC accuracy is problematic. Spoiler: It’s about HOCO, MOCO, and LOCO (yes, those are real names).