Circuits: What is your best way to make a "hard drive", or a part of the system that saves state after power is off?

2    15 Sep 2017 14:44 by u/Omnipresent

Ive been thinking about playing with motors, electromagnets, and so forth but I still think there might be a more compact way of saving information after the system loses power.

Any ideas or insight?

4 comments

4 u/xyzzy 15 Sep 2017 14:58

EEPROM?

Also this is probably the wrong sub for this question, try /v/electronics if there are still readers.

2 u/tame 15 Sep 2017 15:18

What are you trying to accomplish? How much data? Basically anything up to a few kilobytes, EEPROM or some other kind of non-volatile RAM is the way to go. More than that, just spend the extra dollar or whatever and add a micro-SD reader, and you can store up to I think 256GB on something the size of your pinky nail.

1 u/skruf 16 Sep 2017 01:03

As already stated, EEPROM is your go-to here, however these have a somewhat low write limit; after the limit the chip cannot be written to. The other option is to interface an SD card, which is somewhat easily done with any MCU and using a simple implementation of the FAT file system.

1 u/roznak 16 Sep 2017 01:43

SD card would be best but you better save data BEFORE there is a risk of losing data. Your design must take that into account. One way could be having a second controller that has the only purpose to store data after the main controller loses power. That one can be battery backed up.