Volatile RAM. Thinking DS1307 without battery.

Author	Message
CaptainBoing Guru Joined: 07/09/2016 Location: United Kingdom Posts: 2122	Posted: 09:18pm 21 Jan 2025         twofingers said   The DS3231 RTC chip has 7 bytes that are actually intended for alarms. These could be used to remember states beyond power off. this is a great tip! one caveat, the registers store BCD and are not fully 8 bits (bit 7 of each register means something) so you need to be attentive that any values written conform. I have just tried here writing &h7F, and it got munged into some weird value I have yet to interpret. Mine come from 99p modules off ebay so are probably chinese knock-offs so ymmv. Stick to a few flags in the bottom couple of bits and you should be fine. Edited 2025-01-22 07:23 by CaptainBoing